Polymer-Based Blue Electrophosphorescent Light-Emitting Diodes Using a Bisorthometalated Ir (III) Complex as the Triplet Emitter

Polymer-based blue electrophosphorescent light-emitting diodes are reported by doping bisorthometalated (phosphine)cyanoiridium(III) complex Ir(ppy)2P(n-Bu) 3CN (ppy = 2-phenylpyridine, P(n-Bu)3 = tri-n-butylphosphine) in poly(vinylcarbazole) (PVK) as the source of emission. The (phosphine)cyanoiridium(III) complex shows sky blue emission with two peaks at 467 and 496 nm originating from an admixture of triplet metal-to-ligand charge-transfer and ligand-centered states. The PL and EL spectra of an Ir(ppy)2P(n-Bu)3CN-doped PVK film and device exhibited no emission from PVK, indicating that the energy transfer from PVK to Ir(ppy) 2P(n-Bu)3CN is efficient. A maximum external quantum efficiency ((eta)ex) of 1.45% and power efficiency ((eta)p) of 0.99 lm/W were achieved at 13 and 6 mA/cm^2 at a 10 wt % doping concentration, respectively.