U.S. patent application number 17/257377 was filed with the patent office on 2021-09-02 for composition comprising semiconducting light emitting nanoparticles.
This patent application is currently assigned to MERCK PATENT GMBH. The applicant listed for this patent is MERCK PATENT GMBH. Invention is credited to Denis GLOZMAN, Yuki HIRAYAMA, Christian-Hubertus KUECHENTHAL, Ehud SHAVIV, Teruaki SUZUKI.
Application Number | 20210269657 17/257377 |
Document ID | / |
Family ID | 1000005635897 |
Filed Date | 2021-09-02 |
United States Patent
Application |
20210269657 |
Kind Code |
A1 |
GLOZMAN; Denis ; et
al. |
September 2, 2021 |
COMPOSITION COMPRISING SEMICONDUCTING LIGHT EMITTING
NANOPARTICLES
Abstract
The present invention relates to a composition and to a method
of manufacturing a composition.
Inventors: |
GLOZMAN; Denis; (Modiin,
IL) ; SHAVIV; Ehud; (Modiin, IL) ; HIRAYAMA;
Yuki; (Tokyo, JP) ; SUZUKI; Teruaki;
(Kanagawa, JP) ; KUECHENTHAL; Christian-Hubertus;
(Jerusalem, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MERCK PATENT GMBH |
DARMSTADT |
|
DE |
|
|
Assignee: |
MERCK PATENT GMBH
DARMSTADT
DE
|
Family ID: |
1000005635897 |
Appl. No.: |
17/257377 |
Filed: |
July 2, 2019 |
PCT Filed: |
July 2, 2019 |
PCT NO: |
PCT/EP2019/067670 |
371 Date: |
December 31, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09K 11/883 20130101;
C09K 11/02 20130101; C09D 5/22 20130101; C09K 11/0883 20130101;
C09D 7/63 20180101 |
International
Class: |
C09D 5/22 20060101
C09D005/22; C09K 11/88 20060101 C09K011/88; C09K 11/08 20060101
C09K011/08; C09K 11/02 20060101 C09K011/02; C09D 7/63 20060101
C09D007/63 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 5, 2018 |
EP |
18182015.0 |
Claims
1. A composition comprising at least: i) a semiconducting light
emitting nanoparticle; ii) a macromolecular compound comprising at
least an anchoring group; iii) an organic additive.
2. The composition of claim 1, wherein the organic additive is
defined by formula (Ia) or (Ib) M-(X--Y).sub.2 (Ia); X--Y (Ib),
wherein M is a divalent metal ion, X is a hydrocarbon chain, and Y
is a functional group.
3. The composition according to claim 2, wherein at least one of
the following applies: a) M is selected from the group consisting
of Zn.sup.2+, Mg.sup.2+ and Cd.sup.2+; b) Y is selected from the
group consisting of carboxylate, carbamate, xanthate, phosphonate,
phosphate, thiolate; or a combination of two or more thereof.
4. The composition of claim 1, wherein the organic additive is
defined by formula (II), ##STR00003## wherein M is selected from
the group consisting of Zn.sup.2+, Mg.sup.2+ and Cd.sup.2+; R.sub.1
and R.sub.2 can be same or different, linear or branched, and each
R.sub.1, R.sub.2 is selected from the group consisting of an alkyl
having a chain of 1 to 16 carbons atoms or an alkenyl group having
a chain of 1 to 15 carbon atoms.
5. The composition of claim 1, wherein the organic additive
comprises a Zinc carboxylate.
6. The composition of claim 1, wherein the at least one anchoring
group of the macromolecular compound is ionic.
7. The composition of claim 1, wherein the at least one anchoring
group of the macromolecular compound is selected from the group
consisting of phosphine group, phosphine oxide group, phosphate
group, phosphonate group, thiol group, tertiary amine, carboxyl
group, hetero cyclic group, silane group, sulfonic acid, hydroxyl
group; or a combination of two or more thereof.
8. The composition of claim 1, wherein the macromolecular compound
has a number average molecular weight of at least 1,000 g/mol.
9. The composition of claim 1, wherein the macromolecular compound
is based on a copolymer.
10. The composition of claim 9, wherein the copolymer is selected
from the group consisting of graft copolymer, block copolymer,
alternating copolymer, random copolymer.
11. The composition of claim 1, wherein the macromolecular compound
comprises at least one acrylate.
12. The composition of claim 1, wherein the composition further
comprises at least an organic phase.
13. The composition of claim 1, wherein the composition further
comprises a matrix polymer.
14. The composition of claim 13, wherein the matrix polymer is
selected from an acrylate, an epoxy resin, a polyurethane and a
polysiloxane.
15. A method of manufacturing a composition with improved quantum
yield, comprising at least these steps: a/ Manufacturing a mixture
by at least these steps: 1/ Providing a semiconducting light
emitting nanoparticle, 2/ Adding a macromolecular compound
comprising at least an anchoring group; 3/ Adding an organic
additive which forms the composition according to claim 1; b/
Subjecting the mixture from step (a) to irradiation with light of a
wavelength selected from a range of 300 to 600 nm having an
intensity in the range from 0.025 to 1 W/cm.sup.2 to obtain the
composition.
16. A method of manufacturing a layered composite comprising at
least these steps: (A) Manufacturing a mixture by at least these
steps: (1) Providing a semiconducting light emitting nanoparticle;
(2) Adding a macromolecular compound comprising at least an
anchoring group; (3) Adding an organic additive which forms the
composition according to claim 1; (B) Applying the mixture to a
substrate in order to form a layer; and (C) Drying the layer on the
substrate.
17. The method of claim 16, wherein the at least one of the
following features applies: a/ The mixture obtained from step (A)
is irradiated with light prior to step (B); b/ The layer on the
substrate is irradiated with light in a step (D) following to step
(C); wherein the light has a wavelength selected from a range of
300 to 600 nm having an intensity in the range from 0.025 to 1
W/cm.sup.2 to obtain the composition.
18. A layered composite obtainable or obtained by the method of
claim 16.
19. A layered composite comprising: .alpha.) a substrate; .beta.)
at least a layer comprising a. a semiconducting light emitting
nanoparticle; b. a macromolecular compound comprising at least an
anchoring group; and c. an organic additive wherein thus the layer
comprises the composition according to claim 1.
20. An optical device comprising a layered composite according to
claim 18.
21. A method to improve the emission efficiency of a semiconducting
light emitting nanoparticle, comprising adding an organic additive
to said semiconducting light emitting nanoparticle.
22. A method to improve the quantum yield of a composition
comprising a semiconducting light emitting nanoparticle and an
organic additive, comprising irradiating said composition with a
light of a wavelength in the range from 300 to 600 nm having an
intensity in the range from 0.025 to 1 W/cm2.
