High-color-rendering pure-white phosphorescent organic light-emitting devices employing only two complementary colors

We report successful fabrication of high-color-rendering pure-white phosphorescent organic light-emitting devices (OLEDs) by employing a true-blue iridium complex Ir(dfbppy)(fbppz)2 and a wide-bandwidth yellow emitting osmium complex Os(bptz)2(dppee). The two-component phosphorescent white OLED exhibited a high color rendering index (CRI) of 81 and CIEx,y coordinates close to the ideal white emission (0.33, 0.33). By doping the yellow phosphors into the hole-transport layer and the electron-transport layer adjacent to the blue-emitting layer and thereby forming a triple-emitting-layer device structure, we obtained WOLED which exhibited rather stable colors at different biases/brightnesses. Such high-CRI pure-white two-component WOLEDs yielded EL efficiencies of up to 9.5%, 22.9 cd/A, and 20 lm/W for the forward directions.