Highly-efficient tandem White Organic light emitting devices

Abstract

We demonstrate efficient tandem p-i-n White Organic Light Emitting Diodes (WOLEDs) with the transparent NPB:WO3 interconnecting layer. The CIEx,y coordinate, luminance yield and E.Q.E of the tandem OLEDs (at 20 mA/cm(2)) are (0.30, 0.43), 23.9 cd/A and 8.5%, respectively. The CIEx,y coordinates of the tandem OLEDs neither change (Delta x,y < 0.02) with driving current nor with forward viewing angle (+/- 60 degree). This performance of tandem WOLEDs represents considerable improvement over what have been known in the literature.