[OPTICAL REVIEW Vol. 11, No. 6 (2004) 370-377]
© 2004 The Optical Society of Japan

Extraction of Waveguided Llight by Anisotropic Scattering Polarizer in Organic Electroluminescent Devices

Toshitaka NAKAMURA1,2,*, Hironaka FUJII2, Noriyuki JUNI2, Sadahiro NAKANISHI2, Minoru MIYATAKE2 and Naoto TSUTSUMI1*

1Department of Polymer Science and Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo, Kyoto 606-8585, Japan
2Core Technology Center, Nitto Denko Corporation, 1-1-2, Shimohozumi, Ibaraki, Osaka 567-8680, Japan

(Received April 19, 2004; Accepted September 30, 2004)

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 60 nm thick ETL device.

Key words: organic electroluminescent device, anisotropic scattering polarizer, extraction of waveguided light

*To whom all correspondence should be addressed.