High-efficiency electrophosphorescent white organic light-emitting devices with a double-doped emissive layer

Efficient white emission with mixing of red emission from bis (1-(phenyl)isoquinoline) iridium (III) acetylanetonate [Ir(piq)2(acac)], green emission from fac (2-phenylpyridine) iridium [Ir(ppy)3], and blue emission from N, N'-bis-(1-naphthyl)-N, N'diphenyl-1,1'biphenyl-4, 4'diamine (NPB) is reported. Ir(piq)2(acac) and Ir(ppy)3 are codoped into a 2,2',2''-(1,3,5-phenylene) tris (1-phenyl-1H-benzimidazole) (TPBI) host. The device emission colour is controlled by varying dopant concentrations. The maximum luminance and power efficiency of the devices with the doping concentrations of 4 wt% Ir(ppy)3 and 2 wt% Ir(piq)2(acac) in TPBI are 33 000 cd m−2 and 10.7 lm W−1, respectively. The CIE coordinates of the device vary from (0.44, 0.44) at 5 V to (0.29, 0.34) at 18 V and are well within the white region.