U.S. patent application number 16/444430 was filed with the patent office on 2019-10-03 for photoelectric conversion element, solar cell and composition.
This patent application is currently assigned to FUJIFILM Corporation. The applicant listed for this patent is FUJIFILM Corporation. Invention is credited to Toshihiro Ise, Katsumi Kobayashi, Hirotaka Satou, Kenji Shirokane.
Application Number | 20190304707 16/444430 |
Document ID | / |
Family ID | 56880122 |
Filed Date | 2019-10-03 |
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United States Patent
Application |
20190304707 |
Kind Code |
A1 |
Satou; Hirotaka ; et
al. |
October 3, 2019 |
PHOTOELECTRIC CONVERSION ELEMENT, SOLAR CELL AND COMPOSITION
Abstract
Provided are a photoelectric conversion element including a
first electrode having a photosensitive layer including a light
absorber on a conductive support and a second electrode facing the
first electrode, in which the light absorber includes a compound
having a perovskite-type crystal structure including organic
cations, cations of a metallic atom other than elements belonging
to Group I of the periodic table, and anions, and at least some of
the organic cations constituting the compound are organic cations
having a silyl group and a solar cell using the photoelectric
conversion element. Also provided is a composition containing a
compound represented by Formula (1a) and a halogenated metal:
R.sup.1.sub.3Si-L-NR.sup.2.sub.3Hal Formula (1a) in the formula,
R.sup.1, R.sup.2, and L are specific groups; and Hal represents a
halogen atom.
Inventors: |
Satou; Hirotaka;
(Ashigarakami-gun, JP) ; Shirokane; Kenji;
(Ashigarakami-gun, JP) ; Ise; Toshihiro;
(Ashigarakami-gun, JP) ; Kobayashi; Katsumi;
(Ashigarakami-gun, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FUJIFILM Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
FUJIFILM Corporation
Tokyo
JP
|
Family ID: |
56880122 |
Appl. No.: |
16/444430 |
Filed: |
June 18, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15658995 |
Jul 25, 2017 |
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16444430 |
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PCT/JP2016/055520 |
Feb 24, 2016 |
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15658995 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y02P 70/50 20151101;
Y02E 10/549 20130101; H01L 51/0047 20130101; H01G 9/2059 20130101;
Y02P 70/521 20151101; H01L 51/0094 20130101; H01G 9/2027 20130101;
H01L 51/422 20130101; Y02E 10/542 20130101 |
International
Class: |
H01G 9/20 20060101
H01G009/20; H01L 51/00 20060101 H01L051/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 6, 2015 |
JP |
2015-045167 |
Jan 22, 2016 |
JP |
2016-010695 |
Claims
1. A composition comprising: a compound represented by Formula
(1a); and a halogenated metal, R.sup.1.sub.3Si-L-NR.sup.2.sub.3Hal
Formula (1a) in the formula, R.sup.1 represents a hydrogen atom, an
alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl
group, an alkoxy group, an aryl group, a heteroaryl group, or an
aliphatic heterocyclic group, R.sup.2 represents a hydrogen atom,
an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl
group, an aryl group, a heteroaryl group, or an aliphatic
heterocyclic group, L represents a divalent linking group, and Hal
represents a halogen atom.
2. A photoelectric conversion element comprising: a first electrode
having a photosensitive layer including a light absorber on a
conductive support; and a second electrode facing the first
electrode, wherein the photosensitive layer is formed from the
composition according to claim 1.
3. The composition according to claim 1, wherein R.sup.1 is an
alkyl group, an aryl group, or a heteroaryl group.
4. The composition according to claim 1, wherein L is a divalent
linking group selected from an alkylene group, a cycloalkylene
group, an alkenylene group, an alkynylene group, an arylene group,
a heteroarylene group, --O--, --S--, and --NR.sup.L-- or a divalent
linking group formed by combining two or more linking groups, and
R.sup.1 represents a hydrogen atom or an alkyl group.
5. The composition according to claim 4, wherein L is an alkylene
group, an arylene group, or a divalent linking group formed of a
combination of an alkylene group and an arylene group.
6. The composition according to claim 1, wherein the compound
represented by Formula (1a) has an alkylene group in L, and L and
NR.sup.2.sub.3 are linked to each other through the alkylene group.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Divisional Application of U.S.
application Ser. No. 15/658,995 filed on Jul. 25, 2017, which is a
Continuation of PCT International Application No. PCT/JP2016/055520
filed on Feb. 24, 2016, which claims priority under 35 U.S.C.
.sctn. 119 (a) to Japanese Patent Application No. 2015-045167 filed
on Mar. 6, 2015, and to Japanese Patent Application No. 2016-010695
filed on Jan. 22, 2016. Each of the above applications is hereby
expressly incorporated by reference, in its entirety, into the
present application.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The present invention relates to a photoelectric conversion
element, a solar cell, and a composition.
2. Description of the Related Art
[0003] Photoelectric conversion elements are used in a variety of
optical sensors, copiers, solar cells, and the like. It is
anticipated that solar cells will be actively put into practical
use as cells using non-exhaustible solar energy. Among them, active
research and development is underway regarding dye sensitized solar
cells in which an organic dye, a Ru bipyridyl complex, or the like
is used as a sensitizer, and the photoelectric conversion
efficiency thereof reaches approximately 11%.
[0004] Meanwhile, in recent years, research results that solar
cells in which a metallic halide is used as a compound having a
perovskite-type crystal structure are capable of achieving a
relatively high photoelectric conversion efficiency have been
reported and attracted attention (for example, Science, 2012, vol.
338, pp. 643 to 647).
SUMMARY OF THE INVENTION
[0005] Photoelectric conversion elements or solar cells in which a
compound having a perovskite-type crystal structure (hereinafter,
also referred to as "perovskite compound") is used have attained
certain achievements in terms of the improvement of photoelectric
conversion efficiencies. However, photoelectric conversion elements
or solar cells in which a perovskite compound is used have recently
attracted attention, and cell performance other than photoelectric
conversion efficiencies are barely known.
[0006] For photoelectric conversion elements and solar cells, there
is a demand not only for a high photoelectric conversion efficiency
but also for durability sufficient to maintain initial performance
in on-site environments in which the photoelectric conversion
elements and solar cells are actually used.
[0007] However, it is known that perovskite compounds are likely to
be damaged in highly humid environments. In actual cases, the
photoelectric conversion efficiencies of photoelectric conversion
elements or solar cells in which a perovskite compound is used as a
light absorber often significantly decrease in highly humid
environments.
[0008] An object of the present invention is to provide a
photoelectric conversion element which has a perovskite compound in
a photosensitive layer as a light absorber and has excellent
moisture resistance. In addition, another object of the present
invention is to provide a solar cell in which the photoelectric
conversion element is used. In addition, a still another object of
the present invention is to provide a composition preferable for
forming the photosensitive layer in the photoelectric conversion
element.
[0009] The present inventors found that, when an organic cation
having a silyl group is used as at least some of organic cations in
photoelectric conversion elements or solar cells in which a
perovskite compound having organic cations, specific metallic
cations, and anions is used as a light absorber, photoelectric
conversion elements or solar cells having a photoelectric
conversion efficiency that does not easily decrease even in highly
humid environments can be obtained. The present invention has been
completed by repeating studies on the basis of the above-described
finding.
[0010] That is, the above-described objects of the present
invention have been achieved by the following means.
[1] A photoelectric conversion element comprising: a first
electrode having a photosensitive layer including a light absorber
on a conductive support; and a second electrode facing the first
electrode, in which the light absorber includes a compound having a
perovskite-type crystal structure including organic cations,
cations of a metallic atom other than elements belonging to Group I
of the periodic table, and anions, and at least some of the organic
cations constituting the compound are organic cations having a
silyl group. [2] The photoelectric conversion element according to
[1], in which the organic cation having a silyl group is
represented by Formula (1),
R.sup.1.sub.3Si-L-NR.sup.2.sub.3.sup.+ Formula (1)
[0011] in the formula, R.sup.1 represents a hydrogen atom, an alkyl
group, a cycloalkyl group, an alkenyl group, an alkynyl group, an
alkoxy group, an aryl group, a heteroaryl group, or an aliphatic
heterocyclic group, R.sup.2 represents a hydrogen atom, an alkyl
group, a cycloalkyl group, an alkenyl group, an alkynyl group, an
aryl group, a heteroaryl group, or an aliphatic heterocyclic group,
and L represents a divalent linking group.
[3] The photoelectric conversion element according to [2], in which
R.sup.1 is an alkyl group, an aryl group, or a heteroaryl group.
[4] The photoelectric conversion element according to [2] or [3],
in which L is a divalent linking group selected from an alkylene
group, a cycloalkylene group, an alkenylene group, an alkynylene
group, an arylene group, a heteroarylene group, --O--, --S--, and
--NR.sup.L-- or a divalent linking group formed by combining two or
more linking groups described above, and R.sup.L represents a
hydrogen atom or an alkyl group. [5] The photoelectric conversion
element according to [4], in which L is an alkylene group, an
arylene group, or a divalent linking group formed of a combination
of an alkylene group and an arylene group. [6] The photoelectric
conversion element according to any one of [2] to [5], in which the
organic cation having a silyl group represented by Formula (1) has
an alkylene group in L, and L and NR.sup.2.sub.3.sup.+ are linked
to each other through the alkylene group. [7] The photoelectric
conversion element according to any one of [1] to [6], in which the
compound having a perovskite-type crystal structure has organic
cations not having a silyl group. [8] The photoelectric conversion
element according to [7], in which, in the compound having a
perovskite-type crystal structure, a molar ratio of the organic
cations not having a silyl group to the organic cations having a
silyl group satisfies the following expression,
19.ltoreq.[organic cations not having silyl group]/[organic cations
having silyl group].ltoreq.499.
[9] The photoelectric conversion element according to [8], in
which, in the compound having a perovskite-type crystal structure,
the molar ratio of the organic cations not having a silyl group to
the organic cations having a silyl group satisfies the following
expression,
49.ltoreq.[organic cations not having silyl group]/[organic cations
having silyl group].ltoreq.199.
[10] A solar cell using the photoelectric conversion element
according to any one of [1] to [9]. [11] A composition comprising:
a compound represented by Formula (1a); and a halogenated
metal,
R.sup.1.sub.3Si-L-NR.sup.2.sub.3Hal Formula (1a)
[0012] in the formula, R.sup.1 represents a hydrogen atom, an alkyl
group, a cycloalkyl group, an alkenyl group, an alkynyl group, an
alkoxy group, an aryl group, a heteroaryl group, or an aliphatic
heterocyclic group, R.sup.2 represents a hydrogen atom, an alkyl
group, a cycloalkyl group, an alkenyl group, an alkynyl group, an
aryl group, a heteroaryl group, or an aliphatic heterocyclic group,
L represents a divalent linking group, and Hal represents a halogen
atom.
[12] The composition according to [11] which is used to form a
photosensitive layer in manufacturing of the photoelectric
conversion element according to any one of [1] to [9].
[0013] In the present specification, regarding individual chemical
formulae, there are cases in which a part of the chemical formula
is expressed as a rational formula for understanding of the
chemical structures of perovskite compounds. Accordingly, in the
individual chemical formulae, partial structures are called groups
(substituents), ions, atoms, or the like; however, in the present
specification, there are cases in which the partial structures will
refer to element groups or elements constituting groups
(substituents) or ions represented by the above-illustrated
formulae in addition to groups (substituents), ions, atoms, or the
like.
[0014] In the present specification, the expression of compounds is
used to indicate not only the compounds themselves but also salts
or ions thereof. Furthermore, groups or compounds that are not
clearly described as being substituted or unsubstituted refer to
groups or compounds having an arbitrary substituent as long as
desired effects are exhibited.
[0015] In the present specification, when there are a plurality of
substituents and the like expressed using a specific reference
symbol or a plurality of substituents and the like are specified at
the same time, the respective substituents and the like may be
identical to or different from each other unless particularly
otherwise described. What has been described above is also true for
the specification regarding the number of substituents and the
like. In addition, rings, for example, alicycles, aromatic rings,
and hetero rings may be further fused together and thus form a
fused ring.
[0016] In addition, in the present specification, numerical ranges
expressed using "to" include numerical values before and after the
"to" as the lower limit value and the upper limit value.
