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High‐Performance, Phosphorescent, Top‐Emitting Organic Light‐Emitting Diodes with p–i–n Homojunctions
Author(s) -
Wang Qiang,
Tao Youtian,
Qiao Xianfeng,
Chen Jiangshan,
Ma Dongge,
Yang Chuluo,
Qin Jingui
Publication year - 2011
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201002229
Subject(s) - homojunction , materials science , optoelectronics , phosphorescence , oled , ambipolar diffusion , heterojunction , diode , doping , electron , layer (electronics) , nanotechnology , optics , fluorescence , physics , quantum mechanics
High‐performance, green, orange, and red top‐emitting organic light‐emitting diodes (TOLEDs) with p–i–n homojunction are demonstrated. An excellent ambipolar host, 2,5‐bis(2‐(9H‐carbazol‐9‐yl)phenyl)‐1,3,4‐oxadiazole ( o ‐CzOXD), which has good thermal and morphological stabilities, a high triplet energy level, and equally high electron and hole mobilities, is chosen as the organic host material for the homojunction devices. By electrical doping, the carrier injection and transporting characteristics are greatly improved. The optical structure is optimized in view of light emission of different colors to enhance the color purity and improve the view characteristics. As a result, high efficiency p–i–n homojunction TOLEDs with saturated intrinsic emission of the emitting materials and angular independence of the emission are realized. The performances of these p–i–n homojunction TOLEDs are even higher than the multi‐layer heterojunction bottom‐emitting devices using the same emitting layers.