Description
[0001] The present invention relates to a composition comprising at
least these components: i) a semiconducting light emitting
nanoparticle; ii) a macromolecular compound comprising at least an
anchoring group; and iii) an organic additive. The invention
further relates to a method of manufacturing a composition with
improved solubility/dispersion properties while
maintaining/improving the original quantum yield of the
nanomaterials, a method of manufacturing a solution of the
semiconducting light emitting nanoparticle in organic medium that
can be used for producing a layered composite comprising at least
these steps: (A) manufacturing a mixture by at least these steps:
i) providing a semiconducting light emitting nanoparticle; ii)
adding a macromolecular compound comprising an anchoring group;
iii) adding an organic additive; (B) applying the mixture to a
substrate in order to form a layer; and (C) drying the layer on the
substrate. The invention further relates to a layered composite
obtainable by said method and a layered composite comprising:
.alpha.) a substrate; .beta.) at least a layer comprising: a. a
semiconducting light emitting nanoparticle; b. a macromolecular
compound comprising an anchoring group; and c. an organic additive.
The invention relates also to a use of an organic additive to
improve the efficiency of the emission of light.
[0002] Semiconducting light emitting nanoparticles, also referred
to as quantum materials, such as quantum dots, quantum rods,
tetrapods and the like are of great interest as color converter
materials in LEDs and displays due to their narrow fluorescence
emission. Using light emitting quantum material for applications
such as down conversion layers in LCDs, color filters and color
converters directly on top of LEDs requires the Semiconducting
nanocrystals to be incorporated into a thin layer that would
provide protection for the nanocrystals. A polymer film which
contains a quantum material is one way to achieve these desired
thin layers. Various polymers have been used for this purpose, such
as acrylate, siloxanes, silazanes, epoxies, silicones, and so on.
In particular, acrylates are abundantly used for backlight film
applications.
[0003] Incorporation of a quantum material like quantum dots into
this kind of layers causes a drop in their emission quantum Yield
(QY). This is caused by aggregation of the quantum materials in the
solid polymer film and due to chemical processes, which affect the
organic molecules attached to the surface of the quantum material
(known as ligands) and cause detachment of the ligands from the
quantum materials surface occurs.
[0004] In a more recent development, InP based nanocrystals became
the leading candidates for cadmium free quantum material based
display materials. Surface treatment methods could be a pathway for
gaining solubility in different solvents and matrices and improving
the quantum yield of such materials. The use of dispersants is one
technique to render quantum materials soluble in solvents that are
not per se suitable for the quantum materials, for example when
dispersing a non-polar quantum material in polar solvents. Many
commercially available wetting and dispersing agents are known for
this purpose, but these agents are not "tailor made". Thus, their
compatibility to different sorts of quantum material vary and often
has negative influence on the stability of the dispersion of
quantum material and on the emissive quantum yield.
[0005] Accordingly, and despite all efforts of the past it is still
an object to provide an improved dispersion of a semiconducting
light emitting nanoparticle, preferably a quantum material in a per
se incompatible medium and to preserve the achievable emissive
quantum yield of the quantum material.
[0006] In general terms, it is an object of the present invention
to at least partly overcome at least one of the disadvantages that
are known from the prior art.
[0007] Another object is to provide a composition comprising a
semiconducting light emitting nanoparticle, preferably a quantum
material for application on substrates which can be used to
manufacture layers with said semiconducting light emitting
nanoparticle, wherein the quantum yield of the semiconducting light
emitting nanoparticle, preferably a quantum material is preserved,
and not reduced as is in those known in the art.
[0008] Another object of the invention is to provide semiconducting
light emitting nanoparticle, preferably a quantum material in a
composition, wherein the quantum material is more efficient and/or
exhibit higher output than those known in the art.
[0009] Another object of the invention is to provide a
semiconducting light emitting nanoparticle as part of a
composition, wherein the composition exhibits a similar quantum
yield and/or exhibits a similar output like the quantum material in
the medium without the additive.
[0010] Another object of the invention is to provide a
semiconducting light emitting nanoparticle as part of a
composition, wherein the composition exhibits a higher quantum
yield and/or exhibits a higher output than the quantum material in
the medium without the additive.
[0011] Another object of the invention is to provide a
semiconducting light emitting nanoparticle, preferably a quantum
material in a composition with high stability and high quantum
yield over the lifetime of the quantum material.
[0012] Another object of the invention is to provide means,
auxiliaries or methods to improve the quantum yield of a
semiconducting light emitting nanoparticle containing solution.
[0013] A contribution to the solution of at least one of the above
objects is provided by the subject-matter of the category-forming
embodiments. The dependent sub-embodiments of the category-forming
embodiments represent preferred embodiments of the invention, the
subject-matter of which also makes a contribution to solving at
least one of the objects mentioned above.
Definitions
[0014] The term "in the range from x to y" is understood in the
present context to comprise all values between the number x and y,
and the limit forming numbers x and y. For example, the term "in
the range from 2 to 13" comprises the numbers 2, 13 and all in
between.
[0015] The term "inorganic" in the present context describes any
material not containing any carbon atoms which are bound to other
carbon atoms and/or hydrogen atoms. Inorganic material, however,
can comprise one or more compounds, which contain carbon atoms
ionically bound to other atoms such as carbon monoxide, carbon
dioxide, carbonates, cyanides, cyanates, carbides, and
thiocyanates.
[0016] The term "transparent" means in the present context that at
least around 60% of incident light pass through a sample of a
thickness of 5 .mu.m and at a reference wavelength of 450 nm.
Preferably, more than 70%, or more than 75%, or more than 80% of
incident light pass through the sample.
[0017] The term "macromolecular compound" can be any kind of
polymer or polymer blend which is known and appears useful to be
employed in the present composition to a skilled person. An example
of a suited macromolecular compound is an acrylate polymer, or a
block copolymer comprising an acrylate.
[0018] A liquid phase is a composition of one or more components
which is liquid at room temperature (20.degree. C.). This means
that a maximum of 1 wt.-% of the composition does not pass a filter
with pores having 1 .mu.m.
[0019] Although the term "nano-sized" is clear for every skilled
person working in the technological are to which the present
invention belongs, it should be expressed that nano-sized has the
meaning of an average particle diameter in the range of 0.1 nm to
999 nm, preferably 1 nm to 150 nm, more preferably 3 nm to 50
nm.
[0020] According to the present invention, the term "semiconductor"
means a material that has electrical conductivity to a degree
between that of a conductor (such as copper) and that of an
insulator (such as glass) at room temperature. Preferably, a
semiconductor is a material whose electrical conductivity increases
with the temperature.