[0017] The photoelectric conversion element and the solar cell of
the present invention are excellent in terms of moisture resistance
while having a constitution in which a perovskite compound is
provided as a light absorber. In addition, the composition of the
present invention can be preferably used to form photosensitive
layers in the manufacturing of the photoelectric conversion element
of the present invention.
[0018] The above-described and other characteristics and advantages
of the present invention will be further clarified from the
following description with appropriate reference to the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a cross sectional view schematically illustrating
a preferred aspect of a photoelectric conversion element of the
present invention.
[0020] FIG. 2 is a cross sectional view schematically illustrating
a preferred aspect of the photoelectric conversion element of the
present invention including a thick photosensitive layer.
[0021] FIG. 3 is a cross sectional view schematically illustrating
another preferred aspect of the photoelectric conversion element of
the present invention.
[0022] FIG. 4 is a cross sectional view schematically illustrating
still another preferred aspect of the photoelectric conversion
element of the present invention.
[0023] FIG. 5 is a cross sectional view schematically illustrating
far still another preferred aspect of the photoelectric conversion
element of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Photoelectric Conversion Element
[0024] A photoelectric conversion element of the present invention
has a first electrode having a conductive support and a
photosensitive layer including a light absorber and a second
electrode facing the first electrode. Here, the first electrode and
the second electrode facing each other refers to both of an aspect
in which the first electrode and the second electrode are laminated
in a state of being in contact with each other and an aspect in
which the first electrode and the second electrode are laminated
through another layer (that is, an aspect in which the first
electrode and the second electrode are provided so as to face each
other while the first electrode and the second electrode sandwich
another layer).
[0025] The photoelectric conversion element of the present
invention preferably has a hole transport layer provided between
the first electrode and the second electrode. The photosensitive
layer and the second electrode are provided in this order on the
conductive support. That is, in a case in which the photoelectric
conversion element has the hole transport layer, the photosensitive
layer, the hole transport layer, and the second electrode are
preferably provided on the conductive support in this order.
[0026] In addition, the hole transport layer may be provided
between the conductive support and the photosensitive layer. In
this case, the hole transport layer, the photosensitive layer, and
the second electrode are provided on the conductive support in this
order.
[0027] The light absorber includes at least one perovskite compound
described below. The light absorber may also include a light
absorber other than the perovskite compound together with the
perovskite compound. Examples of the light absorber other than the
perovskite compound include metallic complex dyes and organic
dyes.
[0028] In the present invention, "the photosensitive layer being
provided on the conductive support" means that the photosensitive
layer is provided in contact with the surface of the conductive
support or the photosensitive layer is provided above the surface
of the conductive support through another layer.
[0029] In the aspect in which the photosensitive layer is provided
above the surface of the conductive support through another layer,
examples of the layer provided between the conductive support and
the photosensitive layer include a porous layer, a blocking layer,
an electron transport layer, a hole transport layer, and the
like.
[0030] In the present invention, examples of the aspect in which
the photosensitive layer is provided above the surface of the
conductive support through another layer include an aspect in which
the photosensitive layer is provided on the surface of a porous
layer in a thin film shape or the like (refer to FIG. 1), an aspect
in which the photosensitive layer is provided to be thick on the
surface of a porous layer (refer to FIG. 2), an aspect in which the
photosensitive layer is provided to be thin on the surface of a
blocking layer, an aspect in which the photosensitive layer is
provided on the surface of a blocking layer in a thick film shape
(refer to FIG. 3), an aspect in which the photosensitive layer is
provided on the surface of an electron transport layer in a thin
film shape or thick film shape (refer to FIG. 4), and an aspect in
which the photosensitive layer is provided on the surface of a hole
transport layer in a thin film shape or thick film shape (refer to
FIG. 5). The photosensitive layer may be provided in a linear shape
or in a dispersed pattern, but is preferably provided in a film
shape.
[0031] There is no particular limitation regarding constitutions
other than constitutions specified in the present invention for the
photoelectric conversion element of the present invention, and
well-known constitutions relating to photoelectric conversion
elements and solar cells can be employed. Individual layers
constituting the photoelectric conversion element of the present
invention are designed according to their purposes and may be
formed in, for example, a monolayer or multilayers.
[0032] Hereinafter, preferred aspects of the photoelectric
conversion element of the present invention will be described.
[0033] In FIGS. 1 to 5, the same reference symbol indicates the
same constituent element (member).
[0034] Meanwhile, in FIGS. 1 and 2, fine particles forming a porous
layer 12 are illustrated in an enlarged manner. These fine
particles are preferably jammed with each other (accumulated or in
close contact with each other) in the horizontal direction and the
vertical direction with respect to a conductive support 11 and thus
form a porous structure.
[0035] In the present specification, in the case of being simply
described, a "photoelectric conversion element 10" refers to
photoelectric conversion elements 10A, 10B, 10C, 10D, and 10E
unless particularly otherwise described. This is also true for a
system 100 and a first electrode 1. In addition, in the case of
being simply described, a "photosensitive layer 13" refers to
photosensitive layers 13A, 13B, and 13C unless particularly
otherwise described. Similarly, in the case of being described as a
"hole transport layer 3", the "hole transport layer 3" refers to
hole transport layers 3A and 3B unless particularly otherwise
described.
[0036] Examples of the preferred aspects of the photoelectric
conversion element of the present invention include the
photoelectric conversion element 10A illustrated in FIG. 1. A
system 100A illustrated in FIG. 1 is a system in which the
photoelectric conversion element 10A is applied as a cell that
causes action means M (for example, an electric motor) to operate
through an external circuit 6.
[0037] The photoelectric conversion element 10A includes a first
electrode 1A, a second electrode 2, and the hole transport layer 3A
including a hole-transporting material described below between the
first electrode 1A and the second electrode 2.
[0038] The first electrode 1A includes the conductive support 11
made up of a support 11a and a transparent electrode 11b, the
porous layer 12, and the photosensitive layer 13A on the porous
layer 12. In addition, a blocking layer 14 is provided on the
transparent electrode 11b, and the porous layer 12 is formed on the
blocking layer 14. In the photoelectric conversion element 10A
including the porous layer 12 as described above, since the surface
area of the photosensitive layer 13A increases, it is assumed that
the charge separation and charge transfer efficiency improves.
[0039] The photoelectric conversion element 10B illustrated in FIG.
2 is a schematic illustration of a preferred aspect in which the
photosensitive layer 13A in the photoelectric conversion element
10A illustrated in FIG. 1 is provided to be thick. In this
photoelectric conversion element 10B, the hole transport layer 3B
is provided to be thin. The photoelectric conversion element 10B is
different from the photoelectric conversion element 10A illustrated
in FIG. 1 in terms of the film thicknesses of the photosensitive
layer 13B and the hole transport layer 3B, but is constituted in
the same manner as the photoelectric conversion element 10A except
for the film thicknesses.
[0040] The photoelectric conversion element 10C illustrated in FIG.
3 is a schematic illustration of another preferred aspect of the
photoelectric conversion element of the present invention. The
photoelectric conversion element 10C is different from the
photoelectric conversion element 10B illustrated in FIG. 2 in terms
of the porous layer 12 not being provided, but is constituted in
the same manner as the photoelectric conversion element 10B except
for what has been described above. That is, in the photoelectric
conversion element 10C, the photosensitive layer 13C is formed on
the surface of the blocking layer 14 in a thick film shape.
[0041] The photoelectric conversion element 10D illustrated in FIG.
4 is a schematic illustration of still another preferred aspect of
the photoelectric conversion element of the present invention. The
photoelectric conversion element 10D is different from the
photoelectric conversion element 10C illustrated in FIG. 3 in terms
of the provision of an electron transport layer 15 instead of the
blocking layer 14, but is constituted in the same manner as the
photoelectric conversion element 10C except for what has been
described above. The first electrode 1D has the conductive support
11 and the electron transport layer 15 and the photosensitive layer
13C which are sequentially formed on the conductive support 11.
This photoelectric conversion element 10D is preferred since the
respective layers can be formed using organic materials. Therefore,
the productivity of the photoelectric conversion element improves,
and furthermore, thickness reduction or flexibilization becomes
possible.
[0042] The photoelectric conversion element 10E illustrated in FIG.
5 is a schematic illustration of far still another preferred aspect
of the photoelectric conversion element of the present invention. A
system 100E including the photoelectric conversion element 10E is,
similar to the system 100A, a system that is applied as a cell.
[0043] The photoelectric conversion element 10E has a first
electrode 1E, the second electrode 2, and the electron transport
layer 4 between the first electrode 1E and the second electrode 2.
The first electrode 1E has the conductive support 11 and the hole
transport layer 16 and the photosensitive layer 13C which are
sequentially formed on the conductive support 11. This
photoelectric conversion element 10E is preferred since, similar to
the photoelectric conversion element 10D, the respective layers can
be formed using organic materials.
[0044] In the present invention, the system 100 to which the
photoelectric conversion element 10 is applied functions as a solar
cell in the following manner.
[0045] That is, in the photoelectric conversion element 10A, light
that has passed through the conductive support 11 or the second
electrode 2 and has entered the photosensitive layer 13 excites a
light absorber. The excited light absorber has high-energy
electrons and is capable of emitting the electrons. The light
absorber which has emitted high-energy electrons turns into an
oxidant.
[0046] In the photoelectric conversion elements 10A to 10D,
electrons emitted from the light absorber migrate among the light
absorber particles and reach the conductive support 11. At this
time, the light absorber that has emitted electrons having a high
energy turns into an oxidant. The electrons that have reached the
conductive support 11 do their work in the external circuit 6 and
then return to the photosensitive layer 13 through the second
electrode 2 (in a case in which the hole transport layer 3 is
provided, through the hole transport layer 3 in addition to the
second electrode). The light absorber is reduced by the electrons
which have returned to the photosensitive layer 13.
[0047] Meanwhile, in the photoelectric conversion element 10E,
electrons emitted from the light absorber reach the second
electrode 2 from the photosensitive layer 13C through the electron
transport layer 4, do their work in the external circuit 6, and
then return to the photosensitive layer 13 through the conductive
support 11. The light absorber is reduced by the electrons which
have returned to the photosensitive layer 13.
[0048] In the photoelectric conversion element 10, the system 100
functions as a solar cell by repeating the cycle of the
above-described excitation of the light absorber and electron
migration.
[0049] In the photoelectric conversion elements 10A to 10D, the
flow direction of electrons from the photosensitive layer 13 to the
conductive support 11 varies depending on the presence or absence,
kind, and the like of the porous layer 12. In the photoelectric
conversion element 10 of the present invention, electron conduction
in which electrons migrate among the light absorber particles
occurs. Therefore, in a case in which the porous layer 12 is
provided, the porous layer 12 can be formed of an insulating body
other than semiconductors in the related art. In a case in which
the porous layer 12 is formed of a semiconductor, electron
conduction in which electrons migrate inside or among semiconductor
fine particles in the porous layer 12 also occurs. On the other
hand, in a case in which the porous layer 12 is formed of an
insulating body, electron conduction does not occur in the porous
layer 12. In a case in which the porous layer 12 is formed of an
insulating body, in a case in which aluminum oxide
(Al.sub.2O.sub.3) fine particles are used as insulating body fine
particles, a relatively high electromotive force (Voc) is
obtained.
[0050] Meanwhile, in a case in which the blocking layer 14, like
other layers, is formed of a conductor or a semiconductor as well,
electron conduction occurs in the blocking layer 14.
[0051] In addition, electron conduction occurs even in the electron
transport layer 15.
[0052] The photoelectric conversion element and the solar cell of
the present invention are not limited to the above-described
preferred aspects, and the constitutions and the like of the
respective aspects can be appropriately combined together within
the scope of the gist of the present invention.
[0053] In the present invention, materials and the respective
members which are used in the photoelectric conversion element and
the solar cell can be prepared using ordinary methods except for
the light absorber. Regarding photoelectric conversion elements or
solar cells in which the perovskite compound is used, it is
possible to refer to, for example, Science, 2012, vol. 338, pp. 643
to 647. In addition, regarding dye sensitized solar cells, it is
possible to refer to, for example, JP2001-291534A, the
specification of U.S. Pat. No. 4,927,721A, the specification of
U.S. Pat. No. 4,684,537A, the specification of U.S. Pat. No.
