Abstract

The need for light weight, low power multicolor displays and backlights has spurred interest in thin-film, organic electroluminescent (EL) devices. A typical organic EL device consists of an indium-tin oxide anode (ITO) layer on a glass substrate, and sequential layers of bis(triphenyl)diamine (TAD, hole transporter), tris(8-hydroxyquinoline)aluminum (A1Q, electron transporter and green light-emitter), and a low work function metal cathode (e.g., Al or Mg:Ag).¹ Device efficiency, stability, and spectral output can be tailored by incorporating intermediate layers of organic hole-blockers² or blue-emitters,³ or doping A1Q with narrow spectral linewidth organic dyes.⁴ Cavity resonance effects have been employed in lithographically patterned optical microcavities to select single⁵or multiple⁶ colors out of broad spectrum organic emitters like A1Q. Device efficiency is a critical parameter, especially for liquid crystal display backlight applications. We will describe an approach for white light EL and an approach for enhancing device efficiency.

© 1995 Optical Society of America