Extraction of waveguided light by anisotropic scattering polarizer in OLED for LCD backlights

摘要

We demonstrated that the anisotropic scattering polarizer (ASP) laminated to glass substrate surface increased the optical efficiency of organic electroluminescent (EL) device for liquid crystal display (LCD) backlight applications. ASP was properly prepared by drawing the liquid crystal polymer (LCP) dispersed poly(carbonate) film. ASP could extract emitting light trapped in substrate of organic EL devices involved in polarization selectivity. Light extraction ability and polarization selectivity were changed by the thickness of electron transporting layer (ETL) of organic EL devices. Optical efficiency for 60 nm ETL thickness device through absorbing polarizer was not improved so much by the lamination of ASP. Whereas, low efficiency of 120 nm ETL thickness device was effectively improved by the lamination of ASP, which was due to extracting waveguided light as a substantially polarized emission. Although the degree of increase for 120 nm ETL thickness device by the lamination of ASP was very large, the final optical efficiency was less than or comparable to that for 60 nm ETL thickness device. However, in the case of 90 nm ETL thickness device, the lamination of ASP increased the optical efficiency by the factor of 1.2-1.3 against 60 nm ETL thickness device.