5,084,365A, the specification of U.S. Pat. No. 5,350,644A, the
specification of U.S. Pat. No. 5,463,057A, the specification of
U.S. Pat. No. 5,525,440A, JP1995-249790A (JP-H7-249790A),
JP2004-220974A, and JP2008-135197A.
[0054] Hereinafter, preferred aspects of the main members and
compounds of the photoelectric conversion element and the solar
cell of the present invention will be described.
[0055] <First Electrode 1>
[0056] The first electrode 1 includes the conductive support 11 and
the photosensitive layer 13 and functions as a working electrode in
the photoelectric conversion element 10.
[0057] As illustrated in FIGS. 1 to 5, the first electrode 1
preferably includes the porous layer 12, the blocking layer 14, and
at least one layer of the electron transport layer 15 or the hole
transport layer 16.
[0058] The first electrode 1 preferably includes at least the
blocking layer 14 in terms of short circuit prevention and more
preferably includes the porous layer 12 and the blocking layer 14
in terms of light absorption efficiency and short circuit
prevention.
[0059] In addition, the first electrode 1 preferably includes the
electron transport layer 15 or the hole transport layer 16 since
the first electrode can be formed of an organic material.
[0060] --Conductive Support 11--
[0061] The conductive support 11 is not particularly limited as
long as the conductive support is conductive and is capable of
supporting the photosensitive layer 13 or the like. The conductive
support 11 preferably has a constitution in which the conductive
support is formed of a conductive material, for example, metal or a
constitution in which the glass or plastic support 11a and the
transparent electrode 11b formed on the surface of the support 11a
as a conductive film are provided.
[0062] Among these, the conductive support 11 in which a film of
the transparent electrode 11b is formed by applying a conductive
metallic oxide onto the surface of the glass or plastic support 11a
as illustrated in FIGS. 1 to 5 is more preferred. Examples of the
support 11a formed of plastic include transparent polymer films
described in Paragraph 0153 of JP2001-291534A. As a material used
to form the support 11a, it is possible to use, in addition to
glass or plastic, ceramics (JP2005-135902A) or conductive resins
(JP2001-160425A). The metallic oxide is preferably a tin oxide (TO)
and particularly preferably an indium-tin oxide (a tin-doped indium
oxide, ITO) or a fluorine-doped tin oxide such as a fluorine-doped
tin oxide (FTO). At this time, the amount of the metallic oxide
applied is preferably 0.1 to 100 g per square meter of the surface
area of the support 11a. In a case in which the conductive support
11 is used, light preferably enters the conductive support through
the support 11a side.
[0063] The conductive support 11 is preferably substantially
transparent. In the present invention, "being substantially
transparent" means that the transmittance of light (having a
wavelength of 300 to 1,200 nm) is 10% or higher, preferably 50% or
higher, and particularly preferably 80% or higher.
[0064] The thicknesses of the support 11a and the conductive
support 11 are not particularly limited and are set to appropriate
thicknesses. For example, the thicknesses are preferably 0.01 .mu.m
to 10 mm, more preferably 0.1 .mu.m to 5 mm, and particularly
preferably 0.3 .mu.m to 4 mm.
[0065] In a case in which the transparent electrode 11b is
provided, the film thickness of the transparent electrode 11b is
not particularly limited and is, for example, preferably 0.01 to 30
.mu.m, more preferably 0.03 to 25 .mu.m, and particularly
preferably 0.05 to 20 .mu.m.
[0066] The conductive support 11 or the support 11a may have a
light management function on the surface. For example, the
conductive support 11 or the support 11a may have on the surface an
antireflection film obtained by alternately laminating
high-refractive index films and low-refractive index oxide films
which is described in JP2003-123859A or may have a light guide
function described in JP2002-260746A.
[0067] --Blocking Layer 14--
[0068] In the present invention, as in the photoelectric conversion
elements 10A to 10C, the blocking layer 14 is preferably provided
on the surface of the transparent electrode 11b, that is, between
the conductive support 11 and the porous layer 12, the
photosensitive layer 13, the hole transport layer 3, or the
like.
[0069] In the photoelectric conversion element and the solar cell,
for example, in a case in which the photosensitive layer 13 or the
hole transport layer 3 and the transparent electrode 11b are
electrically connected with each other, reverse currents are
generated. The blocking layer 14 performs a function of preventing
these reverse currents. The blocking layer 14 is also referred to
as a short circuit prevention layer.
[0070] The blocking layer may also be provided in a case in which
the photoelectric conversion element includes an electron transport
layer. For example, in the case of the photoelectric conversion
element 10D, the blocking layer may be provided between the
conductive support 11 and the electron transport layer 15, and in
the case of the photoelectric conversion element 10E, the blocking
layer may be provided between the second electrode 2 and the
electron transport layer 4.
[0071] A material used to form the blocking layer 14 is not
particularly limited as long as the material is capable of
performing the above-described function, but is preferably a
substance which transmits visible light and is insulating with
respect to the conductive support 11 (the transparent electrode
11b). The "substance insulating with respect to the conductive
support 11 (the transparent electrode 11b)" specifically refers to
a compound having an energy level of the conduction band which is
equal to or higher than the energy level of the conduction band of
a material used to form the conductive support 11 (a metallic oxide
used to form the transparent electrode 11b) and is lower than the
energy level of the conduction band of a material constituting the
porous layer 12 or the ground state of the light absorber (n-type
semiconductor compound).
[0072] Examples of a material used to form the blocking layer 14
include silicon oxide, magnesium oxide, aluminum oxide, calcium
carbonate, polyvinyl alcohols, polyurethanes, and the like. In
addition, the material may be a material that is ordinarily used as
a photoelectric conversion material, and examples thereof include
titanium oxide, tin oxide, niobium oxide, tungsten oxide, and the
like. Among these, titanium oxide, tin oxide, magnesium oxide,
aluminum oxide, and the like are preferred.
[0073] The film thickness of the blocking layer 14 is preferably
0.001 to 10 .mu.m, more preferably 0.005 to 1 .mu.m, and
particularly preferably 0.01 to 0.1 .mu.m.
[0074] In the present invention, the film thicknesses of the
respective layers can be measured by observing cross sections of
the photoelectric conversion element 10 using a scanning electron
microscope (SEM) or the like.
[0075] --Porous Layer 12--
[0076] In the present invention, as in the photoelectric conversion
elements 10A and 10B, the porous layer 12 is preferably provided on
the transparent electrode 11b. In a case in which the photoelectric
conversion element includes the blocking layer 14, the porous layer
12 is preferably formed on the blocking layer 14.
[0077] The porous layer 12 is a layer that functions as a scaffold
for carrying the photosensitive layer 13 on the surface. In solar
cells, in order to increase the light absorption efficiency, it is
preferable to increase the surface area of at least a portion
receiving light such as sunlight, and it is preferable to increase
the surface area of the porous layer 12 as a whole.
[0078] The porous layer 12 is preferably a fine particle layer
having pores which is formed of fine particles of a material used
to form the porous layer 12 being accumulated or in close contact
with each other. The porous layer 12 may be a fine particle layer
formed of two or more kinds of many fine particles being
accumulated together. In a case in which the porous layer 12 is a
fine particle layer having pores, it is possible to increase the
amount of the light absorber carried (adsorption amount).
[0079] In order to increase the surface area of the porous layer
12, it is preferable to increase the surface area of individual
fine particles that constitute the porous layer 12. In the present
invention, the surface area of fine particles used to form the
porous layer 12 in a state in which the fine particles are applied
onto the conductive support 11 and the like is preferably 10 or
more times and more preferably 100 or more times the projected
area. The upper limit thereof is not particularly limited, but is,
generally, approximately 5,000 times. Regarding the particle
diameters of the fine particles used to form the porous layer 12,
the average particle diameter of the diameters of equivalent
circles of the projected areas is preferably 0.001 to 1 .mu.m for
the primary particles. In a case in which the porous layer 12 is
formed using a dispersion of the fine particles, the average
particle diameter of the fine particles is preferably 0.01 to 100
.mu.m in terms of the average particle diameter in the
dispersion.
[0080] For the material used to form the porous layer 12, there is
no particular limitation regarding conductivity, and thus the
material may be an insulating body (insulating material), a
conductive material, or a semiconductor (semi-conductive
material).
[0081] As the material used to form the porous layer 12, it is
possible to use, for example, chalcogenides (for example, oxides,
sulfides, selenides, and the like) of metal, compounds having a
perovskite-type crystal structure (except for light absorbers
described below), oxides of silicon (for example, silicon dioxide
and zeolite), or carbon nanotubes (including carbon nanowires,
carbon nanorods, and the like).
[0082] The chalcogenides of metal are not particularly limited, and
preferred examples thereof include individual oxides of titanium,
tin, zinc, tungsten, zirconium, hafnium, strontium, indium, cerium,
yttrium, lanthanum, vanadium, niobium, aluminum, or tantalum,
cadmium sulfide, cadmium selenide, and the like. Examples of the
crystal structure of the chalcogenides of metal include an
anatase-type crystal structure, a brookite-type crystal structure,
and a rutile-type crystal structure, and an anatase-type crystal
structure and a brookite-type crystal structure are preferred.
[0083] The compounds having a perovskite-type crystal structure are
not particularly limited, and examples thereof include transition
metal oxides and the like. Examples thereof include strontium
titanate, calcium titanate, barium titanate, lead titanate, barium
zirconate, barium stannate, lead zirconate, strontium zirconate,
strontium tantalate, potassium niobate, bismuth ferrate, barium
strontium titanate, lanthanum barium titanate, calcium titanate,
sodium titanate, and bismuth titanate. Among these, strontium
titanate, calcium titanate, and the like are preferred.
[0084] The carbon nanotubes have a shape obtained by rolling a
carbon film (graphene sheet) in a tubular shape. Carbon nanotubes
are classified into single-walled carbon nanotubes (SWCNT) obtained
by coiling one graphene sheet in a cylindrical shape, double-walled
carbon nanotubes (DWCNT) obtained by coiling two graphene sheets in
a concentric shape, and multi-walled carbon nanotubes (MWCNT)
obtained by coiling multiple graphene sheets in a concentric shape.
As the porous layer 12, any carbon nanotubes can be used without
any particular limitation.
[0085] Among these, the material used to form the porous layer 12
is preferably an oxide of titanium, tin, zinc, zirconium, aluminum,
or silicon or a carbon nanotube and more preferably titanium oxide
or aluminum oxide.
[0086] The porous layer 12 may be formed of at least one of the
chalcogenide of metal, the compound having a perovskite-type
crystal structure, the oxide of silicon, or the carbon nanotube or
may be formed of a plurality thereof.
[0087] The film thickness of the porous layer 12 is not
particularly limited and is generally in a range of 0.1 to 100
.mu.m, and, in the case of being used as a solar cell, the film
thickness is preferably 0.1 to 50 .mu.m and more preferably 0.2 to
30 .mu.m.
[0088] --Electron Transport Layer 15--
[0089] In the present invention, as in the photoelectric conversion
element 10D, the electron transport layer 15 is preferably provided
on the surface of the transparent electrode 11b.
[0090] The electron transport layer 15 has a function of
transporting electrons generated in the photosensitive layer 13 to
the conductive support 11. The electron transport layer 15 is
formed of an electron-transporting material capable of exhibiting
the above-described function. The electron-transporting material is
not particularly limited and is preferably an organic material
(organic electron-transporting material). Examples of the organic
electron-transporting material include fullerene compounds such as
[6,6]-phenyl-C61-butyric acid methyl ester (PCBM), perylene
compounds such as perylene tetracarboxylic diimide (PTCDI),
additionally, low-molecular-weight compounds such as
tetracyanoquinodimethane (TCNQ), high-molecular-weight compounds,
and the like.
[0091] The film thickness of the electron transport layer 15 is not
particularly limited and is preferably 0.001 to 10 .mu.m and more
preferably 0.01 to 1 .mu.m.
[0092] --Hole Transport Layer 16--
[0093] In the present invention, as in the photoelectric conversion
element 10E, the hole transport layer 16 is preferably provided on
the surface of the transparent electrode 11b.
[0094] The hole transport layer 16 is the same as the hole
transport layer 3 described below except for the fact that the hole
transport layer is formed at a different location.
