U.S. patent application number 17/299698 was filed with the patent office on 2022-02-17 for self-assembled monolayer for electrode modification and device comprising such self-assembled monolayer.
The applicant listed for this patent is Merck Patent GmbH. Invention is credited to William MITCHELL, David SPARROWE, Changsheng WANG.
Application Number | 20220052277 17/299698 |
Document ID | / |
Family ID | 1000005995690 |
Filed Date | 2022-02-17 |
United States Patent
Application |
20220052277 |
Kind Code |
A1 |
SPARROWE; David ; et
al. |
February 17, 2022 |
SELF-ASSEMBLED MONOLAYER FOR ELECTRODE MODIFICATION AND DEVICE
COMPRISING SUCH SELF-ASSEMBLED MONOLAYER
Abstract
The present application relates to a self-assembled monolayer
suitable for the modification of electrodes comprised in electronic
devices as well as to such electronic devices. The present
application also relates to a method for depositing such
self-assembled monolayer onto an electrode as well as to the
manufacturing of the corresponding devices.
Inventors: |
SPARROWE; David;
(Bournemouth, GB) ; WANG; Changsheng; (Eastleigh,
GB) ; MITCHELL; William; (Chandler's Ford,
GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Merck Patent GmbH |
Darmstadt |
|
DE |
|
|
Family ID: |
1000005995690 |
Appl. No.: |
17/299698 |
Filed: |
November 14, 2019 |
PCT Filed: |
November 14, 2019 |
PCT NO: |
PCT/EP2019/081261 |
371 Date: |
June 3, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 51/102 20130101;
H01L 2251/308 20130101; H01L 51/0003 20130101; H01L 51/442
20130101; H01L 51/0094 20130101 |
International
Class: |
H01L 51/00 20060101
H01L051/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 4, 2018 |
EP |
18210015.6 |
Claims
1.-14. (canceled)
15. An organic electronic device comprising an electrode, a
self-assembled monolayer on said electrode and an organic
semiconducting layer on said self-assembled monolayer, wherein said
self-assembled monolayer is formed by depositing the reaction
product of a compound of the following formula (I
R.sup.1--SiX.sub.3 (I) and an alcohol of formula R.sup.2--OH onto
said electrode, with R.sup.1 being at each occurrence independently
alkyl having from 1 to 10 carbon atoms, said alkyl being
substituted with at least one electron-withdrawing group R.sup.A,
or aryl having from 6 to 30 aromatic carbon ring atoms, said aryl
being substituted with at least one electron-withdrawing group;
R.sup.2 being an alkyl group having from 1 to 10 carbon atoms; and
X being at each occurrence independently halogen or alkoxy having
from 1 to 10 carbon atoms.
16. The organic electronic device according to claim 15, wherein
the self-assembled monolayer is formed by depositing the
formulation comprising the compound of formula (I) and the alcohol
of formula R.sup.2--OH onto the electrode.
17. The organic electronic device according to claim 15, wherein
R.sup.1 is at each occurrence independently a group select of any
of the following formulae (II-a) or (II-b) ##STR00041## wherein b
is at each occurrence independently an integer of at least 1 and of
at most 10; c is at each occurrence an integer of at least 1 and at
most 2b+1; d is at each occurrence an integer of at least 0 and at
most 2b; with the provision that the sum of c and d is 2b+1; and e
is at each occurrence independently an integer of at least 1 and of
at most 5.
18. The organic electronic device according to claim 17, wherein c
is 2b+1.
19. The organic electronic device according to claim 17, wherein e
is 5.
20. The organic electronic device according to claim 15, wherein
R.sup.A is at each occurrence independently selected from the group
consisting of --NO.sub.2, --CN, --F, --Cl, --Br, --I, --OAr.sup.2,
--OR.sup.3, --COR.sup.3, --SH, --SR.sup.3, --OH,
--C.ident.CR.sup.3, --CH.dbd.CR.sup.3.sub.2, and alkyl having from
1 to 10 carbon atoms, wherein one or more, preferably all, hydrogen
atoms are replaced by F, with Ar.sup.2 being at each occurrence
independently an aryl having from 6 to 30 carbon atoms, and R.sup.3
being at each occurrence independently an alkyl having from 1 to 10
carbon atoms or an alkyl having from 1 to 10 carbon atoms wherein
one or more hydrogen atom is replaced by F.
21. The organic electronic device according to claim 15, wherein
R.sup.A is F.
22. The organic electronic device according to claim 15, wherein
the compound of formula (I) is selected from the group consisting
of the following formulae (I-1) to (I-11) ##STR00042## wherein e is
an integer of at least 1 and at most 10.
23. The organic electronic device according to claim 15, wherein
the electrode is an indium tin oxide electrode.
24. The organic electronic device according to claim 15, wherein
R.sup.2 is an alkyl having from 1 to 5 carbon atoms.
25. The organic electronic device according to claim 15, wherein
R.sup.2 is iso-propyl.
26. The organic electronic device according to claim 15, said
organic electronic device being selected from the group consisting
of organic field effect transistors (OFET), organic thin film
transistors (OTFT), organic light emitting diodes (OLED), organic
light emitting transistors (OLET), organic photovoltaic devices
(OPV), organic photodetectors (OPD), organic solar cells, laser
diodes, Schottky diodes, photoconductors and photodetectors.
27. The organic electronic device according to claim 15, said
organic electronic device being an organic field effect transistor
(PFET) or an organic thin film transistor (OTFT).
28. A method of producing the organic electronic device of claim
15, said method comprising the steps of (a) providing an electrode,
optionally on a substrate; (b) depositing onto said electrode a
formulation comprising a compound of formula (I) R.sup.1--SiX.sub.3
(I) and an alcohol of formula R.sup.2--OH, with R.sup.1 being at
each occurrence independently alkyl having from 1 to 10 carbon
atoms, said alkyl being substituted with at least one
electron-withdrawing group R.sup.A, or aryl having from 6 to 30
aromatic carbon ring atoms, said aryl being substituted with at
least one electron-withdrawing group R.sup.A; R.sup.2 being an
alkyl group having from 1 to 10 carbon atoms; and X being at each
occurrence independently halogen or alkoxy having from 1 to 10
carbon atoms, to obtain a self-assembled monolayer; and (c)
depositing onto said self-assembled monolayer an organic
semiconducting material to obtain an organic semiconducting
layer.
29. The method according to claim 28, wherein R.sup.1 is at each
occurrence independently a group select of any of the following
formulae (II-a) or (II-b) ##STR00043## wherein b is at each
occurrence independently an integer of at least 1 and of at most
10; c is at each occurrence an integer of at least 1 and at most
2b+1; d is at each occurrence an integer of at least 0 and at most
2b; with the provision that the sum of c and d is 2b+1; and e is at
each occurrence independently an integer of at least 1 and of at
most 5; wherein R.sup.2 in the alcohol R.sup.2--OH is an alkyl
having from 1 to 5 carbon atoms; and the electrode is an indium tin
oxide electrode.
Description
TECHNICAL FIELD
[0001] The present application relates to a self-assembled
monolayer suitable for the modification of electrodes comprised in
electronic devices as well as to such electronic devices. The
present application also relates to a method for depositing such
self-assembled monolayer onto an electrode as well as to the
manufacturing of the corresponding devices.
BACKGROUND
[0002] Organic electronic materials have established their presence
in a wide range of electronic devices, such as organic
photodetectors (OPD), organic photovoltaic cells (OPV), organic
light emitting diodes (OLEDs) and organic field effect transistors
(OFETs), to name a few only. Because they may be deposited onto an
underlying substrate by solution processing, organic materials hold
the promise of allowing for simplified and highly flexible
production, potentially also leading to reduced manufacturing
costs.
[0003] In order to obtain an efficient organic electronic device,
the work function of the electrode materials has to match the
energy level of the highest occupied molecular orbital (HOMO) for a
p-type organic semiconducting material and of the lowest unoccupied
molecular orbital (LUMO) for an n-type organic semiconducting
material. Therefore, for a p-type organic electronic device gold,
palladium and platinum are suitable electrode materials.
Alternatively, silver electrodes have been used in combination with
self-assembled monolayers, wherein the self-assembled monolayer
brings the work function of the electrode to a level suitable for a
p-type organic electronic device.
[0004] An overview of the work function of the chemical elements is
given in Herbert B. Michaelson, Journal of Applied Physics 48, 4729
(1977); doi: 10.1063/1.323539. However, on the downside noble metal
electrodes add significant cost to the organic electronic device
and there is therefore an interest in using lower cost metals as
electrode materials.
[0005] Copper may, for example, be considered as a potential
alternative electrode material because of its good conductivity,
relatively low cost and relative ease to use in manufacturing
processes. In addition, copper is already widely used in the
semiconductor industry.
[0006] However, copper is chemically quite reactive and also
requires surface modification in order to match the work function
of the copper electrode to the respective organic semiconducting
material. Such surface modification may, for example, be done by
plating the copper surface with silver. Unfortunately, this
frequently leads to the formation of silver dendrites, consequently
rendering the so-produced electronic devices less efficient or even
completely useless.
[0007] As alternative electrode material molybdenum may also be
used, for example, in combination with a self-assembled monolayer
thereon formed by the deposition of octadecyltrichlorosilane and
phenethyltrichlorosilane, as disclosed by Dong-Jin Yun and Shi-Woo
Rhee in Journal of the Electrochemical Society 155(6) H357-H362
(2008).
[0008] Frequently, in organic electronic devices metal oxide
electrodes, such as for example indium tin oxide (ITO) electrodes,
are used. While good results have been achieved, it seems that
these electrodes need to be further modified so as to render their
work function better suitable for a p-type organic electronic
device.
[0009] There is therefore a need in the industry to overcome the
drawbacks of these electrodes.
[0010] Hence, it is an object of the present application to provide
an electrode, which is suitable for use in an organic electronic
device, preferably at reduced cost.
[0011] It is also an object of the present application to provide
for an electrode, the work function of which can be adapted to the
respective organic semiconducting materials used in the organic
electronic device.
[0012] In addition, it is an object of the present application to
provide for a compound and/or a method whereby the work function of
a metal oxide electrode can be adapted to the requirements of a
p-type organic electronic device.
[0013] Further, it is an object to provide for an organic
electronic device having good, preferably improved, performance,
for example electronic performance.
[0014] Additionally, it is an object of the present application to
provide for a production process for such electrode and such
organic electronic device.
SUMMARY
[0015] The present inventors have now surprisingly found that the
above objects may be attained either individually or in any
combination by the organic electronic device and its production
method as disclosed herein.
