Luminance-enhancing polarising plate for an organic light-emitting element
There is provided a polarizer for organic light emitting diodes (OLED) having improved brightness. The polarizer, which comprises a linear polarizer and a ¼ retardation plate, comprises a reflective polarizer film disposed between the linear polarizer and the ¼ retardation plate and transmitting a polarized light horizontal to the transmission axis of the linear polarizer while reflecting a polarized light vertical to the transmission axis of the linear polarizer. The polarizer may be useful to highly improve the brightness of the OLED device when the polarizer is used in the OLED device.
1. A polarizer for organic light emitting diodes (OLED) having improved brightness, which comprises
a linear polarizer,
a ¼ retardation plate,
a reflective polarizer film disposed between the linear polarizer and the ¼ retardation plate and transmitting a horizontally polarized light to the transmission axis of the linear polarizer while reflecting a vertically polarized light vertical to the transmission axis of the linear polarizer, and
one or more adhesive layers formed on an upper surface and a lower surface of the reflective polarizer film,
wherein at least one of the one or more adhesive layers is formed of a color compensation adhesive for decreasing the reflectance of external light, and
wherein the color compensation adhesive includes an adhesive resin and a light absorbing agent, and the light absorbing agent is a mixture of dyes having an absorption wavelength of 490 to 500 nm and 580 to 590 nm.
2. The polarizer of claim 1 , wherein the light absorbing agent is present in a content of 0.01 to 1 part by weight, based on 100 parts by weight of the adhesive resin.
3. The polarizer of claim 1 , wherein the adhesive resin is selected from the group consisting of an acryl-based resin, a urethane-based resin, a polyisobutylene-based resin, a styrene-butadiene rubber (SBR)-based resin, a rubber-based resin, a polyvinylether-based resin, an epoxy-based resin, a melamine-based resin, a polyester-based resin, a phenol-based resin, a silicon-based resin, and copolymers thereof.
4. An OLED device, comprising the polarizer having improved brightness defined in claim 1 .
5. The polarizer of claim 1 , wherein the light absorbing agent is a block dye.
6. The polarizer of claim 3 , wherein the black dye has an absorption wavelength of 500 to 600 nm.