[0021] Thus, according to the present invention, semiconducting
light emitting nanoparticle is taken to mean that the light
emitting material which size is in between 0.1 nm and 999 nm,
preferably 1 nm to 150 nm, more preferably 3 nm to 50 nm, having
electrical conductivity to a degree between that of a conductor
(such as copper) and that of an insulator (such as glass) at room
temperature, preferably, a semiconductor is a material whose
electrical conductivity increases with the temperature, and the
size is in between 0.1 nm and 999 nm, preferably 0.5 nm to 150 nm,
more preferably 1 nm to 50 nm.
[0022] According to the present invention, the term "size" means
the average diameter of the longest axis of the semiconducting
nano-sized light emitting particles.
[0023] The average diameter of the semiconducting nano-sized light
emitting particles are calculated based on 100 semiconducting light
emitting nanoparticles in a TEM image created by a Tecnai G2 Spirit
Twin T-12 Transmission Electron Microscope.
[0024] A liquid organic phase is a liquid phase of organic
compounds. Organic compounds are compounds that are composed of one
or more carbon-carbon and/or carbon-hydrogen bonds.
[0025] A "Polymer" is a material which is built by one or more
repeat units.
[0026] Chemical compounds can be followed by an expression in
brackets. In this event, the bracket mentions a trademark for
illustrative purposes, under which the chemical compound can be
purchased.
DETAILED DESCRIPTION OF THE INVENTION
[0027] A first aspect of the invention is a composition comprising
at least these components:
[0028] i) a semiconducting light emitting nanoparticle;
[0029] ii) a macromolecular compound comprising at least an
anchoring group;
[0030] iii) an organic additive; which is preferably not a
polymer;
[0031] iv) optionally, a liquid organic phase.
[0032] The composition can be of any kind known to a skilled
person. The composition is a suspension, so it comprises liquid and
solid constituents. An example of a liquid constituent is the
organic phase. The quantum material is an example of solid
constituents. Each one of the further constituents of the
composition can be of solid or liquid state at room temperature
(20.degree. C.). Each one of the further constituents solid at room
temperature can be present as a solid in the composition, or at
least partially dissolve or form a gel through the liquid
constituents of the composition.
[0033] The semiconducting light emitting nanoparticle as a
constituent of the composition can be any kind of semiconducting
light emitting nanoparticles known to and considered potentially
useful by the skilled person. A semiconducting light emitting
nanoparticle in the context of the present invention can be of any
shape known shape for a quantum material, yet is preferably
selected from a rod, a dot, a platelet, a flower and a wire.
Further, the quantum material can comprise a combination of two or
more of the aforementioned shapes.
[0034] According to the present invention, the term
"semiconducting" describes a material whose electronic structure
comprises a conduction band, a valence band, and a band gap between
the two. The band gap of a semiconducting material is usually
larger than zero and less than 4 eV at a temperature of 300K.
[0035] So, a "semiconducting" material has electrical conductivity
to a degree between that of a conductor (such as copper) and that
of an insulator (such as glass) at room temperature. Preferably, a
semiconducting material has an electrical conductivity increases
with the temperature.
[0036] The term "nanoparticles" means particles which have a size
in between 0.1 nm and 999 nm, preferably 0.5 nm to 150 nm, more
preferably 1 nm to 50 nm. The term "size" in the present context
means the average diameter of the longest axis which can be
established through the particles referred to. The size of these
nanoparticles refers to the dimension of the inorganic,
semiconducting nanoparticle, not considering the dimensions of
possibly present ligands on the surface of the inorganic
semiconducting nanoparticle, or other surface modification applied
thereto. The average diameter of a certain particle is calculated
based on statistics measured by Transmission Electron Microscope
(TEM).
[0037] The term "light emitting" refers to the property of a
material or object to emit light at least of a wavelength from 350
nm to 1000 nm upon an external optical excitation such as an
incident beam of light of a specific wavelength or a specific
wavelength range.
[0038] The term "semiconducting light emitting nanoparticle" in the
present context refers to a light emitting material which is in
accordance with the definition of "semiconducting" and has a
nanoparticle size is in between 0.1 nm and 999 nm, preferably 1 nm
to 150 nm, more preferably 1 nm to 50 nm.
[0039] In a preferred embodiment of the present invention, the
semiconducting light emitting nanoparticle of the present invention
is a quantum sized material.
[0040] According to the present invention, the term "quantum sized"
means the size of the semiconducting material itself without
ligands or another surface modification, which can show the quantum
confinement effect, like described in, for example,
ISBN:978-3-662-44822-9.
[0041] The quantum material can emit light. The quantum material
can emit tunable, sharp and light in the VIS and IR range. VIS
refers to light of a wavelength from 400 to 700 nm; IR refers to
light of a wavelength above 700 nm up to about 1 mm.
[0042] In a preferred embodiment of the present invention, the
quantum material is selected from the group consisting of II-VI,
III-V, and IV-VI semiconductors, and a combination of two or more
thereof.
[0043] More preferably, the quantum material is selected from the
group consisting of Cds, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, GaAs,
GaP, GaAs, GaSb, HgS, HgSe, HgSe, HgTe, InAs, InP, InPZn, InPZnS,
InSb, AlAs, AlP, AlSb, Cu.sub.2S, Cu.sub.2Se, CuInS.sub.2,
CuInSe.sub.2, Cu.sub.2(ZnSn)S.sub.4, Cu.sub.2(InGa)S.sub.4,
TiO.sub.2, InGaP, ZnSeS, alloys, and a combination of two or more
thereof.
[0044] For example, for red emission use CdSe/CdS, CdSeS/CdZnS,
CdSeS/CdS/ZnS, ZnSe/CdS, CdSe/ZnS, InP/ZnS, InP/ZnSe, InP/ZnSe/ZnS,
InPZn/ZnS, InPZn/ZnSe/ZnS dots or rods, ZnSe/CdS, ZnSe/ZnS and a
combination of two or more thereof.
[0045] For example, for green emission use CdSe/CdS, CdSeS/CdZnS,
CdSeS/CdS/ZnS, ZnSe/CdS, CdSe/ZnS, InP/ZnS, InP/ZnSe, InP/ZnSe/ZnS,
InPZn/ZnS, InPZn/ZnSe/ZnS, ZnSe/CdS, ZnSe/ZnS and a combination of
two or more thereof.
[0046] For example, for blue emission use, e.g., ZnSe, ZnS,
ZnSe/ZnS, and a combination of two or more thereof.
