Blue and white organic light-emitting devices using oligo(phenylenvinylene) as a blue emitter

Abstract

Highly bright and efficient blue and white organic light-emitting devices based on oligo(phenylenvinylene) derivatives, 1,4-di(4′-N,N- diphenylaminostyryl) benzene (DPA-DSB) and 2,5,2′,5′-tetrastyryl- biphenyl (TSB), are fabricated. In the blue device, using DPA-DSB doped TSB as a blue emitter, due to efficient energy transfer from TSB to DPA-DSB and depression of concentration quenching of the dopant, a maximum brightness of 17 350 cd m-2 and a maximum luminous efficiency of 12.18 cd A -1 are obtained. In the white device, DPA-DSB doped 4,4-N,N′-dicarbazole-biphenyl (CBP) acts not only as a blue emitter, but also as a blocking layer to prevent the energy transfer between the two phosphorescent layers in order to balance emissions from the three emissive layers. Combining the blue emission from it with the green and red emissions from the phosphorescent layers, white emission with a maximum brightness of 13 290 cd m-2 and a maximum luminous efficiency of 14.97 cd A -1 is obtained. The colour rendering index of the white device is 79. © 2007 IOP Publishing Ltd.