探究基于热激活延迟荧光的有机发光二极管中极化子诱导的激子猝灭
Probing polaron-induced exciton quenching in TADF based organic light-emitting diodes.
作者信息
Hasan Monirul, Saggar Siddhartha, Shukla Atul, Bencheikh Fatima, Sobus Jan, McGregor Sarah K M, Adachi Chihaya, Lo Shih-Chun, Namdas Ebinazar B
机构信息
School of Mathematics and Physics, The University of Queensland, Brisbane, QLD, 4072, Australia.
Centre for Organic Photonics & Electronics, The University of Queensland, Brisbane, QLD, 4072, Australia.
出版信息
Nat Commun. 2022 Jan 11;13(1):254. doi: 10.1038/s41467-021-27739-x.
Polaron-induced exciton quenching in thermally activated delayed fluorescence (TADF)-based organic light-emitting diodes (OLEDs) can lead to external quantum efficiency (EQE) roll-off and device degradation. In this study, singlet-polaron annihilation (SPA) and triplet-polaron annihilation (TPA) were investigated under steady-state conditions and their relative contributions to EQE roll-off were quantified, using experimentally obtained parameters. It is observed that both TPA and SPA can lead to efficiency roll-off in 2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN) doped OLEDs. Charge imbalance and singlet-triplet annihilation (STA) were found to be the main contributing factors, whereas the device degradation process is mainly dominated by TPA. It is also shown that the impact of electric field-induced exciton dissociation is negligible under the DC operation regime (electric field < 0.5 MV cm). Through theoretical simulation, it is demonstrated that improvement to the charge recombination rate may reduce the effect of polaron-induced quenching, and thus significantly decrease the EQE roll-off.
在基于热激活延迟荧光（TADF）的有机发光二极管（OLED）中，极化子诱导的激子猝灭会导致外量子效率（EQE）下降和器件退化。在本研究中，在稳态条件下研究了单重态极化子湮灭（SPA）和三重态极化子湮灭（TPA），并使用实验获得的参数对它们对EQE下降的相对贡献进行了量化。观察到TPA和SPA都会导致掺杂2,4,5,6-四（9H-咔唑-9-基）间苯二甲腈（4CzIPN）的OLED的效率下降。发现电荷不平衡和单重态-三重态湮灭（STA）是主要影响因素，而器件退化过程主要由TPA主导。研究还表明，在直流工作状态下（电场<0.5 MV/cm），电场诱导的激子解离的影响可以忽略不计。通过理论模拟表明，提高电荷复合率可能会降低极化子诱导猝灭的影响，从而显著降低EQE下降。
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