[0047] As a quantum material, publicly available quantum material,
for examples, CdSeS/ZnS alloyed quantum materials product number
753793, 753777, 753785, 753807, 753750, 753742, 753769, 753866,
InP/ZnS quantum materials product number 776769, 776750, 776793,
776777, 776785, PbS core-type quantum materials product number
747017, 747025, 747076, 747084, or CdSe/ZnS alloyed quantum
materials product number 754226, 748021, 694592, 694657, 694649,
694630, 694622 from Sigma-Aldrich, can be used preferably as
desired.
[0048] In some embodiments, the semiconductor nanoparticle can be
selected from an anisotropic shaped structure, for example quantum
rod material to realize better out-coupling effect (for example ACS
Nano, 2016, 10 (6), pp 5769-5781).
[0049] Examples of quantum rod material have been described in, for
example, the international patent application laid-open No.
WO2010/095140A.
[0050] In a preferred embodiment of the invention, the length of
the overall structures of the quantum material, such as a quantum
rod material/or the quantum material, is from 1 nm to 500 nm,
preferably, from 1 nm to 160 nm, even more preferably, from 1 nm to
20 nm, most preferably, it is from 5 nm to 15 nm.
[0051] A macromolecular compound having at least one anchoring
group, sometimes also referred to as a dispersing and wetting
agent, can be attached onto the surface of the ligand of the
quantum material or directly attached onto the surface of the
quantum material, partially or fully by using a ligand exchange
process. Preferably, the quantum material can comprise a surface
ligand. The surface of the quantum material can be over coated with
one or more kinds of surface ligands. Without wishing to be bound
by theory it is believed that such a surface ligand may lead to
disperse the quantum material in an organic solvent more easily.
The macromolecular compound can by any kind of macromolecular
compound that is known to the skilled person and appears suited in
the present invention.
[0052] According to the present invention, the composition
comprises a macromolecular compound, wherein the macromolecular
compound comprises at least one anchoring group. In a preferred
embodiment of the invention, the at least one anchoring group,
preferably two or all anchoring groups of the macromolecular
compound is/are ionic. The macromolecular compound comprising the
at least one anchoring group can form a salt in the presence of
counter-ions. The macromolecular compound preferable forms a
cationic or an anionic species. The counter-ion for a cationic
species is an anionic counter-ion, the counter-ion for an anionic
species is a cationic counter-ion. One macromolecular compound may
have more than one counter-ions of a species.
[0053] In a preferred embodiment of the present invention, the at
least one anchoring group of the macromolecular compound is anionic
and selected from the group consisting of phosphine group,
phosphine oxide group, phosphate group, phosphonate group, thiol
group, tertiary amine, carboxyl group, hetero cyclic group, silane
group, sulfonic acid, hydroxyl group.
[0054] In a further preferred embodiment of the present invention,
90% or more of all anchoring groups of the macromolecular compound
are selected form group above, the % based on the absolute number
of anchoring groups. Further preferred, 90% or more of all
anchoring groups are identical, the % based on the absolute number
of anchoring groups.
[0055] More preferably, the anchoring group of the macromolecular
compound is a quaternary ammonium salt represented by following
chemical formula (I),
--N.sup.+R.sub.1R.sub.2R.sub.3X.sup.- (I)
[0056] wherein R.sub.1 is a hydrogen atom, alkyl group having 1 to
30 carbon atoms, or an aryl group having 1 to 30 carbon atoms;
R.sub.2 is a hydrogen atom, alkyl group having 1 to 30 carbon
atoms, or an aryl group having 1 to 30 carbon atoms; R.sub.3 is a
hydrogen atom, alkyl group having 1 to 30 carbon atoms, or an aryl
group having 1 to 30 carbon atoms; and wherein R.sub.1, R.sub.2 and
R.sub.3 can be same or different of each other; and wherein X is an
anion selected from the group consisting of F, Cl, Br, I,
phosphate, carboxylate, sulfonate, and phosphonate.
[0057] Even more preferably, R.sub.1 is a hydrogen atom or an alkyl
group having 1 to 30 carbon atoms; R.sub.2 is a hydrogen atom or an
alkyl group having 1 to 30 carbon atoms; R.sub.3 is a hydrogen atom
or an alkyl group having 1 to 30 carbon atoms; R.sub.1, R.sub.2 and
R.sub.3 can be same or different of each other.
[0058] In a preferred embodiment of the present invention, the
macromolecular compound is at least in part attached directly onto
the surface of the quantum material. By using ligand exchange
method, described in for example, Thomas Nann, Chem. Commun., 2005,
1735-1736, DOI: 10.1039/b-414807j, the macromolecular compound can
be introduced onto the surface of the quantum material.
[0059] According to the present invention, the weight-average
molecular weight of the macromolecular compound is not particularly
limited. It can be of any number which appears suitable to a
skilled person. Preferably, the weight-average molecular weight is
in the range from 1,000 to 100,000 g/mol. More preferably, it is in
the range from 2,000 to 50,000 g/mol, or from 5,000 to 30,000
g/mol. Macromolecular compounds of the preferred weight range were
found to contribute to an improved dispersivity and film strength.
The weight-average molecular weight (Mw) is determined by means of
GPC (=gel permeation chromatography) against polystyrene
calibration standards, solvent THE.
[0060] In a further preferred embodiment of the invention, the
macromolecular compound is based on a at least one copolymer.
[0061] In a further preferred embodiment of the invention, the
copolymer is selected from the group consisting of graft copolymer,
block copolymer, alternating copolymer, random copolymer,
preferably it is a block copolymer.
[0062] The macromolecular compound of a further preferred
embodiment is selected from the group consisting of Disperbyk-100
series, such as Disperbyk-180, and Disperbyk-2000 series, such as
Disperbyk-2000, 2001, 2009 (all available from BYK.com).
[0063] The organic additive can be any which is known to the
skilled person and appears to be suited in the present invention.
The organic additive can comprise metal or and may not comprise any
metal species. A metal species in the present context can be a
metal cation or elemental metal, which can be presented as is, or
as part of a complex. Preferably, the organic additive is not a
polymer/macromolecular.
[0064] In a preferred embodiment of the invention, the organic
additive is defined by formula (Ia) or (Ib)
M-(X--Y).sub.2 (Ia);
X--Y (Ib)
[0065] wherein
[0066] M is a divalent metal ion,
[0067] X is a hydrocarbon chain, and
[0068] Y is a functional group.
[0069] In a further preferred embodiment of the invention, the
organic additive is defined by formula (Ia) or (Ib) and, at least
one of the following applies:
[0070] a) M is selected from the group consisting of Zn.sup.2+,
Mg.sup.2+ and Cd.sup.2+;
[0071] b) Y is selected from the group consisting of carboxylate,
carbamate, xanthate, phosphonate, phosphate, thiolate.
