Coating compositions comprising polyorgano-silsesquioxane and a wavelength converting agent, and a wavelength converting sheet using the same
The present invention relates to a coating composition having excellent wavelength conversion efficiency and a wavelength converting thin film/sheet prepared using the same. The coating composition of the present disclosure includes 1 to 60 wt % of polyorgano-silsesquioxane, 0.0001 to 30.0 wt % of a wavelength converting agent, and a solvent, and exhibits a transmittance of 70% or more as compared to that of an aqueous solution. A wavelength converting thin film/sheet prepared by using the coating composition has not only excellent photoluminescence, thermal resistance, and light-fastness, but also moisture and oxygen permeability is low, and the visible light transmittance thereof is 70% or more as compared to that of the air, and when patterning is added, the photoluminescence intensity of sheet is at least two-fold higher than that of a non-patterned sheet. Therefore, the coating composition of the present invention may be conveniently used in the preparation of a wavelength converting thin film/sheet, and feasibly applied to the preparation of a solar cell in an efficient manner.
1. A method for preparing a wavelength converting sheet, comprising the steps of:
(a) applying the following coating composition on a substrate,
wherein the coating composition comprises 1.0 to 60 wt % of polyorgano-silsesquioxane represented by the following Formula 1, 0.0001 to 30 wt % of a wavelength converting agent, and a solvent:
wherein in the Formula 1, R 1 and R 2 are independently selected from the group consisting of a C 1 -C 10 straight chain or branched chain alkyl group, a vinyl group, a C 6 -C 10 aryl group, a C 7 -C 16 aralkyl group, a C 7 -C 16 alkaryl group, a C 3 -C 15 cycloalkyl group, a C 4 -C 20 alkylcycloalkyl group, a methacrylate group, an acrylate group and an epoxy group,
wherein the polyorgano-silsesquioxane has a number average molecular weight in a range of 10 2 to 10 6 , and
wherein the ratio of m to n is in a range of 6:4, and m and n are an integer of 1 to 10,000; and
(b) curing the applied substrate; and
(c) applying a polyorgano-silsesquioxane protective layer.
2. The method of claim 1 , wherein the substrate comprises plastic, stainless steel, aluminum, glass, quartz, a solar cell, an LED chip or a fiber.
3. The method of claim 1 , wherein the sheet has a visible light transmittance of 70% or more compared to that of the air.
4. The method of claim 1 , further comprising patterning a surface of the prepared sheet.
5. A wavelength converting sheet prepared according to the method of claim 1 .
6. The sheet of claim 5 , wherein the sheet is a patterned sheet and has at least two-fold higher photoluminescence intensity as compared to that of a non-patterned sheet.
7. A solar cell comprising the wavelength converting sheet of claim 5 .
8. A method for preparing a solar cell, comprising the steps of: (a) preparing a solar cell; and (b) applying the wavelength converting sheet of claim 5 on at least one surface of the solar cell to form a wavelength converting layer.