[0016] The present application therefore provides for an organic
electronic device comprising an electrode, a self-assembled
monolayer on said electrode and an organic semiconducting layer on
said self-assembled monolayer, wherein said self-assembled
monolayer is formed by depositing the reaction product of a
compound of the following formula (I)
R.sup.1--SiX.sub.3 (I)
and an alcohol of formula R.sup.2--OH onto said electrode, with
[0017] R.sup.1 being at each occurrence independently alkyl having
from 1 to 10 carbon atoms, said alkyl being substituted with at
least one electron-withdrawing group R.sup.A, or aryl having from 6
to 30 aromatic carbon ring atoms, said aryl being substituted with
at least one electron-withdrawing group; [0018] R.sup.2 being an
alkyl group having from 1 to 10 carbon atoms; and [0019] X being at
each occurrence independently halogen or alkoxy having from 1 to 10
carbon atoms.
[0020] Further, the present application also provides for a method
of producing the organic electronic device of any one or more of
claims 1 to 12, said method comprising the steps of [0021] (a)
providing an electrode, optionally on a substrate; [0022] (b)
depositing onto said electrode a formulation comprising a compound
of formula (I)
[0022] R.sup.1--SiX.sub.3 (I) [0023] and an alcohol of formula
R.sup.2--OH, [0024] with [0025] R.sup.1 being at each occurrence
independently alkyl having from 1 to 10 carbon atoms, said alkyl
being substituted with at least one electron-withdrawing group
R.sup.A, or aryl having from 6 to 30 aromatic carbon ring atoms,
said aryl being substituted with at least one electron-withdrawing
group R.sup.A; [0026] R.sup.2 being an alkyl group having from 1 to
10 carbon atoms; and [0027] X being at each occurrence
independently halogen or alkoxy having from 1 to 10 carbon atoms,
[0028] to obtain a self-assembled monolayer; and [0029] (c)
depositing onto said self-assembled monolayer an organic
semiconducting material to obtain an organic semiconducting
layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 shows a schematic representation of an exemplary top
gate OFET in accordance with the present application.
[0031] FIG. 2 shows a schematic representation of an exemplary
bottom gate OFET in accordance with the present application.
DETAILED DESCRIPTION OF THE INVENTION
[0032] As used herein, the term "organic electronic device" refers
to an electronic device comprising an organic semiconducting layer,
i.e. a semiconducting layer comprising at least 50 wt % (e.g. 60 wt
% or 70 wt % or 80 wt % or 90 wt % or 95 wt % or 97 wt % or 99.0 wt
% or 99.5 wt % or 99.7 wt % or 99.9 wt %), with wt % relative to
the total weight of said semiconducting layer, and preferably
consists of one or more organic semiconducting material.
[0033] As used herein, the terms "consist of" and "consisting of"
do not exclude the presence of impurities, which may normally be
present, for example but in no way limited to, impurities resulting
from the synthesis of a compound (e.g. an organic semiconducting
material) or--in case of metals--trace metals.
[0034] For the purposes of the present application, an asterisk "*"
is used to denote a linkage to an adjacent unit or group, including
for example, in case of a polymer, to an adjacent repeating unit or
any other group. In some instances, where specifically identified
as such, the asterisk "*" may also denote a mono-valent chemical
group.
[0035] In general terms the present application relates to an
organic electronic device. Said organic electronic device comprises
an electrode, a self-assembled monolayer and an organic
semiconducting layer, wherein the self-assembled monolayer is (or
is formed) on the electrode, and wherein the organic semiconducting
layer is on (or is deposited onto) the self-assembled monolayer.
Expressed differently, the organic electronic device comprises an
electrode, a self-assembled monolayer and an organic semiconducting
layer, with the self-assembled monolayer between the electrode and
the organic semiconducting layer.
[0036] The electrode comprises a metal or an electrically
conductive metal oxide or a blend thereof, preferably in at least
50 wt % (for example in at least 60 wt % or 70 wt % or 80 wt % or
90 wt % or 95 wt % or 97 wt % or 99.0 wt % or 99.5 wt % or 99.7 wt
% or 99 wt %), with wt % relative to the total weight of said
electrode, and most preferably consists of the metal or the
electrically conductive metal oxide or a blend thereof.
[0037] It is noted that the term "metal" as used herein also
includes the possibility of a blend of two or more metals. It is
also noted that the term "electrically conductive metal oxide" as
used herein also includes the possibility of a blend of two or more
metal oxides and/or the possibility of mixed metal oxides.
[0038] Said metal is not particularly limited. Metals generally
suitable may, for example, be selected from the group consisting of
chromium, molybdenum, tungsten, cobalt, rhodium, iridium, nickel,
palladium, platinum, gold, silver, and any blend of any of these,
with chromium, molybdenum and tungsten being preferred, and
molybdenum being most preferred.
[0039] Said metal oxide is not particularly limited, it is
nevertheless preferred that the electrically conductive metal oxide
is selected from the group consisting of indium tin oxide (ITO),
molybdenum oxide, tin oxide, and any blend of any of these.
[0040] The self-assembled monolayer essentially covers the
electrode. In this context the term "essentially covers" is used to
denote that--depending upon the architecture of the respective
organic electronic device--the self-assembled monolayer covers the
electrode in such a way that preferably no part of the electrode is
in direct physical contact with the organic semiconducting layer;
or that the self-assembled monolayer covers the entire surface of
the electrode, preferably the entire surface of the electrode
facing the organic semiconducting layer; or that the self-assembled
monolayer covers the part of the surface of the electrode that is
active in the change transfer.
[0041] The self-assembled monolayer is formed by depositing a
formulation comprising a compound of the following formula (I)
R.sup.1--SiX.sub.3 (I)
[0042] and an alcohol of formula R.sup.2--OH, with R.sup.1, R.sup.2
and X as defined herein, onto said electrode.
[0043] R.sup.2 is an alkyl group having from 1 to 10 carbon atoms.
Preferably, R.sup.2 is an alkyl group having from 1 to 5 carbon
atoms. Examples of such preferred groups R.sup.2 may be selected
from the group consisting of methyl, ethyl, n-propyl, iso-propyl,
n-butyl, iso-butyl, tert-butyl and n-pentyl. It is most preferred
that R.sup.2 is iso-propyl.
[0044] Without wishing to be bound by theory it is believed that
the compound of formula (I) reacts with the alcohol of formula
R.sup.2--OH to form compounds of the following formula (I-a) to
(I-c)
R.sup.1--SiX.sub.2(OR.sup.2) (I-a)
R.sup.1--SiX(OR.sup.2).sub.2 (I-b)
R.sup.1--Si(OR.sup.2).sub.3 (I-c)
[0045] of which formula (I-c) is, without wishing to be bound by
theory, considered the majority compound, possibly even the sole
compound.
[0046] Thus, consequently, without wishing to be bound by theory,
it is believed that the self-assembled monolayer may actually be
formed by depositing the reaction product of the compound of
formula (I) and the alcohol of formula R.sup.2--OH, for example by
depositing any one or more of compounds (I-a) to (I-c), preferably
of compound (I-c) predominantly or even solely.
[0047] X is at each occurrence independently halogen, preferably
Cl, or an alkoxy group having from 1 to 10 carbon atoms. Preferably
the alkoxy group is --O--C.sub.aH.sub.2a+1 with a being an integer
of at least 1 and of at most 10, preferably of at least 1 and of at
most 5. Examples of preferred alkoxy groups may be selected from
the group consisting of --O--CH.sub.3, --O--CH.sub.2--CH.sub.3,
--O--(CH.sub.2).sub.2--CH.sub.3, --O--CH(CH.sub.3).sub.2,
--O--(CH.sub.2).sub.3--CH.sub.3, --O--C(CH.sub.3), and
--O--CH.sub.2--CH(CH.sub.3).sub.2. A particularly preferred alkoxy
group is --O--CH(CH.sub.3).sub.2.
[0048] R.sup.1 is at each occurrence independently alkyl having
from 1 to 10 carbon atoms, said alkyl being substituted with at
least one electron-withdrawing group R.sup.A, or aryl having from 6
to 30 aromatic carbon ring atoms, said aryl being substituted with
at least one electron-withdrawing group R.sup.A.
[0049] Preferably R.sup.1 is at each occurrence independently a
group of any one of the following formulae (II-a) or (II-b)
##STR00001##
wherein [0050] b is at each occurrence independently an integer of
at least 1 and of at most 10, preferably of at most 5; [0051] c is
at each occurrence an integer of at least 1 and at most 2b+1, and
preferably is 2b+1; [0052] d is at each occurrence an integer of at
least 0 and at most 2b, and preferably is 0; with the provision
that the sum of c and d is 2b+1, i.e. c+d=2b+1; [0053] e is at each
occurrence independently an integer of at least 1 and of at most 5,
and preferably is 5; and R.sup.A is an electron-withdrawing group
as defined herein.
[0054] R.sup.A is an electron withdrawing group. Preferably R.sup.A
is at each occurrence independently selected from the group
consisting of --NO.sub.2, --CN, --F, --Cl, --Br, --I, --OAr.sup.2,
--OR.sup.3, --COR.sup.3, --SH, --SR.sup.3, --OH, --C.dbd.CR.sup.3,
--CH.dbd.CR.sup.3.sub.2, and alkyl having from 1 to 10 carbon
atoms, wherein one or more, preferably all, hydrogen atoms are
replaced by F, with Ar.sup.2 and R.sup.3 as defined herein. More
preferably R.sup.A is at each occurrence independently selected
from the group consisting of --CN, --F, --Cl, --Br, --I,
--OR.sup.3, and alkyl having from 1 to 10 carbon atoms, wherein one
or more, preferably all, hydrogen atoms are replaced by F, with
R.sup.3 as defined herein. Even more preferably R.sup.A is at each
occurrence independently selected from the group consisting of --F,
--OR.sup.3, and alkyl having from 1 to 10 carbon atoms, wherein one
or more, preferably all, hydrogen atoms are replaced by F, with
R.sup.3 as defined herein. Most preferably R.sup.A is F.
[0055] Ar.sup.2 is an aryl having from 6 to 30 carbon atoms,
preferably having from 6 to 20 carbon atoms, and most preferably is
phenyl. Preferably Ar.sup.2 is substituted with one or more
substituent selected from the group consisting of --CN, --F, --Cl,
--Br, --I, --OR.sup.3, and alkyl having from 1 to 10, preferably
from 1 to 5, carbon atoms, wherein one or more, preferably all,
hydrogen atoms are replaced by F, with R.sup.3 as defined
herein.
[0056] R.sup.3 is an alkyl having from 1 to 10, preferably from 1
to 5, carbon atoms, or alkyl having from 1 to 10, preferably from 1
to 5, carbon atoms, wherein one or more, preferably all, hydrogen
atoms are replaced by F.