[0095] --Photosensitive Layer (Light-Absorbing Layer) 13--
[0096] In the photosensitive layer 13, a perovskite compound
described below is preferably provided as a light absorber on the
surface (including the inner surfaces in a case in which surfaces
provided with the photosensitive layer 13 are uneven) of each of
the porous layer 12 (in the photoelectric conversion elements 10A
and 10B), the blocking layer 14 (in the photoelectric conversion
element 10C), the electron transport layer 15 (in the photoelectric
conversion element 10D), and the hole transport layer 16 (in the
photoelectric conversion element 10E).
[0097] In the present invention, the light absorber needs to
contain at least one perovskite compound described below and may
contain two or more perovskite compounds.
[0098] The photosensitive layer 13 may be a single layer or a
laminate of two or more layers. In a case in which the
photosensitive layer 13 is a laminate structure of two or more
layers, the laminate structure may be a laminate of layers made of
mutually different light absorbers or may have an interlayer
including a hole-transporting material laminated between the
photosensitive layer and the photosensitive layer.
[0099] A form of the photosensitive layer 13 being present on the
conductive support 11 is as described above. The photosensitive
layer 13 is preferably provided on the surface of each of the
above-described layers so that excited electrons flow into the
conductive support 11. At this time, the photosensitive layer 13
may be provided on the entire surface or on a part of the surface
of the above-described layers.
[0100] The film thickness of the photosensitive layer 13 is
appropriately set according to aspects of the photosensitive layer
13 provided on the conductive support 11 and is not particularly
limited. The film thickness of the photosensitive layer 13 (in a
case in which the porous layer 12 is provided, the total film
thickness including the film thickness of the porous layer 12) is,
for example, preferably 0.1 to 100 .mu.m, more preferably 0.1 to 50
.mu.m, and particularly preferably 0.2 to 30 .mu.m.
[0101] In the present invention, in a case in which the
photosensitive layer is provided in a thick film shape (the
photosensitive layers 13B and 13C), the light absorber included in
the photosensitive layer also functions as a hole-transporting
material.
[0102] [Light Absorber in Photosensitive Layer]
[0103] The photosensitive layer 13 includes, as a light absorber, a
perovskite compound having organic cations, cations of metallic
atoms other than elements belonging to Group I of the periodic
table, and anions.
[0104] Some of the organic cations constituting the perovskite
compound being used in the present invention are organic cations
having a silyl group. When the perovskite compound has the organic
cations having a silyl group in the crystal structure, it is
possible to significantly enhance the moisture resistance of
photoelectric conversion elements to be obtained. The reason
thereof is not clear, but is assumed that the silyl group serves as
a hydrophobic component and effectively develops a barrier action
against moisture. The organic cation having a silyl group is
preferably represented by Formula (1).
R.sup.1.sub.3Si-L-NR.sup.2.sub.3.sup.+ Formula (1)
[0105] In Formula (1), R.sup.1 represents a hydrogen atom or a
group selected from an alkyl group, a cycloalkyl group, an alkenyl
group, an alkynyl group, an alkoxy group, an aryl group, a
heteroaryl group, and an aliphatic heterocyclic group.
[0106] Examples of the alkyl group that can be employed as R.sup.1
include linear alkyl groups and branched alkyl groups. The number
of carbon atoms in the alkyl group is preferably 1 to 18, more
preferably 1 to 6, and still more preferably 1 to 3. Specific
examples of preferred alkyl groups include methyl, ethyl, propyl,
isopropyl, n-butyl, t-butyl, pentyl, and hexyl.
[0107] In Formula (1), two R.sup.1's which are linked to the Si
atom and present adjacent to each other may be linked to each other
and form a ring. In this case, the formed ring may have a hetero
atom as a ring-constituting atom.
[0108] In the cycloalkyl group that can be employed as R.sup.1, the
number of carbon atoms is preferably 3 to 8. Specific examples of
preferred cycloalkyl groups include cyclopropyl, cyclopentyl, and
cyclohexyl.
[0109] Examples of the alkenyl group that can be employed as
R.sup.1 include linear alkenyl groups and branched alkenyl groups.
The number of carbon atoms in the alkenyl group is preferably 2 to
18, more preferably 2 to 7, and still more preferably 2 to 5.
Specific examples of preferred alkenyl groups include vinyl, allyl,
butenyl, and hexenyl.
[0110] Examples of the alkynyl group that can be employed as
R.sup.1 include linear alkynyl groups and branched alkynyl groups.
The number of carbon atoms in the alkynyl group is preferably 2 to
18, more preferably 2 to 7, and still more preferably 2 to 5.
Specific examples of preferred alkynyl groups include ethynyl,
butynyl, and hexynyl.
[0111] Examples of the alkoxy group that can be employed as R.sup.1
include linear alkoxy groups and branched alkoxy groups. The alkyl
portion in the alkoxy group is the same as the alkyl group that can
be employed as R.sup.1 described above, and a preferred aspect is
also identical.
[0112] In the aryl group that can be employed as R.sup.1, the
number of carbon atoms is preferably 6 to 14. Specific examples of
preferred aryl groups include phenyl and naphthyl, and phenyl is
more preferred.
[0113] Examples of the heteroaryl group that can be employed as
R.sup.1 include groups formed of an aromatic hetero ring alone and
groups formed of a condensed hetero ring obtained by condensing
another ring, for example, an aromatic ring, an aliphatic ring, or
a hetero ring with the aromatic hetero ring.
[0114] The ring-constituting hetero atom constituting the aromatic
hetero ring is preferably a nitrogen atom, an oxygen atom, or a
sulfur atom. In addition, regarding the number of ring members of
the aromatic hetero ring, five-membered rings or six-membered rings
are preferred.
[0115] Examples of the five-membered aromatic hetero ring and the
condensed hetero ring including the five-membered aromatic hetero
ring include a pyrrole ring, an imidazole ring, a pyrazole ring, an
oxazole ring, a thiazole ring, a triazole ring, a furan ring, a
thiophene ring, a benzimidazole ring, a benzoxazole ring, a
benzothiazole ring, an indoline ring, and an indazole ring. In
addition, examples of the six-membered aromatic hetero ring and the
condensed hetero ring including the six-membered aromatic hetero
ring include a pyridine ring, a pyrimidine ring, a pyrazine ring, a
triazine ring, a quinoline ring, and a quinazoline ring.
[0116] In the aliphatic heterocyclic group that can be employed as
R.sup.1, the number of carbon atoms is preferably 0 to 24 and more
preferably 1 to 18. Specific examples of preferred aliphatic hetero
rings of the aliphatic heterocyclic group include a pyrrolidine
ring, an oxolane ring, a thiolane ring, a piperidine ring, an oxane
ring, a thiane ring, a piperazine ring, a morpholine ring, a
quinuclidine ring, an azetidine ring, an oxetane ring, an aziridine
ring, a dioxane ring, a pentamethylene sulfide ring, and the
like.
[0117] R.sup.1 may further have a substituent, and examples of the
substituent include the above-described substituent that can be
employed as R.sup.1. In addition, the substituent that R.sup.1 may
have is also preferably -L-NR.sup.2.sub.3.sup.+ in Formula (1).
[0118] R.sup.1 is preferably an alkyl group, an aryl group, or a
heteroaryl group and more preferably an alkyl group from the
viewpoint of more effectively developing the barrier action against
moisture.
[0119] In Formula (1), R.sup.2 represents a hydrogen atom or a
group selected from an alkyl group, a cycloalkyl group, an alkenyl
group, an alkynyl group, an aryl group, a heteroaryl group, and an
aliphatic heterocyclic group.
[0120] The alkyl group, the cycloalkyl group, the alkenyl group,
the alkynyl group, the aryl group, the heteroaryl group, and the
aliphatic heterocyclic group that can be employed as R.sup.2 are
respectively the same as the alkyl group, the cycloalkyl group, the
alkenyl group, the alkynyl group, the aryl group, the heteroaryl
group, and the aliphatic heterocyclic group that can be employed as
R.sup.1, and preferred aspects thereof are also identical. Two
R.sup.2's which are linked to the N atom and present adjacent to
each other may be linked to each other and form a ring. In this
case, the formed ring may have a hetero atom as a ring-constituting
atom.
[0121] R.sup.2 is preferably a hydrogen atom or an alkyl group and
more preferably a hydrogen atom.
[0122] In Formula (1), L is a divalent linking group. L is
preferably a divalent linking group selected from an alkylene
group, a cycloalkylene group, an alkenylene group, an alkynylene
group, an arylene group, a heteroarylene group, --O--, --S--, and
--NR.sup.L-- or a divalent linking group formed of a combination of
divalent linking groups selected from an alkylene group, a
cycloalkylene group, an alkenylene group, an alkynylene group, an
arylene group, a heteroarylene group, --O--, --S--, and
--NR.sup.L--. R.sup.L is a hydrogen atom or an alkyl group, this
alkyl group is the same as the above-described alkyl group that can
be employed as R.sup.1, and a preferred aspect thereof is also
identical.
[0123] Examples of the alkylene group that can be employed as L or
a part of L include linear alkylene groups and branched alkylene
groups. The number of carbon atoms in the alkylene group is
preferably 1 to 20, more preferably 1 to 15, still more preferably
1 to 10, still more preferably 1 to 5, and still more preferably 1
to 3. Specific examples of preferred alkylene groups include
methylene, ethylene, propylene, butylene, pentylene, and
hexylene.
[0124] In the cycloalkylene group that can be employed as L or a
part of L, the number of carbon atoms is preferably 3 to 8.
Specific examples of preferred cycloalkylene groups include
cyclopropylene, cyclpentylene, and cyclohexylene.
[0125] Examples of the alkenylene group that can be employed as L
or a part of L include linear alkenylene groups and branched
alkenylene groups. The number of carbon atoms in the alkenylene
group is preferably 2 to 20, more preferably 2 to 15, still more
preferably 2 to 10, still more preferably 2 to 5, and still more
preferably 2 or 3.
[0126] Examples of the alkynylene group that can be employed as L
or a part of L include linear alkynylene groups and branched
alkynylene groups. The number of carbon atoms in the alkynylene
group is preferably 2 to 20, more preferably 2 to 15, still more
preferably 2 to 10, far still more preferably 2 to 5, and
particularly preferably 2 to 4.
[0127] The number of carbon atoms in the arylene group that can be
employed as L or a part of L is preferably 6 to 14. The arylene
group is preferably phenylene or naphthylene and more preferably
phenylene.
[0128] In the heteroarylene group that can be employed as L or a
part of L, the number of carbon atoms is preferably 0 to 24 and
more preferably 1 to 18. Rings constituting the heteroarylene group
are preferably condensed hetero rings including a five-membered
aromatic hetero ring or a five-membered aromatic hetero ring or
condensed hetero rings including a six-membered aromatic hetero
ring or a six-membered aromatic hetero ring. Preferred examples of
the five-membered aromatic hetero ring, the condensed hetero rings
including the five-membered aromatic hetero ring, the six-membered
aromatic hetero ring, and the condensed hetero rings including the
six-membered aromatic hetero ring are the same as the preferred
aspects of the condensed hetero rings including the five-membered
aromatic hetero ring, the condensed hetero rings including the
five-membered aromatic hetero ring, the six-membered aromatic
hetero ring, and the condensed hetero rings including the
six-membered aromatic hetero ring described in the section of the
above-described heteroaryl group that can be employed as
R.sup.1.
[0129] Among these, L is preferably an alkylene group, a
cycloalkylene group, an alkenylene group, an alkynylene group, an
arylene group, a heteroarylene group, or a divalent linking group
formed of a combination of two or more (preferably two) groups
selected from an alkylene group, a cycloalkylene group, an
alkenylene group, an alkynylene group, an arylene group, and a
heteroarylene group. L is more preferably an alkylene group, an
arylene group, or a divalent linking group formed of a combination
of an alkylene group and an arylene group.
[0130] In a case in which the organic cation having a silyl group
represented by Formula (1) has an alkylene group in L, L and
NR.sup.2.sub.3.sup.+ are preferably linked to each other through
the alkylene group. That is, in a case in which the organic cation
having a silyl group represented by Formula (1) has an alkylene
group in L, the organic cation is preferably represented by
R.sup.1.sub.3Si-L.sup.1- L.sup.2-NR.sup.2.sub.3.sup.+. Here,
L.sup.1 represents a divalent linking group selected from a single
bond, a cycloalkylene group, an alkenylene group, an alkynylene
group, an arylene group, a heteroarylene group, --O--, --S--, and
--NR.sup.L--, and L.sup.2 represents an alkylene group. R.sup.1,
R.sup.2, and R.sup.L are respectively the same as R.sup.1, R.sup.2,
and R.sup.L described above, and preferred aspects thereof are also
identical. In addition, a preferred aspect of the alkylene group
L.sup.2 is the same as the above-described preferred aspect of the
alkylene group that can be employed as L.
