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22 August 2020 A comprehensive model of the degradation of organic light-emitting diodes
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We present a comprehensive model to analyze, quantitatively, and predict the process of degradation of OLEDs considering polaron, exciton, exciton–polaron interactions, exciton–exciton interactions and a newly proposed impurity effect. The loss of efficiency during degradation is presented as a function of quencher density. The density and generation mechanisms of quenchers are extracted using a voltage rise model. The comprehensive model is applied to stable blue phosphorescent OLEDs, and the results show that the model describes the voltage rise and external quantum efficiency loss very well, and that the quenchers in emitting layer are mainly generated by polaron-induced degradation of dopants. Quencher formation was confirmed from a mass spectrometry. The polaron density per dopant molecule is reduced by controlling the emitter doping ratio, resulting in the highest reported LT50 of 431 hours at an initial brightness of 500 cd/m2 with CIEy<0.25 and high EQE>18%.
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Jang-Joo Kim, Bomi Sim, Jongsoo Kim, Hyejin Bae, Sungho Nam, Eunsuk Kwon, Ji Whan Kim, Hwa-Young Cho, and Sunghan Kim "A comprehensive model of the degradation of organic light-emitting diodes", Proc. SPIE 11473, Organic and Hybrid Light Emitting Materials and Devices XXIV, 114730T (22 August 2020);

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