[0057] Preferred examples of alkyl suitable as R.sup.3 may be
selected from the group consisting of methyl, ethyl, n-propyl,
iso-propyl, n-butyl, iso-butyl, tert-butyl and n-pentyl. Preferred
examples of fluorinated alkyl (i.e. alkyl wherein one or more,
preferably all, hydrogen atoms are replaced by F) suitable as
R.sup.3 may be selected from the group consisting of --CF.sub.3,
--C.sub.2F.sub.5, -n-C.sub.3F.sub.7 (i.e. n-propyl), and
-n-C.sub.4F.sub.9 (i.e. n-butyl).
[0058] Preferred examples of the compound of formula (I) may be
selected from the group consisting of the following formulae (I-1)
to (I-11)
##STR00002## ##STR00003##
[0059] with X as defined herein, and e being an integer of at least
1 and at most 10 (for example 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10).
[0060] Without wishing to be bound by theory it is believed that
the deposition of a compound of formula (I) onto the electrode will
result in the formation of one or more --Si--O-M- bonds (with M
being a metal atom comprised in the electrode).
[0061] Preferably the self-assembled monolayers of the present
invention may have a thickness (measured perpendicular to the
surface of such layer) from 1 to 10, more preferably from 1 to 5,
even more preferably from 1 to 3, and still even more preferably
from 1 to 2 molecular layers. Most preferably said thickness is
about one molecular layer.
[0062] The organic semiconducting material is not particularly
limited. Any organic semiconducting material may be used, such as
for example so-called "small molecules" or polymers. The term
"small molecules" refers to organic semiconducting compounds that
generally have a molecular weight of at most 1000 g mol.sup.-1,
preferably of at most 500 g mol.sup.-1.
[0063] The organic semiconducting material can either be an n-type
or p-type semiconducting material. Preferably, said organic
semiconducting material has a field effect transistor mobility of
at least 110.sup.-5 cm.sup.2 V.sup.-1 s.sup.-1.
[0064] Preferably the organic semiconducting layer is solid.
Preferably the semiconducting layer comprises, and preferably
consists of, one or more, preferably one, organic semiconducting
material. Preferably, said semiconducting material has a transistor
mobility of at least 110.sup.-5 cm.sup.2 V.sup.-1 s.sup.-1 and/or
the energy level of the highest occupied molecular orbital (HOMO)
of the semiconducting material is lower than the lower of the Fermi
energy levels of the first and second electrode materials.
[0065] The semiconducting layer preferably has a thickness of at
least 5 nm, more preferably of at least 10 nm, and of at most 20
.mu.m, more preferably of at most 15 .mu.m and most preferably of
at most 10 .mu.m.
[0066] The organic semiconducting material is preferably selected
from the group consisting of monomeric compounds (also referred to
as "small molecule"), oligomers, polymers or blends of any of
these, for example, including but not limited to blends of one or
more monomeric compounds, one or more oligomers or one or more
polymers. More preferably the organic semiconducting material is a
polymer or a blend of polymers. Most preferably the organic
semiconducting material is a polymer.
[0067] The type of organic semiconducting material is not
particularly limited. In general the organic semiconducting
material comprises a conjugated system. The term "conjugated
system" is herein used to denote a molecular entity or a part of a
molecular entity, the structure of which may be represented as a
system of alternating single and multiple bonds (see also
International Union of Pure and Applied Chemistry, Compendium of
Chemical Terminology, Gold Book, Version 2.3.3, 2014-02-24, pages
322-323).
[0068] An organic semiconducting material suited for use herein
may, for example, be represented by the following formula (V)
##STR00004##
[0069] wherein monomeric unit M and m are as defined herein. At
each occurrence M may be selected independently.
[0070] With regards to formula (V) m may be any integer from 1 to
100,000. For a monomer or monomeric unit m is 1. For an oligomer m
is at least 2 and at most 10. For a polymer m is at least 11.
[0071] Preferably, the organic semiconducting material comprises
one or more aromatic units. Expressed differently, with regards to
formula (V), M may be an aromatic unit. Such aromatic units
preferably comprise two or more, more preferably three or more
aromatic rings. Such aromatic rings may, for example, at each
occurrence independently be selected from the group consisting of
5-, 6-, 7- and 8-membered aromatic rings, with 5- and 6-membered
rings being particularly preferred.
[0072] These aromatic rings comprised in the organic semiconducting
material optionally comprise one or more heteroatoms selected from
Se, Te, P, Si, B, As, N, O or S, preferably from Si, N, O or S.
Further, these aromatic rings may optionally be substituted with
alkyl, alkoxy, polyalkoxy, thioalkyl, acyl, aryl or substituted
aryl groups, halogen, with fluorine being the preferred halogen,
cyano, nitro or an optionally substituted secondary or tertiary
alkylamine or arylamine represented by --N(R')(R''), where R' and
R'' are each independently H, an optionally substituted alkyl or an
optionally substituted aryl, alkoxy or polyalkoxy groups are
typically employed. Further, where R' and R'' is alkyl or aryl
these may be optionally fluorinated.
[0073] The aforementioned aromatic rings can be fused rings or
linked to each other by a conjugated linking group such as
--C(T.sub.1)=C(T.sub.2)-, --C.ident.C--, --N(R''')--, --N.dbd.N--,
(R''').dbd.N--, --N.dbd.C(R''')--, where T.sub.1 and T.sub.2 each
independently represent H, Cl, F, --C.ident.N or loweralkyl groups
such as C.sub.14 alkyl groups; R''' represents H, optionally
substituted alkyl or optionally substituted aryl. Further, where
R''' is alkyl or aryl, it may be optionally fluorinated.
[0074] Further preferred organic semiconducting materials may be
polymers or copolymers wherein the monomeric units M of formula (V)
may at each occurrence be independently selected from the group
consisting of formulae (A1) to (A83) and (D1) to (D142)
##STR00005## ##STR00006## ##STR00007## ##STR00008## ##STR00009##
##STR00010## ##STR00011## ##STR00012## ##STR00013## ##STR00014##
##STR00015## ##STR00016## ##STR00017## ##STR00018## ##STR00019##
##STR00020## ##STR00021## ##STR00022## ##STR00023## ##STR00024##
##STR00025## ##STR00026## ##STR00027## ##STR00028## ##STR00029##
##STR00030## ##STR00031## ##STR00032## ##STR00033## ##STR00034##
##STR00035##
[0075] wherein R.sup.101, R.sup.102, R.sup.103, R.sup.104,
R.sup.105, R.sup.106, R.sup.107 and R.sup.108 are independently of
each other selected from the group consisting of H and R.sup.S as
defined herein.
[0076] R.sup.S is at each occurrence independently a carbyl group
as defined herein and preferably selected from the group consisting
of any group R.sup.T as defined herein, hydrocarbyl having from 1
to 40 carbon atoms wherein the hydrocarbyl may be further
substituted with one or more groups R.sup.T, and hydrocarbyl having
from 1 to 40 carbon atoms comprising one or more heteroatoms
selected from the group consisting of N, O, S, P, Si, Se, As, Te or
Ge, with N, O and S being preferred heteroatoms, wherein the
hydrocarbyl may be further substituted with one or more groups
R.sup.T.
[0077] Preferred examples of hydrocarbyl suitable as R.sup.S may at
each occurrence be independently selected from phenyl, phenyl
substituted with one or more groups R.sup.T, alkyl and alkyl
substituted with one or more groups R.sup.T, wherein the alkyl has
at least 1, preferably at least 5 and has at most 40, more
preferably at most 30 or 25 or 20, even more preferably at most 15
and most preferably at most 12 carbon atoms. It is noted that for
example alkyl suitable as R.sup.S also includes fluorinated alkyl,
i.e. alkyl wherein one or more hydrogen is replaced by fluorine,
and perfluorinated alkyl, i.e. alkyl wherein all of the hydrogen
are replaced by fluorine.
[0078] R.sup.T is at each occurrence independently selected from
the group consisting of F, Br, Cl, --CN, --NC, --NCO, --NCS, --OCN,
--SCN, --C(O)NR.sup.0R.sup.00, --C(O)X.sup.0, --C(O)R.sup.0,
--NH.sub.2, --NR.sup.0R.sup.00, --SH, --SR.sup.0, --SO.sub.3H,
--SO.sub.2R.sup.0, --OH, --OR.sup.0, --NO.sub.2, --SF.sub.5 and
--SiR.sup.0R.sup.00R.sup.000. Preferred R.sup.T are selected from
the group consisting of F, Br, Cl, --CN, --NC, --NCO, --NCS, --OCN,
--SCN, --C(O)NR.sup.0R.sup.00, --C(O)X.sup.0, --C(O)R.sup.0,
--NH.sub.2, --NR.sup.0R.sup.00, --SH, --SR.sup.0, --OH, --OR.sup.0
and --SiR.sup.0R.sup.00R.sup.000. Most preferred R.sup.T is F.
[0079] R.sup.0, R.sup.00 and R.sup.000 are at each occurrence
independently of each other selected from the group consisting of
H, F and hydrocarbyl having from 1 to 40 carbon atoms. Said
hydrocarbyl preferably has at least 5 carbon atoms. Said
hydrocarbyl preferably has at most 30, more preferably at most 25
or 20, even more preferably at most 20, and most preferably at most
12 carbon atoms. Preferably, R.sup.0, R.sup.00 and R.sup.000 are at
each occurrence independently of each other selected from the group
consisting of H, F, alkyl, fluorinated alkyl, alkenyl, alkynyl,
phenyl and fluorinated phenyl. More preferably, R.sup.0, R.sup.00
and R.sup.000 are at each occurrence independently of each other
selected from the group consisting of H, F, alkyl, fluorinated,
preferably perfluorinated, alkyl, phenyl and fluorinated,
preferably perfluorinated, phenyl.
[0080] It is noted that for example alkyl suitable as R.sup.0,
R.sup.00 and R.sup.000 also includes perfluorinated alkyl, i.e.
alkyl wherein all of the hydrogen are replaced by fluorine.
Examples of suitable alkyls may be selected from the group
consisting of methyl, ethyl, n-propyl, iso-propyl, n-butyl,
iso-butyl, tert-butyl (or "t-butyl"), pentyl, hexyl, heptyl, octyl,
nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl,
hexadecyl, heptadecyl, octadecyl, nonadecyl and eicosyl
(--C.sub.20H.sub.41).
[0081] X.sup.0 is halogen. Preferably X.sup.0 is selected from the
group consisting of F, Cl and Br.
[0082] A hydrocarbyl group comprising a chain of 3 or more carbon
atoms and heteroatoms combined may be straight chain, branched
and/or cyclic, including spiro and/or fused rings.