[0131] The organic cation having a silyl group is also preferably
an organic cation represented by Formula (RI) in addition to the
organic cation represented by Formula (1).
##STR00001##
[0132] In Formula (RI), R.sup.1 and R.sup.2 each are the same as
R.sup.1 and R.sup.2 in Formula (1), and preferred aspects thereof
are also identical.
[0133] Hereinafter, specific examples of the organic cation having
a silyl group which the perovskite compound being used in the
present invention may have will be described, but the present
invention is not limited thereto. In the present specification, in
structural formulae, "Bu" represents butyl, and "Me" represents
methyl.
##STR00002## ##STR00003## ##STR00004## ##STR00005##
[0134] The organic cation constituting the perovskite compound
being used in the present invention preferably includes an organic
cation not having a silyl group in addition to the organic cation
having a silyl group. The organic cation not having a silyl group
is preferably an organic cation represented by Formula (2).
R.sup.A--NH.sub.3.sup.+ Formula (2)
[0135] In Formula (2), R.sup.A is preferably an alkyl group, a
cycloalkyl group, an alkenyl group, an alkynyl group, an aryl
group, a heteroaryl group, or a group that can be represented by
Formula (3). Among these, an alkyl group and the group that can be
represented by Formula (3) are more preferred, and an alkyl group
is still more preferred.
[0136] The alkyl group, the cycloalkyl group, the alkenyl group,
the alkynyl group, the aryl group, and the heteroaryl group that
can be employed by R.sup.A are the same as the alkyl group, the
cycloalkyl group, the alkenyl group, the alkynyl group, the aryl
group, and the heteroaryl group that can be respectively employed
by R.sup.1 in Formula (1) respectively, and preferred groups are
also identical thereto.
##STR00006##
[0137] In the formula, X.sup.a represents NR.sup.1c, an oxygen
atom, or a sulfur atom. R.sup.1b and R.sup.1c each independently
represent a hydrogen atom or a substituent. * represents a bonding
location with an N atom in Formula (2).
[0138] In the present invention, in a case in which the organic
cation not having a silyl group is an organic ammonium cation
formed by bonding R.sup.A and NH.sub.3.sup.+ in Formula (2), the
organic ammonium cation may have a resonance structure. For
example, in a case in which X.sup.a in the group that can be
represented by Formula (3) is NH (R.sup.1c is a hydrogen atom),
examples of the organic cation include not only organic ammonium
cations formed by bonding the group that can be represented by
Formula (3) and NH.sub.3.sup.+ but also organic amidinium cations
which are one of the resonance structures of the organic ammonium
cation. Examples of the organic amidinium cations include cations
represented by Formula (A.sup.am). Meanwhile, in the present
specification, there are cases in which the cations represented by
Formula (A.sup.am) are expressed as "R.sup.1bC(.dbd.NH)--NH.sub.3"
for convenience.
##STR00007##
[0139] In the group that can be represented by Formula (3), X.sup.a
represents NR.sup.1c, an oxygen atom, or a sulfur atom and is
preferably NR.sup.1c. Here, R.sup.1c represents a hydrogen atom or
substituent and is preferably a hydrogen atom, an alkyl group, a
cycloalkyl group, an alkenyl group, an alkynyl group, an aryl
group, or a heteroaryl group and more preferably a hydrogen
atom.
[0140] R.sup.1b represents a hydrogen atom or a substituent and is
preferably a hydrogen atom. Examples of a substituent that can be
employed by R.sup.1b include an amino group, an alkyl group, a
cycloalkyl group, an alkenyl group, an alkynyl group, an aryl
group, and a heteroaryl group.
[0141] An alkyl group, a cycloalkyl group, an alkenyl group, an
alkynyl group, an aryl group, and a heteroaryl group that can be
respectively employed by R.sup.1b and R.sup.1c are the same as the
alkyl group, the cycloalkyl group, the alkenyl group, the alkynyl
group, the aryl group, and the heteroaryl group that can be
respectively employed by R.sup.1 in Formula (1) respectively, and
preferred groups are also identical thereto.
[0142] Examples of the group that can be represented by Formula (3)
include a (thio)acyl group, a (thio)carbamoyl group, an imidoyl
group, and an amidino group.
[0143] Examples of the (thio)acyl group include an acyl group and a
thioacyl group. The acyl group is preferably an acyl group having a
total of 1 to 7 carbon atoms, and examples thereof include formyl,
acetyl (CH.sub.3C(.dbd.O)--), propionyl, hexanoyl, and the like.
The thioacyl group is preferably a thioacyl group having a total of
1 to 7 carbon atoms, and examples thereof include thioformyl,
thioacetyl (CH.sub.3C(.dbd.S)--), thiopropionyl, and the like.
[0144] Examples of the (thio)carbamoyl group include a carbamoyl
group (H.sub.2NC(.dbd.O)--) and thiocarbamoyl group
(H.sub.2NC(.dbd.S)--).
[0145] The imidoyl group is a group represented by
R.sup.1b--C(.dbd.NR.sup.1c)--, R.sup.1b and R.sup.1c each are
preferably a hydrogen atom or an alkyl group, and the alkyl group
is more preferably the same as the alkyl group as R.sup.1. Examples
thereof include formimidoyl (HC(.dbd.NH)--), acetoimidoyl
(CH.sub.3C(.dbd.NH)--), propionimidoyl
(CH.sub.3CH.sub.2C(.dbd.NH)--), and the like. Among these,
formimidoyl is preferred.
[0146] The amidino group as the group that can be represented by
Formula (3) has a structure in which R.sup.1b of the imidoyl group
is an amino group and R.sup.1c is a hydrogen atom
(--C(.dbd.NH)NH.sub.2).
[0147] In the crystal structure of the perovskite compound being
used in the present invention, the molar ratio of the organic
cations not having a silyl group to the organic cations having a
silyl group preferably satisfies Numerical Expression (i), more
preferably satisfies Numerical Expression (ii), and still more
preferably satisfies Numerical Expression (iii).
4.ltoreq.[organic cations not having silyl group]/[organic cations
having silyl group].ltoreq.999 Numerical Expression (i)
19.ltoreq.[organic cations not having silyl group]/[organic cations
having silyl group].ltoreq.499 Numerical Expression (ii)
49.ltoreq.[organic cations not having silyl group]/[organic cations
having silyl group].ltoreq.199 Numerical Expression (iii)
[0148] When the molar ratio of the organic cations not having a
silyl group to the organic cations having a silyl group satisfies
the above-described expression, it is possible to further enhance
the moisture resistance of photoelectric conversion elements.
[0149] The perovskite compound being used in the present invention
has cations of metallic atoms other than elements belonging to
Group I of the periodic table in the crystal structure. Examples of
the metallic atoms other than elements belonging to Group I of the
periodic table include metallic atoms such as calcium (Ca),
strontium (Sr), cadmium (Cd), copper (Cu), nickel (Ni), manganese
(Mn), iron (Fe), cobalt (Co), palladium (Pd), germanium (Ge), tin
(Sn), lead (Pb), ytterbium (Yb), europium (Eu), indium (In),
titanium (Ti), and bismuth (Bi), among these, at least one selected
from the group consisting of a Pb atom, a Cu atom, a Ge atom, and a
Sn atom is more preferred, a Pb atom or a Sn atom is still more
preferred, and a Pb atom is particularly preferred. The perovskite
compound being used in the present invention may have one or two or
more kinds of cations of metallic atoms other than elements
belonging to Group I of the periodic table in the crystal
structure. In the case of having two or more kinds of cations of
metallic atoms other than elements belonging to Group I of the
periodic table, the perovskite compound preferably has a Pb atom
and a Sn atom. In a case in which the perovskite compound has two
or more kinds of cations of metallic atoms other than elements
belonging to Group I of the periodic table, the presence fractions
of two or more kinds of these cations are not particularly
limited.
[0150] Anions constituting the perovskite compound being used in
the present invention may be monoatomic anions or polyatomic
anions. Examples of the monoatomic anions include anions of halogen
atoms. In addition, preferred examples of the polyatomic anions
include NCS.sup.-, NCO.sup.-, HO.sup.-, NO.sub.3.sup.-, and
COO.sup.-. Among these, the anions constituting the perovskite
compound are preferably anions of halogen atoms. Examples of the
halogen atoms include a fluorine atom, a chlorine atom, a bromine
atom, and an iodine atom, and a bromine atom or an iodine atom is
preferred.
[0151] The anions constituting the perovskite compound being used
in the present invention may be one kind of anions or two or more
kinds of anions. In a case in which the anions constituting the
perovskite compound is one kind of anions, anions of an iodine atom
are preferred. In addition, in a case in which the anions
constituting the perovskite compound are two kinds of anions,
aspects having anions of two or more kinds of halogen atoms is
preferred, and, among these, an aspect having two kinds of anions
of a chlorine atom and anions of an iodine atom is more preferred.
In a case in which the perovskite compound has two or more kinds of
anions, the proportions thereof are not particularly limited.
[0152] The perovskite compound being used in the present invention
may have cations of elements belonging to Group I of the periodic
table in the structure. The cations of elements belonging to Group
I of the periodic table are preferably a lithium ion (Li.sup.+), a
sodium ion (Na.sup.+), a potassium ion (K.sup.+), and a cesium ion
(Cs.sup.+), and, among these, Cs.sup.+ is more preferred.
[0153] The perovskite compound that is used in the present
invention has a perovskite-type crystal structure having the
respective constituent ions described above. The perovskite
compound that is used in the present invention is preferably a
perovskite compound represented by Formula (I).
A.sub.aM.sub.mX.sub.x Formula (I)
[0154] In the formula, A represents an element in Group I of the
periodic table or a cationic organic group. M represents a metallic
atom that is not an element in Group I of the periodic table. X
represents an anionic atom or anionic atomic group.
[0155] a represents 1 or 2, m represents 1, and a, m, and x satisfy
a+2m=x.
[0156] In the present specification, the cationic organic group
refers to an organic group being present as a cation in the
perovskite-type crystal structure, the anionic atom refers to an
atom being present as a monoatomic anion in the perovskite-type
crystal structure, and the anionic atomic group refers to an atomic
group being present as a polyatomic anion in the perovskite-type
crystal structure.
[0157] In Formula (I), an element A belonging to Group I of the
periodic table is present as a cation in the perovskite-type
crystal structure.
[0158] In Formula (I), a cationic organic group A is present as the
above-described organic cation in the perovskite-type crystal
structure.
[0159] In Formula (I), a metallic atom M is present in the
perovskite-type crystal structure as the above-described cation of
a metallic atom other than elements belonging to Group I of the
periodic table.
[0160] In Formula (I), an anionic atom X is present as the
above-described monoatomic anion in the perovskite-type crystal
structure.
[0161] In Formula (I), an anionic atom group X is present as the
above-described polyatomic anion in the perovskite-type crystal
structure.
[0162] In the perovskite compound represented by Formula (I), at
least a part of A is a cationic organic group having a silyl
group.
[0163] The perovskite compound being used in the present invention
may also be a mixture of a perovskite compound represented by
Formula (I) in which a is 1 and a perovskite compound represented
by Formula (I) in which a is 2.
[0164] The perovskite compound can be synthesized from MX.sub.2 and
AX. For example, the perovskite compound can be synthesized with
reference to Science, 2012, vol. 338, pp. 643 to 647. In addition,
the perovskite compound can be synthesized with appropriate
reference to Akihiro Kojima, Kenjiro Teshima, Yasuo Shirai, and
Tsutomu Miyasaka, "Organometal Halide Perovskites as Visible-Light
Sensitizers for Photovoltaic Cells", J. Am. Chem. Soc., 2009, 131
(17), pp. 6050 and 6051.
[0165] In the perovskite compound being used in the present
invention, the proportion of the total molar quantity of the
organic cation represented by Formula (1), the organic cation
represented by Formula (RI), the organic cation represented by
Formula (2), and the cations of metallic atoms other than elements
belonging to Group I of the periodic table in the total molar
quantity of the cations constituting the perovskite compound is
preferably 90 to 100% by mol and more preferably 95 to 100% by mol.