[0072] A further preferred embodiment is a combination of two or
more organic additives, where one of these features applies: a
combination of a) and b), or a combination of two or more of a)
with one b), or a combination of two or more of b) with one a), or
a combination of two or more of a) and two or more of b).
[0073] In a further preferred embodiment of the invention, the
organic additive is defined by formula (II),
##STR00001##
[0074] wherein
[0075] M is selected from the group consisting of Zn.sup.2+,
Mg.sup.2+ and Cd.sup.2+;
[0076] R.sub.1 and R.sub.2 can be same or different, linear or
branched, and each R.sub.1, R.sub.2 is selected from the group
consisting of an alkyl having a chain of 1 to 16 carbons atoms or
an alkenyl group having a chain of 1 to 15 carbon atoms; preferably
1 to 11, or 1 to 6 carbon atoms.
[0077] In a further preferred embodiment of the invention, the
organic additive comprises an element selected from the group
consisting of a Zinc carboxylate, a Cadmium carboxylate and a
Magnesium carboxylate, or a combination of two or more elements
thereof.
[0078] In a further preferred embodiment of the invention, the
organic additive comprises a Zinc carboxylate.
[0079] In a further preferred embodiment of the invention, the
composition further comprises at least a liquid organic phase. In a
further preferred embodiment of the invention, the liquid organic
phase of the composition comprises at least one organic
solvent.
[0080] In a preferred embodiment of the present invention, the
solvent can be selected from the group consisting of ethylene
glycol monoalkyl ethers, such as, ethylene glycol monomethyl ether,
ethylene glycol monoethyl ether, ethylene glycol monopropyl ether,
and ethylene glycol monobutyl ether; diethylene glycol dialkyl
ethers, such as, diethylene glycol dimethyl ether, diethylene
glycol diethyl ether, diethylene glycol dipropyl ether, and
diethylene glycol dibutyl ether; ethylene glycol alkyl ether
acetates, such as, methyl cellosolve acetate and ethyl cellosolve
acetate; propylene glycol alkyl ether acetates, such as, propylene
glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl
ether acetate, and propylene glycol monopropyl ether acetate;
aromatic hydrocarbons, such as, benzene, toluene and xylene;
ketones, such as, methyl ethyl ketone, acetone, methyl amyl ketone,
methyl isobutyl ketone, and cyclohexanone; alcohols, such as,
ethanol, propanol, butanol, hexanol, cyclohexanol, ethylene glycol,
and glycerin; esters, such as, ethyl 3-ethoxypropionate, methyl
3-methoxypropionate and ethyl lactate; and cyclic asters, such as,
.gamma.-butyrolactone. Preferred solvents of the above group are
propylene glycol alkyl ether acetates, such as, propylene glycol
monomethyl ether acetate (hereafter "PGMEA"), propylene glycol
monoethyl ether acetate, or propylene glycol monopropyl ether
acetate can be used.
[0081] In a further preferred embodiment, the liquid organic phase
comprises a combination of two or more of the above organic
solvents. This includes two or more solvents of one of the groups,
or two or more solvents from different of the above groups.
[0082] In a further preferred embodiment of the invention, the
composition further comprises at least one matrix polymer. Any
polymer can be selected as matrix polymer which is known to the
skilled person and appears to be suited to be employed as matrix
for the quantum material of the present invention. Preferred matrix
polymers are those, which are transparent and suited for the
manufacture of optical devices.
[0083] In a further preferred embodiment of the invention, the
matrix polymer has a weight-average molecular weight in the range
from 1,000 to 300,000 g/mol, more preferably from 10,000 to 250,000
g/mol.
[0084] In a further preferred embodiment of the invention, the
matrix polymer has a glass transition temperature (Tg) which is
70.degree. C. or more. Yet more preferred, the glass transition
temperature of the matrix polymer is in the range from 70.degree.
C. to 250.degree. C. The glass transition temperature is measured
according to DIN EN ISO 11357, Teil 1-6 using a Dynamic Scanning
Calorimetry instrument, for example a PerkinElmer DSC-8000.
[0085] In a further preferred embodiment of the invention, the
matrix polymer is selected from an acrylate, an epoxy resin, a
polyurethane and a polysiloxanes.
[0086] A second aspect of the invention is a method of
manufacturing a composition as described with the first aspect and
its embodiments.
[0087] A third aspect of the invention is method of manufacturing a
composition with improved quantum yield, comprising at least these
steps:
[0088] a/ Manufacturing a mixture by at least these steps:
[0089] 1/ Providing a quantum material;
[0090] 2/ Adding a macromolecular compound comprising at least an
anchoring group;
[0091] 3/ Adding an organic additive;
[0092] 4/ optionally adding at least an organic solvent;
[0093] b/ Subjecting the mixture from step a/ to irradiation with
light of a wavelength selected from a range of 300 to 600 nm having
an intensity in the range from 0.025 to 1 W/cm.sup.2 to obtain the
composition.
[0094] The intensity of light is measured at the surface of the
mixture of the light source side.
[0095] Steps 1/ to 4/ can be carried out in individual actions or
by just combining some or all components to the mixture in one
vessel and forming the mixture by stirring the vessel's
content.
[0096] In step 2/, a macromolecular compound comprising at least
one anchoring group is added to the quantum material of step 1/.
The macromolecular compound can be added as a solid, for example as
powder. It can also be dispersed or dissolved in a liquid phase.
The liquid phase can comprise any kind of liquid phase, optionally
comprising one or more of the organic solvents, which is known to
the skilled person and considered useful to have a quantum material
and the macromolecular compound comprising at least one anchoring
group dispersed therein. Reference is made to the section of the
first aspect to the present invention regarding organic solvents
and preferred embodiments. A preferred organic phase for this is
PGMEA.
[0097] In step 3/ an organic additive is added to the combined
liquid phases of step 1/ and 2/. The organic additive can be added
in pure or diluted form.
[0098] Preferably, the organic additive is added pure. Reference is
made to the section related to the organic additive, as described
in the first aspect to the present invention, in particular
regarding a preferred choice of organic additive and further
preferred embodiments.
[0099] In optional step 4/, at least an amount of at least an
organic solvent is added. The organic solvent of this step can be
same or different to any organic solvent present in any of the
liquid phases added in any one of step 1/ to 3/. Reference is made
to the section of the first aspect to the present invention
regarding suited organic solvents and preferred embodiments. A
preferred organic phase for this is PGMEA.