[0083] Hydrocarbyl suitable as R.sup.S, R.sup.0, R.sup.00 and/or
R.sup.000 may be saturated or unsaturated. Examples of saturated
hydrocarbyl include alkyl. Examples of unsaturated hydrocarbyl may
be selected from the group consisting of alkenyl (including acyclic
and cyclic alkenyl), alkynyl, allyl, alkyldienyl, polyenyl, aryl
and heteroaryl.
[0084] Preferred hydrocarbyl suitable as R.sup.S, R.sup.0, R.sup.00
and/or R.sup.000 include hydrocarbyl comprising one or more
heteroatoms and may for example be selected from the group
consisting of alkoxy, alkylcarbonyl, alkoxycarbonyl,
alkylcarbonyloxy and alkoxycarbonyloxy, alkylaryloxy, arylcarbonyl,
aryloxycarbonyl, arylcarbonyloxy and aryloxycarbonyloxy.
[0085] Preferred examples of aryl and heteroaryl comprise mono-,
bi- or tricyclic aromatic or heteroaromatic groups that may also
comprise condensed rings.
[0086] Especially preferred aryl and heteroaryl groups may be
selected from the group consisting of phenyl, phenyl wherein one or
more CH groups are replaced by N, naphthalene, fluorene, thiophene,
pyrrole, preferably N-pyrrole, furan, pyridine, preferably 2- or
3-pyridine, pyrimidine, pyridazine, pyrazine, triazole, tetrazole,
pyrazole, imidazole, isothiazole, thiazole, thiadiazole, isoxazole,
oxazole, oxadiazole, thiophene, preferably 2-thiophene,
selenophene, preferably 2-selenophene, thieno[3,2-b]thiophene,
thieno[2,3-b]thiophene, dithienothiophene, furo[3,2-b]furan,
furo[2,3-b]furan, seleno[3,2-b]selenophene,
seleno[2,3-b]selenophene, thieno[3,2-b]selenophene,
thieno[3,2-b]furan, indole, isoindole, benzo[b]furan,
benzo[b]thiophene, benzo[1,2-b;4,5-b']dithiophene,
benzo[2,1-b;3,4-b']dithiophene, quinole, 2-methylquinole,
isoquinole, quinoxaline, quinazoline, benzotriazole, benzimidazole,
benzothiazole, benzisothiazole, benzisoxazole, benzoxadiazole,
benzoxazole and benzothiadiazole.
[0087] Preferred examples of an alkoxy group, i.e. a corresponding
alkyl group wherein the terminal CH.sub.2 group is replaced by
--O--, can be straight-chain or branched, preferably straight-chain
(or linear). Suitable examples of such alkoxy group may be selected
from the group consisting of methoxy, ethoxy, propoxy, butoxy,
pentoxy, hexoxy, heptoxy, octoxy, nonoxy, decoxy, undecoxy,
dodecoxy, tridecoxy, tetradecoxy, pentadecoxy, hexadecoxy,
heptadecoxy and octadecoxy.
[0088] Preferred examples of alkenyl, i.e. a corresponding alkyl
wherein two adjacent CH.sub.2 groups are replaced by --CH.dbd.CH--
can be straight-chain or branched. It is preferably straight-chain.
Said alkenyl preferably has 2 to 10 carbon atoms. Preferred
examples of alkenyl may be selected from the group consisting of
vinyl, prop-1-enyl, or prop-2-enyl, but-1-enyl, but-2-enyl or
but-3-enyl, pent-1-enyl, pent-2-enyl, pent-3-enyl or pent-4-enyl,
hex-1-enyl, hex-2-enyl, hex-3-enyl, hex-4-enyl or hex-5-enyl,
hept-1-enyl, hept-2-enyl, hept-3-enyl, hept-4-enyl, hept-5-enyl or
hept-6-enyl, oct-1-enyl, oct-2-enyl, oct-3-enyl, oct-4-enyl,
oct-5-enyl, oct-6-enyl or oct-7-enyl, non-1-enyl, non-2-enyl,
non-3-enyl, non-4-enyl, non-5-enyl, non-6-enyl, non-7-enyl,
non-8-enyl, dec-1-enyl, dec-2-enyl, dec-3-enyl, dec-4-enyl,
dec-5-enyl, dec-6-enyl, dec-7-enyl, dec-8-enyl and dec-9-enyl.
[0089] Especially preferred alkenyl groups are
C.sub.2-C.sub.7-1E-alkenyl, C.sub.4-C.sub.7-3E-alkenyl,
C.sub.5-C.sub.7-4-alkenyl, C.sub.6-C.sub.7-5-alkenyl and
C.sub.7-6-alkenyl, in particular C.sub.2-C.sub.7-1E-alkenyl,
C.sub.4-C.sub.7-3E-alkenyl and C.sub.5-C.sub.7-4-alkenyl. Examples
of particularly preferred alkenyl groups are vinyl, 1E-propenyl,
1E-butenyl, 1E-pentenyl, 1E-hexenyl, 1E-heptenyl, 3-butenyl,
3E-pentenyl, 3E-hexenyl, 3E-heptenyl, 4-pentenyl, 4Z-hexenyl,
4E-hexenyl, 4Z-heptenyl, 5-hexenyl, 6-heptenyl and the like.
Alkenyl groups having up to 5 C atoms are generally preferred.
[0090] Preferred examples of oxaalkyl, i.e. a corresponding alkyl
wherein one non-terminal CH.sub.2 group is replaced by --O--, can
be straight-chain or branched, preferably straight chain. Specific
examples of oxaalkyl may be selected from the group consisting of
2-oxapropyl (=methoxymethyl), 2-(=ethoxymethyl) or 3-oxabutyl
(=2-methoxyethyl), 2-, 3-, or 4-oxapentyl, 2-, 3-, 4-, or
5-oxahexyl, 2-, 3-, 4-, 5-, or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or
7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl and 2-, 3-, 4-,
5-, 6-, 7-, 8- or 9-oxadecyl.
[0091] Preferred examples of carbonyloxy and oxycarbonyl, i.e. a
corresponding alkyl wherein one CH.sub.2 group is replaced by --O--
and one of the thereto adjacent CH.sub.2 groups is replaced by
--C(O)--. may be selected from the group consisting of acetyloxy,
propionyloxy, butyryloxy, pentanoyloxy, hexanoyloxy,
acetyloxymethyl, propionyloxymethyl, butyryloxymethyl,
pentanoyloxymethyl, 2-acetyloxyethyl, 2-propionyloxyethyl,
2-butyryloxyethyl, 3-acetyloxypropyl, 3-propionyloxypropyl,
4-acetyloxybutyl, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl,
butoxycarbonyl, pentoxycarbonyl, methoxycarbonylmethyl,
ethoxy-carbonylmethyl, propoxycarbonylmethyl, butoxycarbonylmethyl,
2-(methoxycarbonyl)ethyl, 2-(ethoxycarbonyl)ethyl,
2-(propoxycarbonyl)ethyl, 3-(methoxycarbonyl)propyl,
3-(ethoxycarbonyl)propyl, and 4-(methoxycarbonyl)-butyl.
[0092] Preferred examples of thioalkyl, i.e where one CH.sub.2
group is replaced by --S--, may be straight-chain or branched,
preferably straight-chain. Suitable examples may be selected from
the group consisting of thiomethyl (--SCH.sub.3), 1-thioethyl
(--SCH.sub.2CH.sub.3), 1-thiopropyl (--SCH.sub.2CH.sub.2CH.sub.3),
1-(thiobutyl), 1-(thiopentyl), 1-(thiohexyl), 1-(thioheptyl),
1-(thiooctyl), 1-(thiononyl), 1-(thiodecyl), 1-(thioundecyl) and
1-(thiododecyl).
[0093] A fluoroalkyl group is preferably perfluoroalkyl
C.sub.iF.sub.2i+1, wherein i is an integer from 1 to 15, in
particular CF.sub.3, C.sub.2F.sub.5, C.sub.3F.sub.7,
C.sub.4F.sub.9, C.sub.5F.sub.11, C.sub.6F.sub.13, C.sub.7F.sub.15
or C.sub.8F.sub.17, very preferably C.sub.6F.sub.13, or partially
fluorinated alkyl, in particular 1,1-difluoroalkyl, all of which
are straight-chain or branched.
[0094] Alkyl, alkoxy, alkenyl, oxaalkyl, thioalkyl, carbonyl and
carbonyloxy groups can be achiral or chiral groups. Particularly
preferred chiral groups are 2-butyl (=1-methylpropyl),
2-methylbutyl, 2-methylpentyl, 3-methylpentyl, 2-ethylhexyl,
2-propylpentyl, 2-butyloctyl, 2-hexyldecyl, 2-octyldodecyl,
7-decylnonadecyl, in particular 2-methylbutyl, 2-methylbutoxy,
2-methylpentoxy, 3-methylpentoxy, 2-ethyl-hexoxy, 1-methylhexoxy,
2-octyloxy, 2-oxa-3-methylbutyl, 3-oxa-4-methyl-pentyl,
4-methylhexyl, 2-butyloctyl, 2-hexyldecyl, 2-octyldodecyl,
7-decylnonadecyl, 3,8-dimethyloctyl, 2-hexyl, 2-octyl, 2-nonyl,
2-decyl, 2-dodecyl, 6-meth-oxyoctoxy, 6-methyloctoxy,
6-methyloctanoyloxy, 5-methylheptyloxy-carbonyl,
2-methylbutyryloxy, 3-methylvaleroyloxy, 4-methylhexanoyloxy,
2-chloropropionyloxy, 2-chloro-3-methylbutyryloxy,
2-chloro-4-methyl-valeryl-oxy, 2-chloro-3-methylvaleryloxy,
2-methyl-3-oxapentyl, 2-methyl-3-oxa-hexyl, 1-methoxypropyl-2-oxy,
1-ethoxypropyl-2-oxy, 1-propoxypropyl-2-oxy, 1-butoxypropyl-2-oxy,
2-fluorooctyloxy, 2-fluorodecyloxy, 1,1,1-trifluoro-2-octyloxy,
1,1,1-trifluoro-2-octyl, 2-fluoromethyloctyloxy for example. Most
preferred is 2-ethylhexyl.
[0095] Preferred achiral branched groups are isopropyl, isobutyl
(=methylpropyl), isopentyl (=3-methylbutyl), tert. butyl,
isopropoxy, 2-methyl-propoxy and 3-methylbutoxy.