In addition, in the perovskite compound being used in the present
invention, the proportion of the total molar quantity of the anions
of the halogen atoms in the total molar quantity of the anions
constituting the perovskite compound is preferably 90 to 100% by
mol, more preferably 95 to 100% by mol, and still more preferably
98 to 100% by mol.
[0166] The amount of the light absorber used needs to be an amount
at which, out of the surface of the porous layer 12 or the blocking
layer 14, at least some of the surface on which light is incident
is covered and is preferably an amount at which the surface is
fully covered.
[0167] The content of the perovskite compound in the photosensitive
layer 13 is generally 1 to 100% by mass.
[0168] <Hole Transport Layer 3>
[0169] The photoelectric conversion element of the present
invention preferably has the hole transport layer 3 between the
first electrode and the second electrode.
[0170] The hole transport layer 3 has a function of supplementing
electrons to oxidants of the light absorber and is preferably a
solid-form layer. The hole transport layer 3 is preferably provided
between the photosensitive layer 13 in the first electrode 1 and
the second electrode 2.
[0171] A hole-transporting material that forms the hole transport
layer 3 is not particularly limited, and examples thereof include
inorganic materials such as CuI and CuNCS, organic
hole-transporting materials described in Paragraphs 0209 to 0212 of
JP2001-291534A, and the like. Preferred examples of the organic
hole-transporting material include conductive polymers such as
polythiophene, polyaniline, polypyrrole, and polysilane, spiro
compounds in which two rings share a central atom having a
tetrahedral structure such as C or Si, aromatic amine compounds
such as triarylamine, triphenylene compounds, nitrogen-containing
heterocyclic compounds, and liquid-crystalline cyano compounds.
[0172] The hole-transporting material is preferably an organic
hole-transporting material which can be applied in a solution and
turns into solid, and examples thereof include
2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9-spirobifluorene
(also referred to as Spiro-OMeTAD),
poly(3-hexylthiophene-2,5-diyl), 4-(diethylamino)benzoaldehyde,
diphenylhydrazone, polyethylene dioxythiophene (PEDOT), and the
like.
[0173] The film thickness of the hole transport layer 3 is not
particularly limited, but is preferably 50 .mu.m or less, more
preferably 1 nm to 10 .mu.m, still more preferably 5 nm to 5 .mu.m,
and particularly preferably 10 nm to 1 .mu.m.
[0174] In the present invention, in a case in which the porous
layer 12 is included, the total film thickness of the porous layer
12, the photosensitive layer 13, and the hole transport layer 3 is
not particularly limited, but is, for example, preferably 0.1 to
200 .mu.m, more preferably 0.1 to 50 .mu.m, and still more
preferably 0.2 to 5 .mu.m.
[0175] <Electron Transport Layer 4>
[0176] In the present invention, as the photoelectric conversion
element 10E, the electron transport layer 4 is preferably provided
between the photosensitive layer 13C and the second electrode
2.
[0177] The electron transport layer 4 is the same as the electron
transport layer 15 except for the fact that electrons are
transferred to the second electrode and the electron transport
layer is formed at a different location.
[0178] <Second Electrode 2>
[0179] The second electrode 2 functions as a positive electrode in
solar cells. The second electrode 2 is not particularly limited as
long as the second electrode is conductive and, generally, can be
provided with the same constitution as that of the conductive
support 11. In a case in which a sufficient strength is maintained,
the support 11a is not essentially required.
[0180] The structure of the second electrode 2 is preferably a
structure having a strong power-collection effect. In order to
allow light to reach the photosensitive layer 13, at least one of
the conductive support 11 or the second electrode 2 needs to be
substantially transparent. In the solar cell of the present
invention, it is preferable that the conductive support 11 is
transparent and sunlight enters the solar cell through the support
11a side. In this case, the second electrode 2 more preferably has
a property of reflecting light.
[0181] Examples a material used to form the second electrode 2
include metal such as platinum (Pt), gold (Au), nickel (Ni), copper
(Cu), silver (Ag), indium (In), ruthenium (Ru), palladium (Pd),
rhodium (Rh), iridium (Jr), osmium (Os), and aluminum (Al), the
above-described conductive metallic oxides, carbon materials,
conductive polymers, and the like. The carbon materials need to be
conductive materials formed of carbon atoms bonded together, and
examples thereof include fullerene, carbon nanotubes, graphite,
graphene, carbon black, and the like.
[0182] The second electrode 2 is preferably a thin film (including
a thin film obtained by means of vapor deposition) of metal or a
conductive metallic oxide or a glass or plastic substrate having
this thin film. The glass or plastic substrate is preferably a
glass substrate having a gold or platinum thin film or a glass
substrate on which platinum is vapor-deposited.
[0183] The film thickness of the second electrode 2 is not
particularly limited, but is preferably 0.01 to 100 .mu.m, more
preferably 0.01 to 10 .mu.m, and particularly preferably 0.01 to 1
.mu.m.
[0184] <Other Constitutions>
[0185] In the present invention, in order to prevent the first
electrode 1 and the second electrode 2 from coming into contact
with each other, a spacer or a separator can also be used instead
of the blocking layer 14 and the like or together with the blocking
layer 14 and the like.
[0186] In addition, a hole-blocking layer may be provided between
the second electrode 2 and the hole transport layer 3.
[0187] Solar Cell
[0188] The solar cell of the present invention is constituted using
the photoelectric conversion element of the present invention. For
example, as illustrated in FIGS. 1 to 5, the photoelectric
conversion element 10 constituted by providing the external circuit
6 can be used as a solar cell. As the external circuit which comes
into contact with the first electrode 1 (the conductive support 11)
and the second electrode 2, a well-known circuit can be used
without any particular limitation.
[0189] In order to prevent the deterioration, evaporation, and the
like of constituent substances, the solar cell of the present
invention preferably has a side surface that is sealed with a
polymer, an adhesive, or the like.
[0190] Method for Manufacturing Photoelectric Conversion Element
and Solar Cell
[0191] The photoelectric conversion element and the solar cell of
the present invention can be manufactured according to well-known
manufacturing methods, for example, the methods described in
Science, 2012, vol. 338, pp. 643 to 647.
[0192] Hereinafter, a method for manufacturing a photoelectric
conversion element and a solar cell of the present invention will
be briefly described.
[0193] The blocking layer 14, the porous layer 12, and at least one
of the electron transport layer 15 or the hole transport layer 16
is formed on the surface of the conductive support 11 as
desired.
[0194] The blocking layer 14 can be formed by, for example,
applying a dispersion including the above-described insulating
substance, a precursor compound thereof, or the like onto the
surface of the conductive support 11 and firing the dispersion or
thermally decomposing the dispersion by means of spraying.
[0195] A material used to form the porous layer 12 is preferably
used in a fine particle form and more preferably used in a form of
fine particles in a dispersion.
[0196] A method for forming the porous layer 12 is not particularly
limited, and examples thereof include wet-type methods, dry-type
methods, and other methods (for example, methods described in
Chemical Review, Vol. 110, p. 6595 (published on 2010)). In these
methods, it is preferable to apply the dispersion (paste) onto the
surface of the conductive support 11 or the surface of the blocking
layer 14 and then fire the dispersion at a temperature 100.degree.
C. to 800.degree. C. for ten minutes to ten hours. In such a case,
it is possible to bring the fine particles into close contact with
each other.
[0197] In a case in which firing is performed multiple times, the
temperature of firing that is not the final firing (the non-final
firing temperature) is preferably set to be lower than the
temperature of the final firing (the final firing temperature). For
example, in a case in which titanium oxide paste is used, the
non-final firing temperature can be set in a range of 50.degree. C.
to 300.degree. C. In addition, the final firing temperature can be
set to be higher than the non-firing firing temperature in a range
of 100.degree. C. to 600.degree. C. In a case in which a glass
support is used as the support 11a, the firing temperature is
preferably 60.degree. C. to 500.degree. C.
[0198] The amount of a porous material applied to form the porous
layer 12 is appropriately set depending on the film thickness of
the porous layer 12, the number of times of coating, and the like
and is not particularly limited. The amount of the porous material
applied to square meter of the surface area of the conductive
support 11 is, for example, preferably 0.5 to 500 g and more
preferably 5 to 100 g.
[0199] In a case in which the electron transport layer 15 or the
hole transport layer 16 is provided, the layer can be formed in the
same manner as the hole transport layer 3 or the electron transport
layer 4 described below.
[0200] Next, the photosensitive layer 13 is provided.
[0201] A method for providing the photosensitive layer 13 is not
particularly limited, and examples thereof include wet-type methods
and dry-type methods. In the present invention, wet-type methods
are preferred, and, for example, a method in which the surface is
brought into contact with a light absorber solution including the
absorber is preferred. In this method, first, the light absorber
solution for forming the photosensitive layer 13 is prepared. The
light absorber solution includes MX.sub.2 and AX which are raw
materials of the perovskite compound. Here, A, M, and X are the
same as A, M, and X in Formula (I). In this light absorber
solution, the molar ratio between MX.sub.2 and AX is appropriately
adjusted depending on the purpose. In a case in which a perovskite
compound is formed as the light absorber, the molar ratio between
MX.sub.2 and AX is preferably 1:1 to 10:1. The light absorber
solution can be prepared by mixing AX and MX.sub.2 in a
predetermined molar ratio and then, preferably, heating the
components. This forming liquid is generally a solution, but may be
a suspension. Heating conditions are not particularly limited, but
the heating temperature is preferably 30.degree. C. to 200.degree.
C. and more preferably 60.degree. C. to 150.degree. C. The heating
duration is preferably 0.5 to 100 hours and more preferably 1 to 3
hours. As a solvent or a dispersion medium, substances described
below can be used.
[0202] Next, the prepared light absorber solution is brought into
contact with the surface of a layer forming the photosensitive
layer 13 on the surface thereof (in the photoelectric conversion
element 10, any layer of the porous layer 12, the blocking layer
14, the electron transport layer 15, or the hole transport layer
16). Specifically, it is preferable to apply the light absorber
solution onto the surface or immerse the surface in the forming
liquid. Therefore, a perovskite compound is formed on the surface
of the porous layer 12, the blocking layer 14, the electron
transport layer 15, or the hole transport layer 16. The temperature
at which the forming liquid is brought into contact with the
surface is preferably 5.degree. C. to 100.degree. C., and the
immersion duration is preferably 5 seconds to 24 hours and more
preferably 20 seconds to 1 hour. In a case in which the applied
light absorber solution is dried, the forming liquid is preferably
dried using heat and is generally dried by being generally heated
at 20.degree. C. to 300.degree. C. and being preferably heated at
50.degree. C. to 170.degree. C.
[0203] In addition, it is also possible to for the photosensitive
layer according to a method for synthesizing the above-described
perovskite compound.
[0204] Furthermore, examples thereof also include a method in which
an AX solution including the AX and an MX.sub.2 solution including
the MX.sub.2 are separately applied (including the immersion
method) and are dried as necessary. In this method, any solution
may be applied in advance, but the MX.sub.2 solution is preferably
applied in advance. In this method, the molar ratio between AX and
MX.sub.2, coating conditions, and drying conditions are the same as
those in the above-described method. In this method, instead of
applying the AX solution and the MX.sub.2 solution, it is also
possible to vapor-deposit AX or MX.sub.2.
[0205] Furthermore, as another method, it is possible to use a
dry-type method such as vapor deposition in a vacuum in which a
compound or a mixture obtained by removing the solvent from the
light absorber solution is used. For example, it is possible to use
a method in which the AX and the MX.sub.2 are simultaneously or
sequentially vapor-deposited.
[0206] Therefore, the light absorber is formed and turns into the
photosensitive layer 13.
[0207] On the photosensitive layer 13 provided as described above,
preferably, the hole transport layer 3 or the electron transport
layer 4 is formed.
[0208] The hole transport layer 3 can be formed by applying and
drying a hole-transporting material solution including a
hole-transporting material. In the hole-transporting material
solution, the concentration of the hole-transporting material is
preferably 0.01 to 1.0 M (mol/L) since coatability is excellent
and, in a case in which the porous layer 12 is provided and pores
are present, the hole-transporting material is capable of easily
intruding into the inside of pores in the porous layer 12.
