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

An electrophosphorescent organic light-emitting device (PHOLED(TM)) 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(TM)) system. Highly controlled mass transport of the organic vapor to the substrate results in deposition rates of over 10 Angstrom/s and spatial uniformity better than +/-2% across a 150 mmx150 mm 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 1000 cd/m(2), 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 10.8 Angstrom/s are compared, and demonstrate equivalent performance. (C) 2005 American Institute of Physics.