Triplet to singlet transition induced low efficiency roll-off in green phosphorescent organic light-emitting diodes |
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| Authors: | Zisheng Su Wenlian Li Bei Chu Shuanghong Wu |
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| Affiliation: | a Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, People's Republic of Chinab Graduate School of Chinese Academy of Sciences, Beijing 100039, People's Republic of China |
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| Abstract: | Phosphorescent organic light-emitting diodes (PHOLEDs) with an emitting layer of 4,4′-N,N′-dicarbazole-biphenyl codoped with phosphor fac-tri(phenylpyridine)iridium(III) [Ir(ppy)3] and fluorophore N,N’-dimethy-quinacridone (DMQA) are investigated. Predominant emission from DMQA due to the efficient energy transfer from Ir(ppy)3 to DMQA is observed. Such an energy transfer results in the transition of Ir(ppy)3 triplet to DMQA singlet, which reduces the Ir(ppy)3 exciton lifetime and hence suppresses the triplet-triplet annihilation and triplet-polaron annihilation of Ir(ppy)3 excitons, leading to dramatical reduction of the efficiency roll-off of the PHOLEDs. This transition of triplet to singlet strategy provides a method to improve the efficiency roll-off of the PHOLEDs. |
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| Keywords: | Phosphorescent organic light-emitting diodes Efficiency roll-off Energy transfer |
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