Microcavity enhancement of organic electroluminescence

Reports microcavity efficiency enhancement of organic light-emitting diodes (LEDs) based on the hole transporter bis(triphenyl)diamine (TAD) and the electron transporter and emitter tris(8-hydroxyquinoline)aluminum, Alq3. The standard, non-cavity organic LED consists of a glass substrate, an ITO electrode, 50 nm of TAD, 15 nm of Alq3 doped with the organic dye pyrromethene (PM 580) at 0.546 by weight, 35 nm of Alq3, and a highly reflecting (/spl sim/90%) low-work function electrode, such as Li:Al. The PM-580 is the emitter material in these structures. These devices typically have external quantum efficiencies /spl eta//sub ext/=1.97% 1. This corresponds to a luminous efficiency of 1.86 lm/W. The cavity organic LED has a broad bandwidth (>200 nm) TiO/sub 2/ and SiO/sub 2/ quarter-wave dielectric-stack reflector peak reflectivity (80% at 550 nm) inserted between the glass substrate and the rest of the structure.