Improved white organic light-emitting devices with dual-emission-layer design

In this work, approaches to improve current efficiency of white organic light-emitting diodes (WOLEDs) with high color purity have been studied. The emission layer in devices consists of 2-(t-butyl)-9,10-bis(2´-naphthyl)anthracene (TBADN) blue host and 5,6,11,12-tetraphenylnaphthacene (rubrene) yellow dopant. The efficiency can be enhanced by using architecture of dual emission layers and hole-blocking layer. However, obvious yellow-shift emission occurs due to the small energy barrier between layers. The yellow-shift phenomenon is mitigated by modifying emission layers. The highest current efficiency of WOLED is 6.43 cd/A, which is greater by 51% than the device with single emission layer. The Commission Internationale de l¿Eclairage (CIE) coordinates of (0.33, 0.33) exhibits high color purity in WOLEDs.