Ink compositions, production method thereof, and method of forming quantum dot polymer composite pattern using the same
An ink composition includes a quantum dot; a carboxyl group (—COOH)-containing binder polymer; an electrical insulating polymer precursor; a radical initiator; and a liquid vehicle, wherein the liquid vehicle includes a mixture of a first organic compound including a compound represented by Chemical Formula 1, a compound represented by Chemical Formula 2, or a combination thereof, and a second organic compound including a compound represented by Chemical Formula 3, a compound represented by Chemical Formula 4, or a combination thereof:
1. An ink composition, comprising
a quantum dot;
a carboxyl group-containing binder polymer;
an electrical insulating polymer precursor;
a radical initiator; and
a liquid vehicle,
wherein the liquid vehicle comprises a mixture of a first organic compound and a second organic compound,
the first organic compound comprises a compound represented by Chemical Formula 1-1, a compound represented by Chemical Formula 2, cyclohexyl acetate, or a combination thereof:
wherein, in Chemical Formula 1-1, L is a single bond or a C1 to C3 substituted or unsubstituted alkylene group, and R is a C1 to C3 alkyl group
wherein, in Chemical Formula 2, n is 6 to 10, and each instance of R is the same or different and is independently a hydrogen or a C1 to C3 alkyl group; and
the second organic compound comprises a compound represented by Chemical Formula 3, a compound represented by Chemical Formula 4, or a combination thereof:
R 1 —COO—[C n R 2n+1 O] m —R 2 Chemical Formula 3
wherein, in Chemical Formula 3, R 1 and R 2 are the same or different and are independently a C1 to C20 alkyl group, n is an integer of 1 to 3, m is an integer of 1 to 10, and each instance of R is the same or different and is independently hydrogen or a C1 to C10 alkyl group,
wherein, in Chemical Formula 4, each instance of R is the same or different and is independently a hydrogen, a C1 to C10 alkyl group, or a C1 to C10 acyl group, and n is an integer ranging from 3 to 6,
provided that when the first organic compound is cyclohexyl acetate, then the second organic compound comprises dipropylene glycol methyl ether acetate, 2-(2-butoxyethoxy)ethyl acetate, 2-butoxyethyl acetate, 2-acetylbutyrolactone, or a combination thereof.
2. The ink composition of claim 1 , further comprising a multiple thiol compound comprising at least two thiol groups, a metal oxide particulate, or a combination thereof.
3. The ink composition of claim 1 , wherein the ink composition does not have gelation or cloudiness.
4. The ink composition of claim 1 , wherein the quantum dot comprises a Group II-VI compound, a Group III-V compound, a Group IV-VI compound, a Group IV element or compound, a Group II-III-VII compound, a Group I-II-IV-VI compound, or a combination thereof.
5. The ink composition of claim 1 , wherein
the carboxyl group-containing binder polymer comprises a copolymer of a monomer mixture comprising a first monomer comprising a carboxyl group and a carbon-carbon double bond, a second monomer comprising a carbon-carbon double bond and a hydrophobic moiety and not comprising a carboxyl group, and optionally a third monomer comprising a carbon-carbon double bond and a hydrophilic moiety and not comprising a carboxyl group, or
a multiple aromatic ring-containing polymer comprising a backbone structure comprising two aromatic rings bound to a quaternary carbon atom that is a constituent atom of another cyclic moiety in the backbone structure and comprising a carboxyl group.
6. The ink composition of claim 1 , wherein the electrical insulating polymer precursor comprises a (meth)acrylate monomer.
7. The ink composition of claim 1 , wherein the first organic compound comprises a compound represented by benzocyclohexane, benzocycloheptane, benzocyclooctane, or a combination thereof.
8. The ink composition of claim 1 , wherein the second organic compound comprises propylene glycol monomethyl ether acetate, and an amount of the propylene glycol monomethyl ether acetate is less than or equal to about 20 wt % based on a total weight of the liquid vehicle.
9. The ink composition of claim 8 , wherein the second organic compound further comprises dipropylene glycol methyl ether acetate, gamma-butyrolactone, 2-(2-butoxyethoxy)ethyl acetate, 2-butoxyethyl acetate, 2-acetylbutyrolactone, or a combination thereof.
10. The ink composition of claim 9 , wherein an amount of the propylene glycol monomethyl ether acetate is less than or equal to about 10 wt % based on a total weight of the liquid vehicle.
11. The ink composition of claim 1 , wherein, an amount of the first organic compound is greater than or equal to about 40 wt % and less than about 100 wt % based on a total weight of the liquid vehicle.
12. The ink composition of claim 1 , wherein an amount of the second organic compound is greater than 0 wt % and less than or equal to about 60 wt % based on a total weight of the liquid vehicle.
13. The ink composition of claim 1 , wherein the ink composition has a viscosity at 25° C. of greater than or equal to about 6.5 cPs and less than or equal to about 8 cPs.
14. The ink composition of claim 1 , wherein the ink composition has a surface tension at 23° C. of greater than or equal to about 27 mN/m and less than or equal to about 35 mN/m.
15. The ink composition of claim 1 , wherein the ink composition comprises a quantum dot in an amount of greater than about 40 wt % based on a total weight of the solid content.
16. The ink composition of claim 1 , wherein the ink composition comprises a quantum dot in an amount of greater than or equal to about 45 wt % based on a total weight of the solid content.
17. The ink composition of claim 1 , wherein the ink composition is configured to be sprayed through an opening having a width of less than or equal to about 40 micrometers without clogging the opening.
18. The ink composition of claim 1 , wherein the composition comprises:
about 1 wt % to about 40 wt % of the quantum dot;
about 0.5 wt % to about 35 wt % of the carboxyl group-containing binder polymer;
about 0.5 wt % to about 20 wt % of the insulating polymer precursor;
about 20 wt % to about 80 wt % of the liquid vehicle; and
about 0.01 wt % to about 10 wt % of the radical initiator.
19. A method of preparing the ink composition of claim 1 , comprising
dispersing the quantum dot in the first organic compound to prepare a quantum dot dispersion; and mixing the quantum dot dispersion with the carboxyl group-containing binder polymer, the electrical insulating polymer precursor, the radical initiator, and the second organic compound.
20. The method of claim 19 , wherein the mixing comprises dissolving the carboxyl group-containing binder polymer, and optionally, the electrical insulating polymer precursor, the radical initiator, or a combination thereof in the second organic compound to obtain a second dispersion, and mixing the second dispersion with the quantum dot dispersion.
21. A method of producing a quantum dot-polymer composite pattern comprising:
depositing the ink composition of claim 1 on a substrate by using a droplet discharging apparatus to form a patterned film; and heating the patterned film to remove the liquid vehicle and to perform polymerization of the electrical insulating polymer precursor.