<title>Extraction of waveguided light by anisotropic scattering polarizer in OLED for LCD backlights</title>

Abstract

An approach to increase the coupling-out efficiency of organic light-emitting diodes (OLEDs) was studied. The approach, especially, is suitable for liquid crystal display (LCD) backlight applications. We demonstrated that the anisotropic scattering polarizer (ASP) laminated to the glass substrate surface increased the optical efficiency of OLED for LCD backlight applications. The ASP was properly prepared by drawing the liquid crystal polymer (LCP) dispersed poly(carbonate) film. The ASP could extract the emitted light trapped in substrate of OLED involved in polarization selectivity. The light extraction ability and the polarization selectivity were changed by the thickness of electron transporting layer (ETL) of OLED. The optical efficiency for 60 nm ETL thickness device through absorbing polarizer was not improved significantly by the lamination of ASP. Alternatively, the low efficiency of 120 nm ETL thickness device was effectively improved by the lamination of ASP, which was due to the extraction of waveguided light as a substantially polarized emission. Although the degree of increase for 120 nm ETL thickness device by the lamination of ASP was substantially 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.