Highly efficient white organic electroluminescent devices based on tandem architecture

Two types of tandem organic light-emitting diodes (OLEDs) with white-light emission have been developed by using Mg:Alq3∕WO3 as the interconnecting layer. While the Commission Internationale d’Eclairage (CIE) coordinates of the tandem device with individual blue- and yellow-emitting OLEDs was sensitive to the viewing angle and the operating time, the tandem device connecting two white-emitting OLEDs was considerably less. At an optimal WO3 thickness of 5nm, the tandem two-unit device produced three higher luminance efficiency than that expected of a single-unit device. A maximum efficiency of 22cd∕A was achieved by the tandem device comprised of two white-fluorescent OLEDs, and the projected half-life under the initial luminance of 100cd∕m2 was over 80000h.