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 (IIII) 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 ''-(],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.