Enhanced color stability and improved performance in white organic light-emitting devices by utilizing a double-graded structure

High efficiency fluorescent white organic light-emitting device (WOLEDs) was investigated by using a double-graded (DG) structure. This strategy can greatly improve the device performances such as better color stability, higher luminance and enhanced efficiency. The optimized WOLED gives the Commission Internationale de L’Eclairage (CIE) color coordinates of (0.324, 0.341) at 20 mA/cm2, a negligible color shift of Δx, y = ±[0.000.001] from 4 to 200 mA/cm2, a maximum brightness of 39,740 cd/m2 at 17 V and a maximum luminance efficiency of 11.5 cd/A at 16 V. In addition, current-induced fluorescence quenching is mostly controlled.