SOLID-STATE LIGHT-EMITTING DEVICES BASED ON THE TRISCHELATED RUTHENIUM(II) COMPLEX - 1 - THIN-FILM BLENDS WITH POLY(ETHYLENE OXIDE)

Thin-film solid-state light-emitting devices have been fabricated by u sing blends of a trischelated complex of ruthenium(II) with 4,7-diphen yl-1,10-phenanthroline disulfonate ligands and lithium triflate comple xed poly(ethylene oxide). Charge injection occurs via an electrochemic al redox mechanism and the mechanism of light production is similar to electrogenerated chemiluminescence. Orange-red light is emitted with a turn-on voltage of 2.5-3.0 V. At 6 V, devices reach luminance levels of about 100 cd/m(2) with an external quantum efficiency of 0.02% pho tons/electron. The admired PEO acts both as a film processing aid, giv ing uniform, homogeneous, and reproducible devices, and as a polymer e lectrolyte for ruthenium complex and counterion diffusion. Devices rea ch about 50% of their maximum luminance within a few seconds, and reac h maximum luminance in about a minute. This behavior can be realized w ithout the need of elaborate charging schemes involving the use of ele vated temperatures or solvent treatments that enhance ionic conductivi ty. Devices of this type can be fabricated via conventional processing routes and conditioned to high light ouput with a few simple voltage scans.