[0209] The electron transport layer 4 can be formed by applying and
drying an electron-transporting material solution including an
electron-transporting material.
[0210] After the hole transport layer 3 or the electron transport
layer 4 is formed, the second electrode 2 is formed, thereby
manufacturing the photoelectric conversion element and the solar
cell.
[0211] The film thicknesses of the respective layers can be
adjusted by appropriately changing the concentrations of the
respective dispersion liquids or solutions and the number of times
of coating. For example, in a case in which the photosensitive
layers 13B and 13C having a thick film thickness are provided, the
light absorber solution may be applied and dried multiple
times.
[0212] The respective dispersion liquids and solutions described
above may respectively include additives such as a dispersion aid
and a surfactant.
[0213] Examples of the solvent or dispersion medium that is used in
the method for manufacturing the photoelectric conversion element
and the solar cell include solvents described in JP2001-291534A,
but the solvent or dispersion medium is not limited thereto. In the
present invention, organic solvents are preferred, and alcohol
solvents, amide solvents, nitrile solvents, hydrocarbon solvents,
lactone solvents, halogen solvents, sulfide solvents, and solvent
mixtures of two or more thereof are preferred. The solvent mixture
is preferably a solvent mixture of an alcohol solvent and a solvent
selected from amide solvents, nitrile solvents, and hydrocarbon
solvents. Specifically, methanol, ethanol, isopropanol,
.gamma.-butyrolactone, chlorobenzene, acetonitrile,
dimethylformamide (DMF) or dimethylacetamide, or a solvent mixture
thereof is preferred.
[0214] A method for applying the solutions or dispersants used to
form the respective layers is not particularly limited, and it is
possible to use a well-known coating method such as spin coating,
extrusion die coating, blade coating, bar coating, screen printing,
stencil printing, roll coating, curtain coating, spray coating, dip
coating, an inkjet printing method, or an immersion method. Among
these, spin coating, screen printing, an immersion method, and the
like are preferred.
[0215] The photoelectric conversion element produced as described
above can be used as a solar cell by connecting the external
circuit 6 to the first electrode 1 and the second electrode 2.
[0216] Composition
[0217] A composition of the present invention includes a compound
represented by Formula (1a) and a halogenated metal.
R.sup.1.sub.3Si-L-NR.sup.2.sub.3Hal Formula (1a)
[0218] In the formula, R.sup.1, R.sup.2, and L are the same as
R.sup.1, R.sup.2, and L in Formula (1) respectively, and preferred
aspects thereof are also identical. Hal represents a halogen atom
(preferably an iodine atom, a chlorine atom, or a bromine
atom).
[0219] The composition of the present invention may include one or
more compounds represented by Formula (1a).
[0220] Examples of the halogenated metal included in the
composition of the present invention include halides of the
above-described metallic atoms M other than elements belonging to
Group I of the periodic table which the perovskite compound being
used in the present invention has (that is, compounds represented
by M(Hal).sub.2; Hal represents a halogen atom), at least one
selected from halides of Pb and halides of Sn is more preferred, at
least one selected from iodides or chlorides of Pb and iodides or
chlorides of Sn is still more preferred, and at least one selected
from PbI.sub.2 and SnI.sub.2 is particularly preferred.
[0221] The composition of the present invention may be a solid
(powder, granule, or the like) or a solution. In a case in which
the composition of the present invention is a solution, an organic
solvent is preferably used as the medium. The organic solvent is
not particularly limited, and examples thereof include alcohol
solvents, amide solvents, nitrile solvents, hydrocarbon solvents,
lactone solvents, halogen solvents, and solvent mixtures of two or
more solvents described above. The organic solvent that the
composition of the present invention may have is more preferably
methanol, ethanol, isopropanol, .gamma.-butyrolactone,
chlorobenzene, acetonitrile, DMF, dimethylacetamide, dimethyl
sulfoxide, or a solvent mixture thereof.
[0222] The composition of the present invention may further have
additional components other than the compound represented by
Formula (1a) and the halogenated metal. As the additional
components, the composition of the present invention preferably
includes at least one compound represented by R.sup.A--NH.sub.3Hal
(R.sup.A is the same as R.sup.A in Formula (2), and a preferred
aspect thereof is also identical; Hal represents a halogen atom and
is preferably an iodine atom, a chlorine atom, or a bromine atom).
R.sup.A--NH.sub.3Hal is more preferably CH.sub.3NH.sub.3Hal or
CH.sub.3CH.sub.2NH.sub.3Hal.
[0223] In the composition of the present invention, the molar ratio
of the content a of the compound represented by Formula (Ia) to the
content b of the halogenated metal is preferably
0.001.ltoreq.a/b.ltoreq.10, more preferably
0.01.ltoreq.a/b.ltoreq.10, and still more preferably
0.01.ltoreq.a/b.ltoreq.3.
[0224] In addition, in a case in which the composition of the
present invention includes R.sup.A--NH.sub.3Hal, in the composition
of the present invention, the molar ratio of the content c of
R.sup.A--NH.sub.3Hal to the content a of the compound represented
by Formula (1a) is preferably 4.ltoreq.c/a.ltoreq.999, more
preferably 19.ltoreq.c/a.ltoreq.499, and particularly preferably
49.ltoreq.c/a.ltoreq.199.
[0225] In addition, in a case in which the composition of the
present invention includes the compound represented by Formula (Ia)
and R.sup.A--NH.sub.3Hal, in the composition of the present
invention, the molar ratio of the total of the content a of the
compound represented by Formula (1a) and the content c of
R.sup.A--NH.sub.3Hal to the content b of the halogenated metal is
preferably 1.ltoreq.(a+c)/b.ltoreq.10 and more preferably
1.ltoreq.(a+c)/b.ltoreq.5.
[0226] In addition, the composition of the present invention may
also include a halide of an element belonging to Group I of the
periodic table as the additional component.
[0227] The composition of the present invention can be preferably
used as supply sources of MX.sub.2 and AX described above in the
formation of the photosensitive layer of the photoelectric
conversion element of the present invention. In a case in which the
composition of the present invention is powder, granules, or the
like, the composition of the present invention can be used as the
above-described light absorber solution after being dissolved in a
solvent so as to prepare a solution having an appropriate
concentration and carrying out filtration, purification, and the
like as necessary. In addition, in a case in which the composition
of the present invention is a solution, the composition can be used
as the above-described light absorber solution as it is or after
being condensed, diluted, filtered, purified, or the like.
[0228] That is, the composition of the present invention can be
preferably used to form the photosensitive layer in the
manufacturing of the photoelectric conversion element of the
present invention.
[0229] Hereinafter, the present invention will be described in more
detail on the basis of examples, but the present invention is not
limited thereto.
EXAMPLES
Example and Comparative Example
[0230] [Manufacturing of Photoelectric Conversion Element (Specimen
No. 101)]
[0231] The photoelectric conversion element 10A illustrated in FIG.
1 was manufactured in an order described below. Meanwhile, in a
case in which the film thickness of the photosensitive layer 13 is
large, the photoelectric conversion element corresponds to the
photoelectric conversion element 10B illustrated in FIG. 2.
[0232] <Production of Conductive Support 11>
[0233] A fluorine-doped SnO.sub.2 conductive film (the transparent
electrode 11b) was formed on a glass substrate (the support 11a,
thickness: 2.2 mm), thereby producing a conductive support 11.
[0234] <Preparation of Solution for Blocking Layer>
[0235] An isopropanol solution containing 15% by mass of titanium
diisopropoxide bis(acetylacetonate) (manufactured by Sigma-Aldrich
Japan K.K.) was diluted with 1-butanol, thereby preparing 0.02 M of
a solution for a blocking layer.
[0236] <Formation of Blocking Layer 14>
[0237] A blocking layer 14 made of titanium oxide (having a film
thickness of 50 nm) was formed on the SnO.sub.2 conductive film of
the conductive support 11 using 0.02 M of the solution for the
blocking layer at 450.degree. C. by means of a spray thermal
decomposition method.
[0238] <Preparation of Titanium Oxide Paste>
[0239] Ethyl cellulose, lauric acid, and terpineol were added to an
ethanol dispersion liquid of titanium oxide (anatase, an average
particle diameter of 20 nm), thereby preparing titanium oxide
paste.
[0240] <Formation of Porous Layer 12>
[0241] The prepared titanium oxide paste was applied onto the
blocking layer 14 by means of a screen printing method and was
fired. The application and firing of the titanium oxide paste were
repeated again. Meanwhile, the first firing was carried out at
130.degree. C. for one hour, and the second firing was carried out
at 500.degree. C. for one hour. The obtained titanium oxide fired
body was immersed in an aqueous solution of 40 mM of TiCl.sub.4,
then, was heated at 60.degree. C. for one hour, and, continuously,
was heated at 500.degree. C. for 30 minutes, thereby forming the
porous layer 12 (having a film thickness of 250 nm) made of
TiO.sub.2.
[0242] <Formation of Photosensitive Layer 13A>
[0243] (Synthesis of CH.sub.3NH.sub.3I)
[0244] A 40% methanol solution of methyl amine (27.86 mL) and an
aqueous solution of 57% by mass of hydrogen iodide (hydroiodic
acid, 30 mL) were stirred in a flask at 0.degree. C. for two hours
and then condensed, thereby obtaining a CH.sub.3NH.sub.3I coarse
body. The obtained CH.sub.3NH.sub.3I coarse body was dissolved in
ethanol and was recrystallized with diethyl ether. The precipitated
crystals were filtered and were dried at 60.degree. C. for 24 hours
under reduced pressure, thereby obtaining purified
CH.sub.3NH.sub.3I.
[0245] (Synthesis of Compound (a1))
[0246] Compound (a1) was synthesized as illustrated in the
following synthesis scheme.
##STR00008##
[0247] (Synthesis of Compound (a2))
[0248] A 10% ethanol solution of Compound (a1) synthesized above
(117 g) and an aqueous solution of 57% by mass of hydrogen iodide
(23 g) were stirred in a flask at 0.degree. C. for two hours, then,
the solvent was removed by means of condensation, and then the
components were further dried at 60.degree. C. for 24 hours under
reduced pressure, thereby obtaining Compound (a2).
[0249] (Preparation of Light Absorber Solution A)
[0250] Next, the molar ratios among the purified CH.sub.3NH.sub.3I,
Compound (a2), and PbI.sub.2 were set to 99.8:0.2:50, and the
components were stirred and mixed together at 60.degree. C. in
dimethylformamide (DMF) for 12 hours, and then filtered using a
polytetrafluoroethylene (PTFE) syringe filter, thereby preparing
40% by mass of a light absorber solution A.
[0251] The prepared light absorber solution A was applied onto the
porous layer 12 using a spin coating method (at 2,000 rpm for 60
seconds), and the light absorber solution A was dried at
100.degree. C. for 90 minutes using a hot plate, thereby forming a
photosensitive layer A (having a film thickness of 300 nm
(including the film thickness of the porous layer 12 of 250 nm)) as
the photosensitive layer 13A having a perovskite compound.
[0252] A first electrode 1 was produced in the above-described
manner.
[0253] <Preparation of Hole-Transporting Material
Solution>
[0254] Spiro-OMeTAD (180 mg) as a hole-transporting material was
dissolved in chlorobenzene (1 mL). An acetonitrile solution (37.5
.mu.L) obtained by dissolving
lithium-bis(trifluoromethanesulfonyl)imide (170 mg) in acetonitrile
(1 mL) and t-butylpyridine (TBP, 17.5 .mu.L) were added to and
mixed with the chlorobenzene solution, thereby preparing a
hole-transporting material solution.
[0255] <Formation of Hole Transport Layer 3>
[0256] Next, the hole-transporting material solution was applied
onto the photosensitive layer 13 in the first electrode 1 using a
spin coating, and the applied hole-transporting material solution
was dried, thereby forming a hole transport layer 3 (film
thickness: 0.1 .mu.m).
[0257] <Production of Second Electrode 2>
[0258] Gold (film thickness: 0.1 .mu.m) was vapor-deposited on the
hole transport layer 3 using a vapor deposition method, thereby
producing a second electrode 2.
[0259] A photoelectric conversion element 10 with Specimen No. 101
was manufactured in the above-described manner.
