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8607085 
Journal Article 
Influence of concavo-convex interface structure on performance of phosphorescent material device 
Gao, Z; Miao, Y; Hao, Y; Wang, H; Xu, B 
2015 
Materials China 
34 
5 
342-345 
Chinese 
In this paper, a traditional phosphorescent organic light emitting device (PHOLED) with the structure of ITO/NPB(N, N0-bis(naphthalen-1-yl)-N, N0-bis(phenyl)-benzidine)/CBP(4, 4'-N, N'-two carbazole biphenyl):Ir(ppy)3 (three (2-phenyl pyridine) Iridium)/liF/Al was selected as reference, in which CBP was used as the host material, Ir(ppy) 3 served as phosphorescent dopant, NPB served as a hole transport layer. Then, the concavo-convex shape was introduced into the NPB/CBP:Ir(ppy)3 interface of reference device, to structure a series of different concavo-convex emitting layer phosphorescent devices. The electroluminescence performance of above devices was carefully investigated by using the current density-voltage-brightness and current efficiency-voltage curve, with further analysis on device interface charge trapping and injected charge dynamics. The results indicate that when the convex number is 3, the maximum current efficiency of this device is 22 cd/A, 26% higher than traditional structure device. The improvement of efficiency in concavo-convex shape emitting layer devices is attributed to the following reasons: on the one hand, concavo-convex shape emitting layer broadens the carrier recombination zone of device, further suppresses the triplet-triplet (T-T) annihilation; on the other hand, concavo-convex shape emitting layer can weaken wave guiding effects, inducing an improved light extraction efficiency. ©, 2015, Editorial Office of Materials China. All right reserved. 
Interface; Luminous efficiency; Organic light emitting devices; Phosphorescent materials