[0100] The mixture of step a/ can be obtained by agitating the
constituents of step 1/ to 3/, and optionally including the
constituent of step 4/. Agitation can be performed individually in
each of the aforementioned steps 1/ through 3/and optionally also
in step 4/. In a preferred embodiment, a liquid phase is provided
under agitation with the quantum material in step 1/, and agitation
is maintained throughout each of the further steps 2/, 3/, and
optionally, 4/. Moreover, intervals of agitation can be implemented
between each of steps 1/ through 3/, and optionally step 4/. This
allows the liquid phase, or a combination of the liquid phase from
step 1/ with one or more further constituents to sit and/or
homogenize prior to adding another constituent.
[0101] Manufacturing of the mixture in step a/ can be operated
under inert conditions, at room temperature as well as elevated
temperature, and/or at standard pressure, elevated or reduced
pressure, all this referred to the conditions in the mixing vessel.
Preferably, step a/ is operated under inert conditions at a
temperature in the range from 0 to 100.degree. C. and ambient
pressure, which is 1 bar (101.3 kPa), based on the absolute scale
(0 kPa=absolute vacuum). Agitation can be achieved by rotating the
mixing vessel or by inserting a rotating mixer into a static mixing
vessel. A preferred mode of operation includes the use of a flask
as static mixing vessel and a stirrer.
[0102] In step b/the mixture from step a/is subjected to
irradiation with light of a wavelength selected from a range of 300
to 600 nm having an intensity in the range from 0.025 to 1
W/cm.sup.2 to obtain the composition.
[0103] It was found that exposing a mixture comprising a quantum
material as described above to light can enhance the quantum yield
of the mixture compared with a mixture of quantum material which is
not treated this way.
[0104] In an embodiment of the invention, the wavelength of the
light is selected in the range of 350-500 nm. The intensity of
light can be same or varying with the wavelength over the
spectrum.
[0105] In another embodiment of the invention, the intensity of the
light is in the range from 0.05 to 0.5 W/cm.sup.2.
[0106] A fourth aspect of the invention is method of manufacturing
a layered composite comprising at least these steps:
[0107] (A) Manufacturing a mixture by at least these steps: [0108]
i) Providing a quantum material; preferably in a liquid phase;
[0109] ii) Adding a macromolecular compound comprising an anchoring
group; [0110] iii) Adding an organic additive; and [0111] iv)
optionally adding at least an organic solvent.
[0112] (B) Applying the mixture to a substrate in order to form a
layer; and
[0113] (C) Drying the layer on the substrate.
[0114] Steps i)-iv) can be carried out in individual actions or by
just combining some or all components to the mixture in one vessel
and forming the mixture by stirring the vessel's content.
[0115] A layered composite in the present context refers to an
item, which comprises at least a substrate and at least one layer.
The layered composite can have more than one layer, e.g. 2, 3, 4,
5, 6, 7, 8, 9 or 10 layers. These layers can be all positioned on
one side of the substrate. With some substrates, one or more of the
layer can be on a surface of the substrate which is averted from
the surface onto which the layer of the invention is formed.
Moreover, the layered composite can have two or more layers formed
from one or more, equal or different compositions, as mentioned
above.
[0116] Providing a substrate can be performed by any means which is
known to and considered potentially useful by a skilled person to
work the present invention. Preferred ways of providing includes
mounting on a substrate holder, placing on a rotating dish, e.g. in
a spincoater or in an inkjet printer.
[0117] A suitable substrate can be of any kind known to and
considered potentially useful by the skilled person to work the
present invention. Preferred examples of a substrate are a piece of
glass, a piece of a polymer and a layered structure.
[0118] In step (2), a macromolecular compound comprising at least
one anchoring group is added to the quantum material of step (1).
The macromolecular compound can be added as a solid, for example as
powder. It can also be dispersed or dissolved in a further liquid
phase. The liquid phase can comprise any kind of liquid phase,
optionally comprising one or more of the organic solvents, which is
known to the skilled person and considered useful to have a quantum
material and the macromolecular compound comprising at least one
anchoring group dispersed therein. Reference is made to the section
of the first aspect to the present invention regarding organic
solvents and preferred embodiments. A preferred organic phase for
this is PGMEA.
[0119] In step (3) an organic additive is added to the combined
phases of step (1) and (2). The organic additive can be added in
pure or diluted form. Preferably, the organic additive is added
pure. Reference is made to the section related to the organic
additive, as described in the first aspect to the present
invention, in particular regarding a preferred choice of organic
additive and further preferred embodiments.
[0120] In optional step (4), at least an amount of at least an
organic solvent is added. The organic solvent of this step can be
same or different to any organic solvent present in any of the
liquid phases added in any one of step (1)-(3). Reference is made
to the section of the first aspect to the present invention
regarding suited organic solvents and preferred embodiments. A
preferred organic phase for this is PGMEA.
[0121] The mixture of step (A) can be obtained by agitating the
constituents of step (1)-(3), and optionally including the
constituent of step (4). Agitation can be performed individually in
each of the aforementioned steps (1) through (3) and optionally
also in step (4). In a preferred embodiment, a liquid phase is
provided under agitation with the quantum material in step 1/, and
agitation is maintained throughout each of the further steps (2),
(3), and optionally, (4) Moreover, intervals of agitation can be
implemented between each of steps (1) through (3), and optionally
step (4). This allows the liquid phase, or a combination of the
liquid phase from step (1) with one or more further constituents to
sit and/or homogenize prior to adding another constituent.
[0122] Manufacturing of the mixture in step (A) can be operated
under inert conditions, at room temperature as well as elevated
temperature, and/or at standard pressure, elevated or reduced
pressure, all this referred to the conditions in the mixing vessel.
Preferably, step (A) is operated under inert conditions at a
temperature in the range from 0 to 100.degree. C. and ambient
pressure, which was 1 bar (101.3 kPa), based on the absolute scale
(0 kPa=absolute vacuum). Agitation can be achieved by rotating the
mixing vessel or by inserting a rotating mixer into a static mixing
vessel. A preferred mode of operation includes the use of a flask
as static mixing vessel and a stirrer.
[0123] Applying the mixture in step (B) can be performed by any
means which is known to and considered potentially useful by a
skilled person to work the present invention. Preferred ways of
applying include spin-coating and dip-coating.
[0124] After having applied the mixture to the substrate in step
(B), wherein a layer was formed, this layer is subjected to a
drying step, step (C), in order to stabilize the layer on the
substrate. For example, the drying can be a heat treatment. Any
means of heat treatment can be employed which are known to and
considered potentially useful by a skilled person to work the
present invention. Amongst them, heat treatment in a stream of hot
gas and or heating the layer in an oven are preferred. The heat
treatment may affect evaporation of solvent as well as
polymerization and/or cross-linking reactions of one or more
constituents of the composition. By such heat treatment, a stable
layer comprising the aforementioned quantum material is obtained on
the substrate.
