Quantifying Exciton Annihilation Effects in Thermally Activated Delayed Fluorescence Materials,Advanced Optical Materials

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Quantifying Exciton Annihilation Effects in Thermally Activated Delayed Fluorescence Materials
Advanced Optical Materials ( IF 8.0 ) Pub Date : 2021-12-06 , DOI: 10.1002/adom.202101784
Kalyani Thakur ₁ , Bas Zee ₁ , Gert‐Jan A. H. Wetzelaer ₁ , Charusheela Ramanan ₁ , Paul W. M Blom ₁

Affiliation

Important parameters for the design and performance of thermally activated delayed fluorescence (TADF) emitters are the forward and reverse intersystem crossing rates between singlet and triplet states. The magnitude of these rates is determined from the prompt and delayed transient photoluminescence decay. It is demonstrated that this photoluminescence decay strongly depends on the initial photoexcited population density due to exciton–exciton annihilation processes. By kinetic modeling of the power-dependent time-resolved photoluminescence of the TADF emitter 9,10-bis(4-(9H-carbazol-9-yl)-2,6-dimethylphenyl)-9,10-diboraanthracene (CzDBA), singlet–triplet annihilation and triplet–triplet annihilation are identified as the main loss processes with rate constants in the order of 10⁻¹⁷ m³ s⁻¹. Neglecting these quenching processes leads to erroneous estimates of the (reverse) intersystem crossing rates.

中文翻译：

量化热激活延迟荧光材料中的激子湮灭效应

热激活延迟荧光 (TADF) 发射器的设计和性能的重要参数是单重态和三重态之间的正向和反向系统间交叉率。这些速率的大小由即时和延迟的瞬态光致发光衰减确定。已经证明，由于激子-激子湮灭过程，这种光致发光衰减强烈依赖于初始光激发人口密度。通过对 TADF 发射器 9,10-bis(4-(9H-carbazol-9-yl)-2,6-dimethylphenyl)-9,10-diboraanthracene (CzDBA) 的功率依赖性时间分辨光致发光的动力学建模，单重态-三重态湮没和三重态-三重态湮没被确定为主要损失过程，速率常数约为 10 ^-17 m ³s ^-1。忽略这些淬火过程会导致对（反向）系统间交叉率的错误估计。

更新日期：2022-02-10

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