Stable and efficient electrophosphorescent organic light-emitting devices grown by organic vapor phase deposition

Abstract

An electrophosphorescent organic light-emitting device (PHOLED™) employing fac-tris(2-phenylpyridine)iridium [Ir(ppy)3] as the green emitting phosphor has been fabricated using a pilot-production organic vapor phase deposition (OVPD™) system. Highly controlled mass transport of the organic vapor to the substrate results in deposition rates of over 10Å∕s and spatial uniformity better than ±2% across a 150mm×150mm substrate with less than ±2% run-to-run variations. The device current–voltage, luminous efficiency, and operational lifetime performances are compared to those of a similar device grown by conventional vacuum thermal evaporation (VTE). The green OVPD-grown PHOLED exhibits a maximum external quantum efficiency of (7.0±0.1)% at a luminance of 1000cd∕m2, comparable to the VTE device performance. The operational lifetime of the OVPD-grown devices was found to be comparable to or even somewhat longer than the lifetime achieved by VTE. Furthermore, PHOLEDs with emissive layers deposited at 4.8 and 10.8Å∕s are compared, and demonstrate equivalent performance.