[0096] In a preferred embodiment, the organyl groups are
independently of each other selected from primary, secondary or
tertiary alkyl or alkoxy with 1 to 30 C atoms, wherein one or more
H atoms are optionally replaced by F, or aryl, aryloxy, heteroaryl
or heteroaryloxy that is optionally alkylated or alkoxylated and
has 4 to 30 ring atoms. Very preferred groups of this type are
selected from the group consisting of the following formulae
##STR00036##
wherein "ALK" denotes optionally fluorinated, preferably linear,
alkyl or alkoxy with 1 to 20, preferably 1 to 12 C-atoms, in case
of tertiary groups very preferably 1 to 9 C atoms, and the dashed
line denotes the link to the ring to which these groups are
attached. Especially preferred among these groups are those wherein
all ALK subgroups are identical.
[0097] Further, in some preferred embodiments in accordance with
the present invention, the organic semiconducting materials are
polymers or copolymers that encompass one or more repeating units,
e.g. M in formula (I), selected from thiophene-2,5-diyl,
3-substituted thiophene-2,5-diyl, optionally substituted
thieno[2,3-b]thiophene-2,5-diyl, optionally substituted
thieno[3,2-b]thiophene-2,5-diyl, selenophene-2,5-diyl, or
3-substituted selenophene-2,5-diyl.
[0098] Preferred examples of organic semiconducting materials
comprise one or more monomeric units selected from the group
consisting of formulae (A1) to (A83) and one or more monomeric
units selected from the group consisting of formulae (D1) to
(D142).
[0099] Further preferred examples of organic semiconductor
materials that can be used in this invention include compounds,
oligomers and derivatives of compounds selected from the group
consisting of conjugated hydrocarbon polymers such as polyacene,
polyphenylene, poly(phenylene vinylene), polyfluorene including
oligomers of those conjugated hydrocarbon polymers; condensed
aromatic hydrocarbons, such as, tetracene, chrysene, pentacene,
pyrene, perylene, coronene, or soluble, substituted derivatives of
these; oligomeric para substituted phenylenes such as
p-quaterphenyl (p-4P), p-quinquephenyl (p-5P), p-sexiphenyl (p-6P),
or soluble substituted derivatives of these; conjugated
heterocyclic polymers such as poly(3-substituted thiophene),
poly(3,4-bisubstituted thiophene), optionally substituted
polythieno[2,3-b]thiophene, optionally substituted
polythieno[3,2-b]thiophene, poly(3-substituted selenophene),
polybenzothiophene, polyisothianapthene, poly(N-substituted
pyrrole), poly(3-substituted pyrrole), poly(3,4-bisubstituted
pyrrole), polyfuran, polypyridine, poly-1,3,4-oxadiazoles,
polyisothianaphthene, poly(N-substituted aniline),
poly(2-substituted aniline), poly(3-substituted aniline),
poly(2,3-bisubstituted aniline), polyazulene, polypyrene;
pyrazoline compounds; polyselenophene; polybenzofuran; polyindole;
polypyridazine; benzidine compounds; stilbene compounds; triazines;
substituted metallo- or metal-free porphines, phthalocyanines,
fluorophthalocyanines, naphthalocyanines or
fluoronaphthalocyanines; C.sub.60 and C.sub.70 fullerenes;
N,N'-dialkyl, substituted dialkyl, diaryl or substituted
diaryl-1,4,5,8-naphthalenetetracarboxylic diimide and fluoro
derivatives; N,N'-dialkyl, substituted dialkyl, diaryl or
substituted diaryl 3,4,9,10-perylenetetracarboxylicdiimide;
bathophenanthroline; diphenoquinones; 1,3,4-oxadiazoles;
11,11,12,12-tetracyanonaptho-2,6-quinodimethane;
a,a'-bis(di-thieno[3,2-b2',3'-d]thiophene); 2,8-dialkyl,
substituted dialkyl, diaryl or substituted diaryl
anthradithiophene; 2,2'-bisbenzo[1,2-b:4,5-b']dithiophene. Where a
liquid deposition technique of the OSC is desired, compounds from
the above list and derivatives thereof are limited to those that
are soluble in an appropriate solvent or mixture of appropriate
solvents.
[0100] Other preferred examples of organic semiconducting materials
may be selected from the group consisting of substituted
oligoacenes, such as pentacene, tetracene or anthracene, or
heterocyclic derivatives thereof. Bis(trialkylsilylethynyl)
oligoacenes or bis(trialkylsilylethynyl) heteroacenes, as disclosed
for example in U.S. Pat. No. 6,690,029 or WO 2005/055248 A1 or U.S.
Pat. No. 7,385,221, are also useful.
[0101] Further preferred organic semiconducting materials are
selected from the group consisting of small molecules or monomers
of the tetra-heteroaryl indacenodithiophene-based structural unit
as disclosed in WO 2016/015804 A1, and polymers or copolymers
comprising one or more repeating units thereof.
[0102] Also preferred organic semiconducting materials may be
selected from the group of small molecules or monomers or polymers
comprising a 2,7-(9,9')spirobifluorene moiety, optionally
substituted and preferably substituted with amino groups. Such
spirobifluorenes are, for example, disclosed in WO 97/39045.
Examples of spirobifluorenes suitable for use as monomeric unit M
of formula (V) may be selected from the group consisting of
formulae (VI-1) to (VI-7)
##STR00037##
[0103] wherein each of the hydrogen atoms may independently of any
other be as defined herein in respect to R.sup.101 and each
asterisk "*" independently may denote a bond to neighboring moiety
(for example in a polymer) or may denote a bond to a group as
defined above for R.sup.101 (for example in a compound of formula
(V-a) or (V-b)). In respect to formulae (VI-1) to (VI-7) preferred
substituents, including the ones for "*", may be selected from the
group consisting of alkyl having from 1 to 20 carbon atoms; aryl
having from 6 to 20 carbon atoms, said aryl being optionally
substituted with alkyl or alkoxy having from 1 to 20, preferably 1
to 10 carbon atoms; and NR.sup.110R.sup.111 with R.sup.110 and
R.sup.111 being independently of each other selected from the group
consisting of alkyl having from 1 to 20 carbon atoms, aryl having
from 6 to 20 carbon atoms, said aryl being optionally substituted
with alkyl or alkoxy having from 1 to 20, preferably 1 to 10 carbon
atoms, most preferably R.sup.110 and R.sup.111 being independently
of each other selected from methyl, ethyl, n-propyl, iso-propyl,
n-butyl, iso-butyl, tert-butyl, pentyl, methoxy, ethoxy, n-propoxy,
iso-propoxy n-butoxy, iso-butoxy, tert-butoxy and pentoxy.
[0104] In a one aspect the present semiconducting material may, for
example, be a small molecule, i.e. a compound comprising one (i.e.
m=1) structural unit of formula (V) and two inert chemical groups
R.sup.a and R.sup.b. Such a small molecule may for example be
represented by formula (I-a)
R.sup.a-M-R.sup.b (V-a)
wherein M is as defined herein and R.sup.a and R.sup.b are inert
chemical groups. Such inert chemical groups R.sup.a and R.sup.b may
independently of each other be selected from the group consisting
of hydrogen, fluorine, alkyl having from 1 to 10 carbon atoms,
alkyl having from 1 to 10 carbon atoms wherein one or more, for
example all, hydrogen has been replaced with fluorine, aromatic
ring systems of from 5 to 30 carbon atoms and aromatic ring systems
of from 5 to 30 carbon atoms wherein one or more hydrogen atom may
independently of any other be replaced by fluorine or alkyl having
from 1 to 10 carbon atoms.
[0105] Further preferred p-type OSCs are copolymers comprising
electron acceptor and electron donor units. Preferred copolymers of
this preferred embodiment are for example copolymers comprising one
or more benzo[1,2-b:4,5-b']dithiophene-2,5-diyl units that are
preferably 4,8-disubstituted by one or more groups R as defined
above, and further comprising one or more aryl or heteroaryl units
selected from Group A and Group B, preferably comprising at least
one unit of Group A and at least one unit of Group B, wherein Group
A consists of aryl or heteroaryl groups having electron donor
properties and Group B consists of aryl or heteroaryl groups having
electron acceptor properties, and preferably Group A consists of
selenophene-2,5-diyl, thiophene-2,5-diyl,
thieno[3,2-b]thiophene-2,5-diyl, thieno[2,3-b]thiophene-2,5-diyl,
selenopheno[3,2-b]selenophene-2,5-diyl,
selenopheno[2,3-b]selenophene-2,5-diyl,
selenopheno[3,2-b]thiophene-2,5-diyl,
selenopheno[2,3-b]thiophene-2,5-diyl,
benzo[1,2-b:4,5-b']dithiophene-2,6-diyl, 2,2-dithiophene,
2,2-diselenophene, dithieno[3,2-b:2',3'-d]silole-5,5-diyl,
4H-cyclopenta[2,1-b:3,4-b']dithiophene-2,6-diyl,
2,7-di-thien-2-yl-carbazole, 2,7-di-thien-2-yl-fluorene,
indaceno[1,2-b:5,6-b']dithiophene-2,7-diyl,
benzo[1'',2'':4,5;4'',5'':4',5']bis(silolo[3,2-b:3',2'-b']thiophene)-2,7--
diyl, 2,7-di-thien-2-yl-indaceno[1,2-b:5,6-b']dithiophene,
2,7-di-thien-2-yl-benzo[1'',2'':4,5;4'',5'':4',5']bis(silolo[3,2-b:3',2'--
b']thiophene)-2,7-diyl, and
2,7-di-thien-2-yl-phenanthro[1,10,9,8-c,d,e,f,g]carbazole, all of
which are optionally substituted by one or more, preferably one or
two groups R as defined above, and
[0106] Group B consists of benzo[2,1,3]thiadiazole-4,7-diyl,
5,6-dialkyl-benzo[2,1,3]thiadiazole-4,7-diyl,
5,6-dialkoxybenzo[2,1,3]thiadiazole-4,7-diyl,
benzo[2,1,3]selenadiazole-4,7-diyl,
5,6-dialkoxy-benzo[2,1,3]selenadiazole-4,7-diyl,
benzo[1,2,5]thiadiazole-4,7,diyl,
benzo[1,2,5]selenadiazole-4,7,diyl,
benzo[2,1,3]oxadiazole-4,7-diyl,
5,6-dialkoxybenzo[2,1,3]oxadiazole-4,7-diyl,
2H-benzotriazole-4,7-diyl, 2,3-dicyano-1,4-phenylene,
2,5-dicyano,1,4-phenylene, 2,3-difluro-1,4-phenylene,
2,5-difluoro-1,4-phenylene, 2,3,5,6-tetrafluoro-1,4-phenylene,
3,4-difluorothiophene-2,5-diyl, thieno[3,4-b]pyrazine-2,5-diyl,
quinoxaline-5,8-diyl, thieno[3,4-b]thiophene-4,6-diyl,
thieno[3,4-b]thiophene-6,4-diyl, and
3,6-pyrrolo[3,4-c]pyrrole-1,4-dione, all of which are optionally
substituted by one or more, preferably one or two groups R as
defined above.