[0125] In an embodiment of the fourth aspect of the invention, at
least one of the following features applies:
[0126] a/ The mixture obtained from step (A) is irradiated with
light prior to step (B).
[0127] b/ The layer on the substrate is irradiated with light in a
step (D) following to step (C);
[0128] wherein the light has a wavelength selected from a range of
300 to 600 nm having an intensity in the range from 0.025 to 1
W/cm.sup.2 to obtain the composition.
[0129] It was found that exposing a mixture comprising a quantum
material as described above to light could enhance the quantum
yield of the mixture compared with a mixture which is not treat
this way. The irradiation with light can be light of any
wavelength, spectrum and intensity, considered possibly suitable by
a skilled person.
[0130] In an embodiment of the invention, the wavelength of the
light is selected in the range of 350-500 nm. The intensity of
light can be same or varying with the wavelength over the
spectrum.
[0131] In another embodiment of the invention, a single wavelength
of light can be chosen. In this case more than 90% of the light
applied has a wavelength of the mentioned wavelength.+-.2 nm.
[0132] In another embodiment of the invention, the intensity of the
light is in the range from 0.05 to 0.5 W/cm.sup.2.
[0133] It was further found that the efficiency of a layer on a
substrate can be enhanced, when exposing the layer comprising a
quantum layer to irradiation, as in step b/. The layer can be a
liquid phase, for example as in step (B) of the fourth aspect of
the invention, or a solid layer of a layered composite, for example
as in the sixth aspect of the invention. Preferred embodiments are
the same as the embodiments described about step a/.
[0134] A fifth aspect of the invention is layered composite
obtainable by the method of the fourth aspect or one of its
embodiments. As already mentioned, a preferred layered composite
comprises a substrate and at least a layer wherein the at least one
layer is a polymer film.
[0135] In a preferred embodiment, the thickness of the layer is in
the range of 0.5 .mu.m to 200 .mu.m, for example from 2 to 100
.mu.m, or from 4 to 50 .mu.m. The thickness of the layer is most
preferred in the range from 4 to 50 .mu.m. The thickness of the
layer is determined in a direction perpendicular to a plane created
by the surface of the substrate which is adjacent to the layer, and
the multiple layers respectively. The thickness of the layer can be
determined by cutting a sample piece and analyzing the layers along
the cut perpendicular through the substrate using Scanning Electron
Microscopy (SEM). Two or more layers can be part of the layered
composite by further preference.
[0136] A sixth aspect of the invention is a layered composite
comprising,
[0137] .alpha.) A substrate; and
[0138] .beta.) At least a layer comprising;
[0139] a. A quantum material;
[0140] b. A macromolecular compound comprising at least one
anchoring group;
[0141] c. An organic additive.
[0142] Preferred embodiments of the components of the sixth aspect
of the invention, in particular of the substrate, the quantum
material, their coating, the macromolecular compound comprising at
least one anchoring group and the organic additive are the same as
described above, and in particular as those described with respect
to the first, the third, fourth and the fifth aspect of the
invention. The at least one layer in .beta.) is preferably obtained
from a composition according to the first aspect of the invention
or one of its embodiments, and/or by one of the methods according
to the second and fourth aspect of the invention, and the
embodiments thereto.
[0143] A seventh aspect of the invention is an optical device
comprising a layered composite as described above or as obtainable
by aforementioned processes. The Layered composite can be an
optical sheet, for example, a color filter, a color conversion
film, remote phosphor tape, or another film or filter.
[0144] The optical device comprising the layered composite can any
known to the skilled person. Examples of such optical device are a
liquid crystal display device (LCD), an organic light emitting
diode (OLED), a backlight unit for an optical display, a light
emitting diode device (LED), micro electro mechanical systems (here
in after "MEMS"), electro wetting display, an electrophoretic
display, a lighting device and a solar cell.
[0145] A eighth aspect of the invention is a use of an organic
additive for improving the emission efficiency of a quantum
material. A way to determine the emission efficiency is measuring
the quantum yield of light which travels through a layered
composite as described above.
[0146] A ninth aspect of the invention is a use of an organic
additive for dispersing a quantum material in a matrix polymer.
[0147] In a preferred embodiment of this aspect of the invention,
the matrix polymer can be selected from an acrylate, an epoxy
resin, a polyurethane and a polysiloxane, or a combination of two
or more thereof.
[0148] Test Methods
[0149] Quantum Yield
[0150] Measurements of Quantum Yield (QY), Center Wavelength (CWL,
also referred to as: peak wavelength) and Full width half max
(FWHM, also referred to as: peak band) in solutions are performed
on a Hamamatsu Quantaurus QY Absolute PL quantum yield spectrometer
C11347-11 (in the following referred to as "Hamamatsu
Quantaurus").
PREFERRED EMBODIMENTS
[0151] Embodiment 1. A composition comprising at least these
components:
[0152] i) a semiconducting light emitting nanoparticle;
[0153] ii) a macromolecular compound comprising at least an
anchoring group;
[0154] iii) an organic additive.
[0155] Embodiment 2. The composition of embodiment 1, wherein the
organic additive is defined by formula (Ia) or (Ib)
M-(X--Y).sub.2 (Ia);
X--Y (Ib),
[0156] wherein
[0157] M is a divalent metal ion,
[0158] X is a hydrocarbon chain, and
[0159] Y is a functional group.
[0160] Embodiment 3. The composition according to embodiment 2,
wherein at least one of the following applies:
[0161] a) M is selected from the group consisting of Zn.sup.2+,
Mg.sup.2+ and Cd.sup.2+;
[0162] b) Y is selected from the group consisting of carboxylate,
carbamate, xanthate, phosphonate, phosphate, thiolate;
[0163] or a combination of two or more thereof.
[0164] Embodiment 4. The composition any one of embodiments 1 to 3,
wherein the organic additive is defined by formula (II),
##STR00002##
[0165] wherein
[0166] M is selected from the group consisting of Zn.sup.2+,
Mg.sup.2+ and Cd.sup.2+;
[0167] R.sub.1 and R.sub.2 can be same or different, linear or
branched, and each R.sub.1, R.sub.2 is selected from the group
consisting of an alkyl having a chain of 1 to 16 carbons atoms or
an alkenyl group having a chain of 1 to 15 carbon atoms.
[0168] Embodiment 5. The composition of any one of the preceding
embodiments, wherein the organic additive comprises a Zinc
carboxylate.
