Enhancing the efficiency of simplified red phosphorescent organic light emitting diodes by exciton harvesting

被引：58

作者：

Chang, Y-L ^{[1
]}

Wang, Z. B. ^{[1
]}

Helander, M. G. ^{[1
]}

Qiu, J. ^{[1
]}

Puzzo, D. P. ^{[1
]}

Lu, Z. H. ^{[1
]}

机构：

[1] Univ Toronto, Dept Mat Sci & Engn, Toronto, ON M5S 3E4, Canada

来源：

ORGANIC ELECTRONICS | 2012年 / 13卷 / 05期

基金：

加拿大自然科学与工程研究理事会;

关键词：

Phosphorescent organic light emitting diodes; Energy transfer; Exciton harvesting; Carrier trapping; Co-doping; HIGHLY EFFICIENT; QUANTUM EFFICIENCY; TRANSIENT ANALYSIS; IRIDIUM COMPLEXES; ELECTROPHOSPHORESCENCE; GREEN; HOST; BLUE; CARRIER; DEVICES;

D O I：

10.1016/j.orgel.2012.01.026

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

High efficiency red phosphorescent organic light emitting diode (PHOLED) employing co-doped green emitting molecule bis(2-phenylpyridine)(acetylacetonate)iridium(III) [Ir(ppy)(2)(acac)] and red emitting molecule bis(2-methyldibenzo[f,h]quinoxaline)(acetylacetonate)iridium(III) [Ir(MDQ)(2)(acac)] into 4,4'-bis(carbazol-9-yl)biphenyl (CBP) host in a simplified wide-bandgap platform is demonstrated. The green molecule is shown to function as an exciton harvester that traps carriers to form excitons that are then efficiently transferred to the Ir(MDQ)(2)(acac) by triplet-to-triplet Dexter energy transfer, thereby significantly enhancing red emission. In particular, a maximum current efficiency of 37.0 cd/A and external quantum efficiency (EQE) of 24.8% have been achieved without additional out-coupling enhancements. Moreover, a low efficiency roll-off with the EQE remaining as high as 20.8% at a high luminance of 5000 cd/m(2) is observed. (C) 2012 Elsevier B.V. All rights reserved.

引用

页码：925 / 931

页数：7

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