[0107] In other preferred embodiments of the present invention, the
OSC materials are substituted oligoacenes such as pentacene,
tetracene or anthracene, or heterocyclic derivatives thereof.
Bis(trialkylsilylethynyl) oligoacenes or bis(trialkylsilylethynyl)
heteroacenes, as disclosed for example in U.S. Pat. No. 6,690,029
or WO 2005/055248 A1 or U.S. Pat. No. 7,385,221, are also
useful.
[0108] Further preferred organic semiconducting materials are
selected from the group consisting of small molecules or monomers
of the tetra-heteroaryl indacenodithiophene-based structural unit
as disclosed in WO 2016/015804 A1, and polymers or copolymers
comprising one or more repeating units thereof, such as, for
example, one of the following polymers (P-1) to (P-3):
##STR00038##
[0109] Depending upon the intended application the present organic
semiconducting material may also comprise other components, such
as, for example, a fullerene or modified fullerene. In such blends
of polymer and fullerene the ratio polymer:fullerene is preferably
from 5:1 to 1:5 by weight, more preferably from 1:1 to 1:3 by
weight, most preferably 1:1 to 1:2 by weight. Suitable fullerenes
may, for example, be indene-C.sub.60-fullerene bis-adduct like
ICBA, or a (6,6)-phenyl-butyric acid methyl ester derivatized
methano C.sub.60 fullerene, also known as "PCBM-C.sub.60" or
"C.sub.60PCBM", as disclosed for example in G. Yu, J. Gao, J. C.
Hummelen, F. Wudl, A. J. Heeger, Science 1995, Vol. 270, p. 1789 ff
and having the structure shown below, or structural analogous
compounds with e.g. a C.sub.61 fullerene group, a C.sub.70
fullerene group, or a C.sub.71 fullerene group, or an organic
polymer (see for example Coakley, K. M. and McGehee, M. D. Chem.
Mater. 2004, 16, 4533).
##STR00039##
[0110] Organic semiconducting materials may be purchased from
commercial sources, such as SigmaAldrich or Merck KGaA (Darmstadt,
Germany), or may be synthesized according to published
syntheses.
[0111] In a further aspect the present semiconducting material may
be an oligomer or a polymer as defined above. Such oligomers and
polymers may be synthesized according to or in analogy to methods
that are known to the skilled person and are described in the
literature from monomers as described in the following.
[0112] Monomers that are suitable for the synthesis of the present
oligomers and polymers may be selected from compounds comprising a
structural unit of formula (I) and at least one reactive chemical
group R.sup.C which may be selected from the group consisting of
Cl, Br, I, O-tosylate, O-triflate, O-mesylate, O-nonaflate,
--SiMe.sub.2F, --SiMeF.sub.2, --O--SO.sub.2Z.sup.1,
--B(OZ.sup.2).sub.2, --CZ.sup.3.dbd.C(Z.sup.3).sub.2, --C.ident.CH,
--C.ident.CSi(Z.sup.1).sub.3, --ZnX.sup.00 and --Sn(Z.sup.4).sub.3,
preferably --B(OZ.sup.2).sub.2 or --Sn(Z.sup.4).sub.3, wherein
X.sup.00 is as defined herein, and Z.sup.1, Z.sup.2, Z.sup.3 and
Z.sup.4 are selected from the group consisting of alkyl and aryl,
preferably alkyl having from 1 to 10 carbon atoms, each being
optionally substituted with R.sup.0 as defined herein, and two
groups Z.sup.2 may also together form a cyclic group. Alternatively
such a monomer may comprise two reactive chemical groups and is,
for example, represented by formula (V-b)
R.sup.c-M-R.sup.d (V-b)
wherein M is as defined herein and R.sup.C and R.sup.d are reactive
chemical groups as defined above in respect to R.sup.C. Such
monomers may generally be prepared according to methods well known
to the person skilled in the art.
[0113] X.sup.00 is halogen. Preferably X.sup.00 is selected from
the group consisting of F, Cl and Br. Most preferably X.sup.00 is
Br.
[0114] Preferred aryl-aryl coupling and polymerisation methods used
in the processes described herein may, for example, be one or more
of Yamamoto coupling, Kumada coupling, Negishi coupling, Suzuki
coupling, Stille coupling, Sonogashira coupling, Heck coupling,
C--H activation coupling, Ullmann coupling and Buchwald coupling.
Especially preferred are Suzuki coupling, Negishi coupling, Stille
coupling and Yamamoto coupling. Suzuki coupling is described for
example in WO 00/53656 A1. Negishi coupling is described for
example in J. Chem. Soc., Chem. Commun., 1977, 683-684. Yamamoto
coupling is described for example in T. Yamamoto et al., Prog.
Polym. Sci., 1993, 17, 1153-1205, or WO 2004/022626 A1, and Stille
coupling is described for example in Z. Bao et al., J. Am. Chem.
Soc., 1995, 117, 12426-12435. For example, when using Yamamoto
coupling, monomers having two reactive halide groups are preferably
used. When using Suzuki coupling, compounds of formula (I-b) having
two reactive boronic acid or boronic acid ester groups or two
reactive halide groups are preferably used. When using Stille
coupling, monomers having two reactive stannane groups or two
reactive halide groups are preferably used. When using Negishi
coupling, monomers having two reactive organozinc groups or two
reactive halide groups are preferably used.
[0115] Preferred catalysts, especially for Suzuki, Negishi or
Stille coupling, are selected from Pd(0) complexes or Pd(II) salts.
Preferred Pd(0) complexes are those bearing at least one phosphine
ligand, for example Pd(Ph.sub.3P).sub.4. Another preferred
phosphine ligand is tris(ortho-tolyl)phosphine, for example
Pd(o-Tol.sub.3P).sub.4. Preferred Pd(II) salts include palladium
acetate, for example Pd(OAc).sub.2. Alternatively the Pd(0) complex
can be prepared by mixing a Pd(0) dibenzylideneacetone complex, for
example tris(dibenzyl-ideneacetone)dipalladium(0),
bis(dibenzylideneacetone)-palladium(0), or Pd(II) salts e.g.
palladium acetate, with a phosphine ligand, for example
triphenylphosphine, tris(ortho-tolyl)phosphine or
tri(tert-butyl)phosphine. Suzuki polymerisation is performed in the
presence of a base, for example sodium carbonate, potassium
carbonate, lithium hydroxide, potassium phosphate or an organic
base such as tetraethylammonium carbonate or tetraethylammonium
hydroxide. Yamamoto polymerisation employs a Ni(0) complex, for
example bis(1,5-cyclooctadienyl)nickel(0).
[0116] Suzuki and Stille polymerisation may be used to prepare
homopolymers as well as statistical, alternating and block random
copolymers. Statistical or block copolymers can be prepared for
example from the above monomers of formula (I-b), wherein one of
the reactive groups is halogen and the other reactive group is a
boronic acid, boronic acid derivative group or and alkylstannane.
The synthesis of statistical, alternating and block copolymers is
described in detail for example in WO 03/048225 A2 or WO
2005/014688 A2.
[0117] As alternatives to halogens as described above, leaving
groups of formula --O--SO.sub.2Z.sup.1 can be used wherein Z.sup.1
is as described above. Particular examples of such leaving groups
are tosylate, mesylate and triflate.
[0118] Where appropriate and needed, for example, to modify the
rheological properties as is described for example in WO
2005/055248 A1, some embodiments of the present invention employ
organic semiconducting compositions that include one or more
organic binders.
[0119] The binder, which is typically a polymer, may comprise
either an insulating binder or a semiconducting binder, or mixtures
thereof, may be referred to herein as the organic binder, the
polymeric binder, or simply the binder.
[0120] Preferred binders according to the present invention are
materials of low permittivity, that is, those having a permittivity
.epsilon. of 3.3 or less. The organic binder preferably has a
permittivity .epsilon. of 3.0 or less, more preferably 2.9 or less.
Preferably the organic binder has a permittivity .epsilon. of 1.7
or more. It is especially preferred that the permittivity of the
binder is in the range from 2.0 to 2.9. Whilst not wishing to be
bound by any particular theory it is believed that the use of
binders with a permittivity .epsilon. of greater than 3.3, may lead
to a reduction in the OSC layer mobility in an electronic device,
for example, in an OFET. In addition, high permittivity binders
could also result in increased current hysteresis of the device,
which is undesirable.
[0121] Examples of suitable organic binders include polystyrene, or
polymers or copolymers of styrene and .alpha.-methyl styrene; or
copolymers including styrene, .alpha.-methylstyrene and butadiene
may suitably be used. Further examples of suitable binders are
disclosed for example in US 2007/0102696 A1.
[0122] In one type of preferred embodiment, the organic binder is
one in which at least 95%, more preferably at least 98% and
especially all of the atoms consist of hydrogen, fluorine and
carbon atoms.
[0123] The binder is preferably capable of forming a film, more
preferably a flexible film.
[0124] The binder can also be selected from crosslinkable binders
such as acrylates, epoxies, vinylethers, and thiolenes, preferably
having a sufficiently low permittivity, very preferably of 3.3 or
less. The binder can also be mesogenic or liquid crystalline.
[0125] In another preferred embodiment the binder is a
semiconducting binder, which contains conjugated bonds, especially
conjugated double bonds and/or aromatic rings. Suitable and
preferred binders are for example polytriarylamines as disclosed
for example in U.S. Pat. No. 6,630,566.
[0126] The proportions of binder to OSC is typically 20:1 to 1:20
by weight, preferably 10:1 to 1:10 more preferably 5:1 to 1:5,
still more preferably 3:1 to 1:3 further preferably 2:1 to 1:2 and
especially 1:1. Dilution of the compound of formula (V) in the
binder has been found to have little or no detrimental effect on
the charge mobility, in contrast to what would have been expected
from the prior art.