[0169] Embodiment 6. The composition of any one of the preceding
embodiments, wherein the at least one anchoring group of the
macromolecular compound is ionic.
[0170] Embodiment 7. The composition of any one of the preceding
embodiments, wherein the at least one anchoring group of the
macromolecular compound is selected from the group consisting of
phosphine group, phosphine oxide group, phosphate group,
phosphonate group, thiol group, tertiary amine, carboxyl group,
hetero cyclic group, silane group, sulfonic acid, hydroxyl group;
or a combination of two or more thereof.
[0171] Embodiment 8. The composition of any one of the preceding
embodiments, wherein the macromolecular compound has a number
average molecular weight of at least 1,000 g/mol.
[0172] Embodiment 9. The composition of any one of the preceding
embodiments, wherein the macromolecular compound is based on a
copolymer.
[0173] Embodiment 10. The composition of embodiment 9, wherein the
copolymer is selected from the group consisting of graft copolymer,
block copolymer, alternating copolymer, random copolymer.
[0174] Embodiment 11. The composition of any one of the preceding
embodiments, wherein the macromolecular compound comprises at least
one acrylate.
[0175] Embodiment 12. The composition of any one of the preceding
embodiments, wherein the composition further comprises at least an
organic phase.
[0176] Embodiment 13. The composition of any one of the preceding
embodiments, wherein the composition further comprises a matrix
polymer.
[0177] Embodiment 14. The composition of embodiment 13, wherein the
matrix polymer is selected from an acrylate, an epoxy resin, a
polyurethane and a polysiloxane.
[0178] Embodiment 15. A method of manufacturing a composition with
improved quantum yield, comprising at least these steps:
[0179] (a) Manufacturing a mixture by at least these steps:
[0180] 1/ Providing a semiconducting light emitting
nanoparticle,
[0181] 2/ Adding a macromolecular compound comprising at least an
anchoring group;
[0182] 3/ Adding an organic additive
[0183] (b) Subjecting the mixture from step (a) to irradiation with
light of a wavelength selected from a range of 300 to 600 nm having
an intensity in the range from 0.025 to 1 W/cm.sup.2 to obtain the
composition.
[0184] Embodiment 16. A method of manufacturing a layered composite
comprising at least these steps:
[0185] (A) Manufacturing a mixture by at least these steps:
[0186] (1) Providing a semiconducting light emitting
nanoparticle;
[0187] (2) Adding a macromolecular compound comprising at least an
anchoring group;
[0188] (3) Adding an organic additive;
[0189] (B) Applying the mixture to a substrate in order to form a
layer; and
[0190] (C) Drying the layer on the substrate.
[0191] Embodiment 17. The method of embodiment 16, wherein the at
least one of the following features applies:
[0192] (a) The mixture obtained from step (A) is irradiated with
light prior to step (B);
[0193] (b) The layer on the substrate is irradiated with light in a
step (D) following to step (C);
[0194] wherein the light has a wavelength selected from a range of
300 to 600 nm having an intensity in the range from 0.025 to 1
W/cm.sup.2 to obtain the composition.
[0195] Embodiment 18. A layered composite obtainable or obtained by
the method of embodiment 16 or 17.
[0196] Embodiment 19. A layered composite comprising:
[0197] .alpha.) A substrate;
[0198] .beta.) At least a layer comprising
[0199] a. A semiconducting light emitting nanoparticle;
[0200] b. A macromolecular compound comprising at least an
anchoring group;
[0201] c. An organic additive.
[0202] Embodiment 20. An optical device comprising a layered
composite according to any one of embodiments 18 to 19.
[0203] Embodiment 21. Use of an organic additive to improve the
emission efficiency of a semiconducting light emitting
nanoparticle.
[0204] Embodiment 22. Use of light of a wavelength in the range
from 300 to 600 nm having an intensity in the range from 0.025 to 1
W/cm2 to improve the quantum yield of a composition comprising a
semiconducting light emitting nanoparticle and an organic
additive.
EXAMPLES
[0205] The following examples illustrate some aspects of the
invention. It is understood that the examples and embodiments
described herein are for illustrative purposes only and that
various modifications or changes in light thereof may be suggested
by one skilled in the art without departing from the scope of the
present invention. Accordingly, the invention is not limited by or
to the examples. Amounts mentioned in the tables below refer to
wt.-% if not indicated to the contrary.
Example 1
[0206] A solution of 0.4 ml of Propylene glycol methyl ether
acetate (PGMEA) is mixed with 0.1 ml DISPERBYK-2000 until the
solution became clear. 10 mg of pure InP(Zn)/ZnSe Quantum Dots
(Quantum Yield (QY)=20%) are added to this solution together with 3
mg of Zinc Acetate. The solution is sonicated for 10 minutes and
heated for 1 minute at 90.degree. C. After 6 hours, the obtained
solution is clear with the quantum yield of 40%. In contrast, using
the same procedure without addition of the Zinc acetate reduces the
quantum yield of the solution to 6%. The quantum yield is measured
using a Hamamatsu Quantaurus C11347 spectrometer.
TABLE-US-00001 Dispersion conditions Quantum Yield Quantum dot,
purified solution in 20% toluene Cleaned quantum dots in 6% PGMEA,
with BYK 2000 Cleaned quantum dots in 40% PGMEA, with BYK 2000 and
Zinc acetate
Example 2
[0207] A solution of 0.4 ml of Propylene glycol methyl ether
acetate (PGMEA) is mixed with 0.1 ml DISPERBYK-2000 until the
solution became clear. 80 mg of purified InP(Zn)/ZnSe Quantum dots
are added to this solution together with 10 mg of Zinc acetate. The
solution is sonicated for 10 minutes at 60.degree. C. The solution
is left for 10 hours under illumination with 450 nm LED with flux
of 300 mW/cm.sup.2. The obtained solution is clear. The quantum
yield is increased by 4% relative to the original solution of the
quantum dots in toluene. In contrast, a solution made by the same
procedure without addition of the Zinc acetate or without
illumination remains turbid showing reduced quantum yield.
TABLE-US-00002 Dispersion conditions Quantum Yield Quantum dot,
purified solution in 27% toluene 1) quantum dots in PGMEA, 2% with
BYK 2000 2) quantum dots in PGMEA, 12% with BYK 2000, illuminated
3) quantum dots in PGMEA, 8% with BYK and Zinc acetate 4) quantum
dots in PGMEA, 31% with BYK 2000 and Zinc acetate, illuminated
[0208] The Quantum yield (QY) is measured using a Hamamatsu
Quantaurus C11347 spectrometer. Quantum dots with Zinc acetate and
a treatment with light exhibit the best results.
* * * * *