[0260] [Manufacturing of Photoelectric Conversion Elements
(Specimen Nos. 102 to 104)]
[0261] Photoelectric conversion elements 10 with Specimen Nos. 102
to 104 were manufactured in the same manner as in the manufacturing
of the photoelectric conversion element with Specimen No. 101
except for the fact that, in the <formation of photosensitive
layer 13A> during the manufacturing of the above-described
photoelectric conversion element with Specimen No. 101, the mixing
molar ratio between the purified CH.sub.3NH.sub.3I and Compound
(a2) was changed as shown in the table below. Meanwhile, the mixing
molar ratio between the total amount of the purified
CH.sub.3NH.sub.3I and Compound (a2) and PbI.sub.2 was set, similar
to that in the manufacturing with Specimen No. 101, to 2:1.
[0262] [Manufacturing of Photoelectric Conversion Element (Specimen
No. 105)]
[0263] A photoelectric conversion element 10 with Specimen No. 105
was manufactured in the same manner as in the manufacturing of the
photoelectric conversion element with Specimen No. 101 except for
the fact that, in the <formation of photosensitive layer 13A>
during the manufacturing of the above-described photoelectric
conversion element with Specimen No. 101, methylamine was changed
to ethylamine, and the molar ratios among the purified
CH.sub.3CH.sub.2NH.sub.3I, Compound (a2), and PbI.sub.2 were set to
98:2:50.
[0264] [Manufacturing of Photoelectric Conversion Elements
(Specimen Nos. 106 to 133)]
[0265] Photoelectric conversion elements 10 with Specimen Nos. 106
to 133 were manufactured in the same manner as in the manufacturing
of the photoelectric conversion element with Specimen No. 101
except for the fact that, in the <formation of photosensitive
layer 13A> during the manufacturing of the above-described
photoelectric conversion element with Specimen No. 101, Compound
(b1), (g1), (s1), (w1), (x1), (y1), (z1), (aa1), (bb1), (cc1), or
(dd1) was used instead of Compound (a1), each of Compound (b2),
(g2), (s2), (w2), (x2), (y2), (z2), (aa2), (bb2), (cc2), or (dd2)
was obtained, and the mixing molar ratio between each of these
compounds and the purified CH.sub.3NH.sub.3I was changed as shown
in the table below. Meanwhile, the mixing molar ratio between the
total amount of the purified CH.sub.3NH.sub.3I and Compound (b2),
(g2), (s2), (w2), (x2), (y2), (z2), (aa2), (bb2), (cc2), or (dd2)
and PbI.sub.2 was set, similar to that in the manufacturing of
Specimen No. 101, to 2:1.
##STR00009## ##STR00010## ##STR00011##
[0266] [Manufacturing of Photoelectric Conversion Element (Specimen
No. 201)]
[0267] A photoelectric conversion element 10 with Specimen No. 201
was manufactured in the same manner as in the manufacturing of the
photoelectric conversion element with Specimen No. 101 except for
the fact that, in the <formation of photosensitive layer
13A>during the manufacturing of the above-described
photoelectric conversion element with Specimen No. 101, the
following process was carried out.
[0268] A 40% methanol solution of methyl amine (27.86 mL) and an
aqueous solution of 57% by mass of hydrogen iodide (hydroiodic
acid, 30 mL) were stirred in a flask at 0.degree. C. for two hours
and then condensed, thereby obtaining a CH.sub.3NH.sub.3I coarse
body. The obtained CH.sub.3NH.sub.3I coarse body was dissolved in
ethanol and was recrystallized with diethyl ether. The precipitated
crystals were filtered and were dried at 60.degree. C. for 24 hours
under reduced pressure, thereby obtaining purified
CH.sub.3NH.sub.3I.
[0269] Next, the molar ratio between the purified CH.sub.3NH.sub.3I
and PbI.sub.2 was set to 2:1, the components were stirred and mixed
together at 60.degree. C. in .gamma.-butyrolactone for 12 hours and
then filtered using a polytetrafluoroethylene (PTFE) syringe
filter, thereby preparing 40% by mass of a light absorber solution
B.
[0270] The prepared light absorber solution B was applied onto the
porous layer 12 using a spin coating method (at 2,000 rpm for 60
seconds and subsequently at 3,000 rpm for 60 seconds), and the
applied light absorber solution B was dried at 100.degree. C. for
40 minutes using a hot plate, thereby forming a photosensitive
layer A (having a film thickness of 600 nm (including the film
thickness of the porous layer 12 of 500 nm)) as the photosensitive
layer 13A having a perovskite compound.
[0271] [Manufacturing of Photoelectric Conversion Element (Specimen
No. 202)]
[0272] A photoelectric conversion element 10 with Specimen No. 202
was manufactured in the same manner as in the manufacturing of the
photoelectric conversion element with Specimen No. 201 except for
the fact that, in the <formation of photosensitive layer 13A>
during the manufacturing of the above-described photoelectric
conversion element with Specimen No. 201, methylamine was changed
to a mixture of methylamine and ethylamine (the molar ratio of
methylamine to ethylamine was set to 9), and the molar ratios among
CH.sub.3NH.sub.3I:CH.sub.3CH.sub.2NH.sub.3I:PbI.sub.2 were set to
1.8:0.2:1 in the case of the preparation of the light absorber
solution B.
[0273] [Evaluation of Moisture Resistance]
[0274] <Measurement of Initial Photoelectric Conversion
Efficiency>
[0275] Photoelectric conversion efficiencies were evaluated in the
following manner.
[0276] Three testing pieces of the photoelectric conversion element
with each specimen number were manufactured. Cell characteristics
testing was carried out on the three testing pieces respectively,
and photoelectric conversion efficiencies (.eta.%) were measured.
In addition, the average value of the values of these three testing
pieces was considered as the initial photoelectric conversion
efficiency (.eta.%) of the photoelectric conversion element with
each specimen number. The cell characteristics testing was carried
out by radiating 1,000 W/m.sup.2 of quasi-sunlight from a xenon
lamp through an AM1.5 filter using a solar simulator "WXS-85H"
(Wacom). Current-voltage characteristics were measured using an I-V
tester, and photoelectric conversion efficiencies (.eta.%) were
obtained.
[0277] <Evaluation of Moisture Resistance>
[0278] The moisture resistance of the photoelectric conversion
element was measured in the following manner.
[0279] Three testing pieces of each specimen number were stored in
a constant temperature and humidity tank with a temperature of
25.degree. C. and a humidity of 60% RH for 24 hours respectively,
cell characteristics testing was carried out in the same manner as
described above, and photoelectric conversion efficiencies (.eta.%)
were measured. The average value of the values of the three testing
pieces was considered as the photoelectric conversion efficiency
(.eta.%) of the photoelectric conversion element with each specimen
number after the storage.
[0280] The moisture resistance of the photoelectric conversion
element was evaluated from the decline percentage of the
photoelectric conversion efficiency computed using the following
expression according to the following evaluation standards.
Decline percentage (%)=100-{100.times.(photoelectric conversion
efficiency after storage)/(initial photoelectric conversion
efficiency)}
[0281] --Moisture Resistance Evaluation Standards--
[0282] A: The decline percentage is less than 25%
[0283] B: The decline percentage is 25% or more and less than
29%
[0284] C: The decline percentage is 29% or more and less than
33%
[0285] D: The decline percentage is 33% or more and less than
37%
[0286] E: The decline percentage is 37% or more
[0287] In the moisture resistance evaluation standards, [A], [B],
[C], and [D] are pass levels, [A], [B], and [C] are preferred, and
[A] is more preferred. On the other hand, at [E] level, the decline
percentage is large, and the moisture resistance fails to reach the
pass level (required level) of the present invention.
[0288] The results are shown in Table 1.
[0289] Meanwhile, [A2]/[A1] shown in Table 1 corresponds to the
molar ratio of the organic cations not having a silyl group to the
organic cations having a silyl group which constitute the
perovskite compound.
TABLE-US-00001 TABLE 1 Specimen R.sup.A-NH.sub.3I
R.sup.1.sub.3Si-L-NR.sup.2.sub.3I Molar ratio Moisture No. [A2]
[A1] [A2]/[A1] resistance 101 CH.sub.3NH.sub.3I (a2) 499 B Present
Invention 102 CH.sub.3NH.sub.3I (a2) 199 A Present Invention 103
CH.sub.3NH.sub.3I (a2) 49 A Present Invention 104 CH.sub.3NH.sub.3I
(a2) 19 B Present Invention 105 CH.sub.3CH.sub.2NH.sub.3I (a2) 49 A
Present Invention 106 CH.sub.3NH.sub.3I (b2) 49 B Present Invention
107 CH.sub.3NH.sub.3I (b2) 199 B Present Invention 108
CH.sub.3NH.sub.3I (b2) 499 C Present Invention 109
CH.sub.3NH.sub.3I (w2) 49 A Present Invention 110 CH.sub.3NH.sub.3I
(w2) 199 A Present Invention 111 CH.sub.3NH.sub.3I (w2) 499 B
Present Invention 112 CH.sub.3NH.sub.3I (x2) 49 A Present Invention
113 CH.sub.3NH.sub.3I (x2) 199 A Present Invention 114
CH.sub.3NH.sub.3I (x2) 499 B Present Invention 115
CH.sub.3NH.sub.3I (y2) 49 A Present Invention 116 CH.sub.3NH.sub.3I
(y2) 199 A Present Invention 117 CH.sub.3NH.sub.3I (y2) 499 B
Present Invention 118 CH.sub.3NH.sub.3I (z2) 49 A Present Invention
119 CH.sub.3NH.sub.3I (z2) 199 A Present Invention 120
CH.sub.3NH.sub.3I (z2) 499 B Present Invention 121
CH.sub.3NH.sub.3I (aa2) 499 B Present Invention 122 None (w2) 0 D
Present Invention 123 CH.sub.3NH.sub.3I (w2) 0.67 D Present
Invention 124 CH.sub.3NH.sub.3I (w2) 9 C Present Invention 125
CH.sub.3NH.sub.3I (w2) 24 B Present Invention 126 CH.sub.3NH.sub.3I
(w2) 99 A Present Invention 127 CH.sub.3NH.sub.3I (w2) 249 B
Present Invention 128 CH.sub.3NH.sub.3I (w2) 999 C Present
Invention 129 CH.sub.3NH.sub.3I (g2) 49 B Present Invention 130
CH.sub.3NH.sub.3I (s2) 49 A Present Invention 131 CH.sub.3NH.sub.3I
(bb2) 49 A Present Invention 132 CH.sub.3NH.sub.3I (cc2) 49 A
Present Invention 133 CH.sub.3NH.sub.3I (dd2) 49 A Present
Invention 201 CH.sub.3NH.sub.3I None -- E Comparative Example 202
CH.sub.3NH.sub.3I None -- E Comparative CH.sub.3CH.sub.2NH.sub.3I
Example
[0290] As shown in Table 1, in a case in which the perovskite
compound in the light absorber did not include the organic cations
having a silyl group in the crystal structure, it was turned out
that the photoelectric conversion efficiency of the photoelectric
conversion element significantly decreased under high-humidity
conditions.
[0291] In contrast, in a case in which the perovskite compound in
the light absorber included the organic cations having a silyl
group in the crystal structure, it was found that the photoelectric
conversion efficiency of the photoelectric conversion element did
not easily decrease even under high-humidity conditions and the
moisture resistance was excellent.
[0292] From the above-described results, it is found that the
photoelectric conversion element or the solar cell of the present
invention exhibit excellent moisture resistance.
[0293] The present invention has been described together with
embodiments thereof and drawings, but the present inventors do not
limit the present invention in any detailed part of the description
unless particularly otherwise described and consider that the
present invention is supposed to be widely interpreted within the
scope of the concept of the present invention which is described in
the accompanying claims.
Explanation of References
[0294] 1A, 1B, 1C, 1D, 1E: first electrode [0295] 11: conductive
support [0296] 11a: support [0297] 11b: transparent electrode
[0298] 12: porous layer [0299] 13A, 13B, 13C: photosensitive layer
[0300] 14: blocking layer [0301] 15: electron transport layer
[0302] 16: hole transport layer [0303] 2: second electrode [0304]
3A, 3B: hole transport layer [0305] 4: electron transport layer
[0306] 6: external circuit (lead) [0307] 10A, 10B, 10C, 10D, 10E:
photoelectric conversion element [0308] 100A, 100B, 100C, 100D,
100E: system in which photoelectric conversion element is applied
as cell [0309] M: electric motor
* * * * *