[0127] The present organic electronic device may optionally
comprise one or more substrates. Such substrate is not particularly
limited and may be any suitable material that is inert under use
conditions. Examples of such materials are glass and polymeric
materials. Preferred polymeric material include but are not limited
to alkyd resins, allyl esters, benzocyclobutenes,
butadiene-styrene, cellulose, cellulose acetate, epoxide, epoxy
polymers, ethylene-chlorotrifluoro ethylene copolymers,
ethylene-tetra-fluoroethylene copolymers, fiber glass enhanced
polymers, fluorocarbon polymers,
hexafluoropropylenevinylidene-fluoride copolymer, high density
polyethylene, parylene, polyamide, polyimide, polyaramid,
polydimethylsiloxane, polyethersulphone, polyethylene,
polyethylenenaphthalate, polyethyleneterephthalate, polyketone,
polymethylmethacrylate, polypropylene, polystyrene, polysulphone,
polytetrafluoroethylene, polyurethanes, polyvinylchloride,
polycycloolefin, silicone rubbers, and silicones. Of these
polyethyleneterephthalate, polyimide, polycycloolefin and
polyethylenenaphthalate materials are more preferred. Additionally,
for some embodiments of the present invention the substrate can be
any suitable material, for example a polymeric material, metal or
glass material coated with one or more of the above listed
materials or coated with one or more metal, such as for example
titanium. It will be understood that in forming such a substrate,
methods such as extruding, stretching, rubbing or photochemical
techniques can be employed to provide a homogeneous surface for
device fabrication as well as to provide pre-alignment of an
organic semiconductor material in order to enhance carrier mobility
therein. Alternatively, the substrate can be a polymeric material,
metal or glass coated with one or more of the above polymeric
materials.
[0128] A suitable substrate may, for example, be transparent or
semi-transparent. A suitable substrate may, for example, also be
flexible or non-flexible.
[0129] Said substrate may, for example, serve as support and
preferably be adjacent to a first electrode layer. Said substrate
may, for example, also serve as support for the planarization layer
holding the first electrode layer. In general, a substrate may be
introduced into the electronic device between or adjacent to any
layer and placed such that it serves best to support the device
and/or be best placed with regards to manufacturing
requirements.
[0130] Additionally the present organic electronic device may
optionally comprise further layers acting as charge transport
layers. Exemplary charge transport layers may act as hole
transporting layer and/or electron blocking layer, or electron
transporting layer and/or hole blocking layer. Generally--if
present--such layers are between the electrodes and the organic
semiconducting layer.
[0131] Suitable materials for a hole transporting and/or electron
blocking layer may be selected from the group consisting of metal
oxides, like for example, zinc tin oxide (ZTO), MoOx, NiOx, a
conjugated polymer electrolyte, like for example PEDOT:PSS, a
conjugated polymer, like for example polytriarylamine (PTAA), an
organic compound, like for example
N,N'-diphenyl-N,N'-bis(I-naphthyl)(1,1'-biphenyl)-4,4'diamine
(NPB),
N,N'-diphenyl-N,N'-(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine
(TPD).
[0132] Suitable materials for a hole blocking and/or electron
transporting layer may be selected from the group consisting of
metal oxides, such as for example, ZnOx, TiOx, a salt, like for
example LiF, NaF, CsF, a conjugated polymer electrolyte, like for
example poly[3-(6-trimethylammoniumhexyl)thiophene],
poly(9,9-bis(2-ethylhexyl)-fluorene]-b-poly[3-(6-trimethylammoniumhexyl)t-
hiophene], or
poly[(9,9-bis(3'-(N,N-dimethyl-amino)propyl)-2,7-fluorene)-alt-2,7-(9,9-d-
ioctyl-fluorene)] or an organic compound, like for example
tris(8-quinolinolato)-aluminium(III) (Alq.sub.3),
4,7-diphenyl-1,10-phenanthroline.
[0133] The present organic electronic device may, for example, be
selected from the group consisting of organic field effect
transistors (OFET), organic thin film transistors (OTFT), organic
light emitting diodes (OLED), organic light emitting transistors
(OLET), organic photovoltaic devices (OPV), organic photodetectors
(OPD), organic solar cells, laser diodes, Schottky diodes,
photoconductors and photodetectors. Preferably the present organic
electronic device is an organic field effect transistor (PFET) or
an organic thin film transistor (OTFT).
[0134] A preferred example of the present organic electronic device
is an organic field effect transistor, preferably comprising a gate
electrode, a source electrode, a drain electrode, an insulating
layer (preferably a gate insulating layer), and an organic
semiconducting layer. Optionally an organic field effect transistor
may also comprise one or more selected from the group consisting of
substrate and charge transport layer. These layers in the OFET
device may be arranged in any sequence, provided that the source
electrode and the drain electrode are separated from the gate
electrode by the insulating layer, the gate electrode and the
semiconductor layer both contact the insulating layer, and the
source electrode and the drain electrode both contact the
semiconducting layer with the surface treatment layer
in-between.
[0135] The OFET device according to the present invention can be a
top gate device or a bottom gate device. Suitable structures of an
OFET device are known to the skilled person and are described in
the literature, for example in US 2007/0102696 A1.
[0136] FIG. 1 shows a schematic representation of a typical top
gate OFET according to the present invention, including source (S)
and drain (D) electrodes (2) provided on a substrate (I), a
self-assembled monolayer (3) formed by depositing a compound of
formula (I) as defined herein provided on the S/D electrodes, a
layer of organic semiconducting material (4) provided on the S/D
electrodes and the self-assembled monolayer (3), a layer of
dielectric material (5) as gate insulator layer provided on the
organic semiconducting layer (4), a gate electrode (6) provided on
the gate insulator layer (5), and an optional passivation or
protection layer (7) provided on the gate electrode (6) to shield
it from further layers or devices that may be provided later or to
protect it from environmental influence. The area between the
source and drain electrodes (2), indicated by the double arrow, is
the channel area.
[0137] FIG. 2 shows a schematic representation of a typical bottom
gate-bottom contact OFET according to the present invention,
including a gate electrode (6) provided on a substrate (I), a layer
of dielectric material (5) (gate insulator layer) provided on the
gate electrode (4), source (S) and drain (D) electrodes (2)
provided on the gate insulator layer (6), a self-assembled
monolayer (3) formed by depositing a compound of formula (I) as
defined herein provided on the S/D electrodes, a layer of an
organic semiconducting material (4) provided on the S/D electrodes
and the self-assembled monolayer (3), and an optional protection or
passivation layer (7) provided on the organic semiconducting layer
(4) to shield it from further layers or devices that may be later
provided or protect it from environmental influences.
[0138] In an OFET device according to the present invention, the
dielectric material for the gate insulator layer is preferably a
solution processable material. For the dielectric that is in direct
contact with the semiconductor. Especially preferred are organic
dielectric materials having a dielectric constant from 1.0 to 5.0,
very preferably from 1.8 to 4.0 ("low k materials"), as disclosed
for example in US 2007/0102696 A1 or U.S. Pat. No. 7,095,044. For
an optional second dielectric layer the dielectric constant is not
restricted, but preferably is fairly high in order to increase the
device's capacitance.
[0139] Preferably the gate insulator layer is deposited, e.g. by
spin-coating, doctor blading, wire bar coating, spray or dip
coating or other known methods, from a formulation comprising an
insulator material and one or more solvents with one or more fluoro
atoms (fluorosolvents), preferably a perfluorosolvent. A suitable
perfluorosolvent is e.g. FC75.RTM. (available from Acros, catalogue
number 12380). Other suitable fluoropolymers and fluorosolvents are
known in prior art, like for example the perfluoropolymers Teflon
AF.RTM. 1600 or 2400 (from DuPont) or Fluoropel.RTM. (from Cytonix)
or the perfluorosolvent FC 43.RTM. (Acros, No. 12377). Especially
preferred are organic dielectric materials having a dielectric
constant from 1.0 to 5.0, very preferably from 1.8 to 4.0 ("low k
materials"), as disclosed for example in US 2007/0102696 A1 or U.S.
Pat. No. 7,095,044.
[0140] The present transistor device may also be a complementary
organic thin film transistor (CTFT) comprising a layer of a p-type
semiconductor material as well as a layer of an n-type
semiconductor material.
[0141] In general terms, the present application also relates to a
method for producing the present organic electronic device as
described above, said method comprising the steps of [0142] (a)
providing an electrode as defined herein, optionally on a substrate
as defined herein; [0143] (b) depositing onto said electrode a
formulation comprising the compound of formula (I) as defined
herein and an alcohol of formula R.sup.2--OH as defined herein to
obtain the self-assembled monolayer; and [0144] (c) depositing onto
said self-assembled monolayer an organic semiconducting material to
obtain an organic semiconducting layer.
[0145] In step (b), the formulation may, for example, be deposited
onto the electrode by vacuum or vapor deposition methods or by
liquid coating methods. Exemplary deposition methods include
physical vapor deposition (PVD), chemical vapor deposition (CVD),
sublimation or liquid coating methods. Liquid coating methods are
preferred. Particularly preferred are solvent-based liquid coating
methods.
[0146] In solvent-based liquid coating a formulation, which
comprises the compound of formula (I) as defined herein and an
alcohol of formula R.sup.2--OH as defined herein (or the respective
reaction product(s) of the compound of formula (I) as defined
herein and an alcohol of formula R.sup.2--OH as defined herein), is
deposited onto the metal surface or the metal oxide surface.
Optionally, following deposition the solvent may be at least
partially evaporated. Preferred solvent-based liquid coating
methods include, without limitation, dip coating, spin coating, ink
jet printing, letter-press printing, screen printing, doctor blade
coating, roller printing, reverse-roller printing, offset
lithography printing, flexographic printing, gravure printing, web
printing, spray coating, brush coating and pad printing.
[0147] In addition to the alcohol of formula R.sup.2--OH as defined
herein, the formulation may comprise one or more further suitable
solvent. Such suitable solvents may, for example, be selected from
the group consisting of alcohols different from R.sup.2--OH as
defined herein, ethers, ketones, aromatic hydrocarbons and any
mixture of any of these. Suitable ethers may have a linear or a
cyclic structure and may for example be selected from the group
consisting of diethylether, tetrahydrofuran (THF), butyl phenyl
ether, methyl ethyl ether and 4-methylanisole. Suitable ketones may
for example be selected from the group consisting of acetone,
2-heptanone and cyclohexanone. Suitable aromatic hydrocarbons may
for example be selected from the group consisting of toluene,
mesitylene, o-xylene, m-xylene, p-xylene, cyclohexylbenzene and
halogenated aromatic hydrocarbons. Examples of such halogenated
aromatic hydrocarbons are chlorobenzene, dichlorobenzene and
trichlorobenzene as well as any mixture of any of these.
[0148] Preferably the compound of formula (I) is present in (or
expressed differently, is initially added to) the formulation or
solution in from 0.01 wt % to 10 wt %, preferably from 0.01 wt % to
5 wt %, and most preferably from 0.05 wt % to 2 wt %, with wt %
being relative to the total weight of the formulation or
solution.
[0149] The metal or metal oxide may be applied to the substrate by
any of the conventional methods. The methods may for example be
selected from vacuum deposition, vapor deposition and liquid
coating. Exemplary deposition methods include physical vapor
deposition (PVD), chemical vapor deposition (CVD), sublimation or
liquid coating methods. Such methods form part of the general
knowledge in the field and are well known to the skilled
person.
