Extraction of waveguided light by anisotropic scattering polarizer in organic electroluminescent devices

We demonstrated that the anisotropic scattering polarizer (ASP) laminated to a glass substrate surface increased the optical efficiency of an organic electroluminescent (EL) device for liquid crystal display (LCD) backlight applications. ASP was prepared by drawing the liquid crystal polymer (LCP) dispersed poly(carbonate) film and extracted the emitting light trapped in the substrate of an organic EL device involved in polarization selectivity. Light extraction ability and polarization selectivity were changed by thickness of the electron transporting layer (ETL) of the organic EL device. Optical efficiency of a 60 nm thick ETL device through absorbing polarizer was not much improved by the lamination of ASP, whereas low efficiency of a 120 nm thick ETL device was greatly improved by this lamination due to extraction of the waveguided light as a substantially polarized emission. Although the degree of increase for the 120 nm thick ETL device was very large, the final optical efficiency was less than or only comparable to that of the thinner device. In 90 nm thick ETL device, however, the lamination of ASP increased the optical efficiency by a factor of 1.2-1.3 against a 60nm thick ETL device. (C) 2004 The Optical Society of Japan