[0150] Before the SAM treatment, i.e. the formation of the
self-assembled monolayer, the metal or metal oxide surface is
preferably subjected to a washing step. A preferred washing step
comprises an acidic washing with a acid or a blend of acids, said
acids being organic or inorganic acids. Examples of suitable acids
are acetic acid, citric acid or hydrochloric acid. Alternatively
the metal or metal oxide surface may be subjected to a plasma
treatment step.
[0151] In a preferred embodiment, the washing step and the SAM
treatment are combined into a single step. For example, this
combined step may be carried out by applying a formulation in
accordance with the present invention to the metal or metal oxide
surface, said formulation comprising a precursor compound as
defined above and an acid as defined above.
[0152] Alternatively the washing step and the SAM treatment may be
carried out sequentially in two separate steps.
[0153] The soaking time, i.e. the time during which the formulation
is applied to the metal or metal oxide surface, is preferably at
least 5 s and at most 72 h.
[0154] In the preparation of the other layers of the electronic
devices, preferably the organic electronic devices, of the present
invention standard methods may be used to deposit the various
layers and materials as described above.
[0155] Preferably the deposition of individual functional layers in
the preparation of the present electronic devices, such as for
example the organic semiconducting layer or the insulator layer, is
carried out using solution processing techniques. This can be done
for example by applying a formulation, preferably a solution,
comprising the organic semiconducting material or the dielectric
material and further comprising one or more organic solvents, onto
the previously deposited layer, followed by evaporation of the
solvent(s). Preferred deposition techniques include, without
limitation, dip coating, spin coating, ink jet printing,
letter-press printing, screen printing, doctor blade coating,
roller printing, reverse-roller printing, offset lithography
printing, flexographic printing, web printing, spray coating, brush
coating, or pad printing. Very preferred solution deposition
techniques are spin coating, flexographic printing and inkjet
printing.
[0156] In an OFET device according to the present invention, the
dielectric material for the gate insulator layer is preferably an
organic material. It is preferred that the dielectric layer is
solution coated which allows ambient processing, but could also be
deposited by various vacuum deposition techniques. When the
dielectric is being patterned, it may perform the function of
interlayer insulation or act as gate insulator for an OFET.
Preferred deposition techniques include, without limitation, dip
coating, spin coating, ink jet printing, letter-press printing,
screen printing, doctor blade coating, roller printing,
reverse-roller printing, offset lithography printing, flexographic
printing, web printing, spray coating, brush coating or pad
printing. Ink-jet printing is particularly preferred as it allows
high resolution layers and devices to be prepared. Optionally, the
dielectric material could be cross-linked or cured to achieve
better resistance to solvents and/or structural integrity and/or to
improve patterning (photolithography). Preferred gate insulators
are those that provide a low permittivity interface to the organic
semiconductor.
[0157] Suitable solvents are selected from solvents including but
not limited to hydrocarbon solvents, aromatic solvents,
cycloaliphatic cyclic ethers, cyclic ethers, acetates, esters,
lactones, ketones, amides, cyclic carbonates or multi-component
mixtures of the above. Examples of preferred solvents include
cyclohexanone, mesitylene, xylene, 2-heptanone, toluene,
tetrahydrofuran, MEK (methyl ethyl ketone), MAK (2-heptanone),
cyclohexanone, 4-methylanisole, butyl-phenyl ether and
cyclohexylbenzene, very preferably MAK, butyl phenyl ether or
cyclohexylbenzene.
[0158] The total concentration of the respective functional
material (organic semiconducting material or gate dielectric
material) in the formulation is preferably from 0.1 to 30 wt %,
preferably from 0.1 to 5 wt %, relative to the total weight of the
formulation (i.e. functional material(s) and solvent(s)). In
particular organic ketone solvents with a high boiling point are
advantageous for use in solutions for inkjet and flexographic
printing.
[0159] When spin coating is used as deposition method, the OSC or
dielectric material is spun for example between 1000 and 2000 rpm
for a period of for example 30 seconds to give a layer with a
preferred layer thickness between about 100 nm and about 2000 nm
for the dielectric and about 5 nm to about 300 nm for the
semiconductor. After spin coating, the film can be heated at an
elevated temperature to remove all residual volatile solvents.
[0160] Optionally the dielectric material layer is annealed after
exposure to radiation, for example at a temperature from 70.degree.
C. to 130.degree. C., for example for a period of from 1 to 30
minutes, preferably from 1 to 10 minutes. The annealing step at
elevated temperature can be used to complete the cross-linking
reaction that was induced by the exposure of the cross-linkable
groups of the dielectric material to photoradiation.
[0161] All process steps described above and below can be carried
out using known techniques and standard equipment which are
described in prior art and are well-known to the skilled person.
For example, in the photoirradiation step a commercially available
UV lamp and photomask can be used, and the annealing step can be
carried out in an oven or on a hot plate.
[0162] Following the deposition of the self-assembled monolayer,
preferably a washing step or a drying step or both are
performed.
[0163] For the organic electronic device being a top gate OFET,
following step (c), said process may additionally comprise the
following steps, preferably in such sequence, of [0164] (d)
depositing as gate insulator layer a dielectric material as defined
herein onto the organic semiconducting layer; [0165] (e) depositing
a gate electrode onto the gate insulator layer; and [0166] (f)
optionally depositing a passivation layer onto the gate
electrode.
[0167] For the organic electronic device being a bottom gate OFET,
before step (a), the process may further comprise the steps of
[0168] (o) depositing a gate electrode onto a substrate; and [0169]
(o') depositing as gate insulator layer a dielectric material onto
the gate electrode.
[0170] Optionally, following step (d), the process may further
comprise the step of [0171] (d) depositing a passivation layer onto
the organic semiconducting layer.
[0172] Further layers may be deposited by standard methods, which
are well known in the industry. Liquid coating of devices is more
desirable than vacuum deposition techniques. Solution deposition
methods are especially preferred. Preferred deposition techniques
include, without limitation, dip coating, spin coating, inkjet
printing, nozzle printing, letter-press printing, screen printing,
gravure printing, doctor blade coating, roller printing,
reverse-roller printing, offset lithography printing, dry offset
lithography printing, flexographic printing, web printing, spray
coating, curtain coating, brush coating, slot dye coating or pad
printing.
[0173] Preferably the gate insulator layer is deposited, e.g. by
spin-coating, doctor blading, wire bar coating, spray or dip
coating or other known methods, from a formulation comprising an
insulator material and one or more solvents with one or more fluoro
atoms (fluorosolvents), preferably a perfluorosolvent. A suitable
perfluorosolvent is e.g. FC75.RTM. (available from Acros, catalogue
number 12380). Other suitable fluoropolymers and fluorosolvents are
known in prior art, like for example the perfluoropolymers Teflon
AF.RTM. 1600 or 2400 (from DuPont) or Fluoropel.RTM. (from Cytonix)
or the perfluorosolvent FC 43.RTM. (Acros, No. 12377).
EXAMPLES
[0174] The advantages of the present application are illustrated by
the following non-limiting examples.
[0175] If not otherwise mentioned all solvents, salts, organic
semiconducting materials etc. were obtained from commercial
sources, such as for example SigmaAldrich or Merck KGaA, Darmstadt,
Germany.
[0176] It is noted that F.sub.5C.sub.6--SiCl.sub.3 is sensitive to
hydrolysis and therefore is best stored in an environment free of
humidity or residual water in solvents.
[0177] The electrical characterization of the transistor devices
was carried out in ambient air atmosphere using computer controlled
Agilent 4155C Semiconductor Parameter Analyser. Charge carrier
mobility in the saturation regime (.mu..sub.sat) was calculated for
the compound. Field-effect mobility was calculated in the
saturation regime (V.sub.d>(V.sub.g-V.sub.0)) using equation
(eq. 1):
( d .times. I d s .times. a .times. t dV g ) V d = W .times. C i L
.times. .mu. s .times. a .times. t .function. ( V g - V 0 ) ( eq .
.times. 1 ) ##EQU00001##
where W is the channel width, L the channel length, C.sub.i the
capacitance of insulating layer, V.sub.g the gate voltage, V.sub.0
the turn-on voltage, and .mu..sub.sat is the charge carrier
mobility in the saturation regime. Turn-on voltage (V.sub.0) was
determined as the onset of source-drain current.
Example 1--Work Function Measurement
[0178] Work functions were determined using a Kelvin Probe for
electrodes with and without self-assembled monolayer (SAM), wherein
the self-assembled monolayer was prepared by immersing the
respective electrodes on a glass substrate into a solution of
F.sub.5C.sub.6--SiCl.sub.3 in iso-propanol (.sup.iPr--OH), such
solution thus--without wishing to be bound by theory--probably
predominantly comprising F.sub.5C.sub.6--Si(O-.sup.iPr).sub.3 as
active species. The respective results are indicated in Table
1.
TABLE-US-00001 TABLE 1 Work function Sample [eV] ITO without SAM
4.8 Molybdenum without SAM 4.9 ITO with SAM 5.4-5.6 (estimated)
Molybdenum with SAM 5.5-5.7
Example 2--Device Preparation
[0179] Indium tin oxide (ITO) electrodes on glass were placed in a
spin coater and brought for one minute into contact with a solution
of F.sub.5C.sub.6--SiCl.sub.3 in iso-propanol (.sup.iPr--OH), such
solution thus--without wishing to be bound by theory--probably
predominantly comprising F.sub.5C.sub.6--Si(O--.sup.iPr).sub.3 as
active species, thereby forming the self-assembled monolayer.
Excess solution was spun off, following by rinsing with
iso-propanol. Onto the resulting self-assembled monolayer was then
deposited a layer of an organic semiconducting material comprising
derivatives of indacenodithiophene and benzothiadiazole.
[0180] Respective mobilities are indicated in Table 2 below.
Example 3--Device Preparation (Comparative)
[0181] The preparation of Example 2 was repeated with the
difference that for the preparation of the self-assembled monolayer
para-chlorobenzene phosphate (see formula (III) below) in
iso-propanol, instead of the F.sub.5C.sub.6--SiCl.sub.3 in
iso-propanol, was used.
##STR00040##
[0182] Respective mobilities are indicated in Table 2 below.
TABLE-US-00002 TABLE 2 Linear mobility Saturated mobility On off
[cm.sup.2V.sup.-1s.sup.-1] [cm.sup.2V.sup.-1s.sup.-1] ratio Example
2 1.06 1.72 10.sup.6 Example 3 (comp.) 0.38 0.54 10.sup.6
* * * * *