Phosphorescent organic light-emitting devices (PHOLEDs) suffer from destructive molecular processes due to triplet-polaron and triplet-triplet annihilation. These processes are energetically driven and hence are particularly active in decreasing the lifetime of blue PHOLEDs. It has recently been shown that increasing triplet radiative rates via the Purcell effect effectively extends the device operational lifetime by reducing the triplet radiative lifetime, thus decreasing their density and the probability of triplet-annihilation reactions. We provide an analytical framework using Marcus theory to explain the observed, approximately exponential relationship between exciton energy and device lifetime. From transient drift-diffusion dynamics, we show that the Purcell effect reduces the exciton density in the steady state and increases the photoluminescent yield, thereby reducing defect generation rates and extending the device lifetime. We control the radiative rate of excitons in microcavities, thereby connecting the exciton energy and decay rates with the observed device lifetime. The device lifetime is shown to follow a power-law dependence on the Purcell factor (PFm) with m=1.5 to 2.5, dependent on the TTA-to-TPA ratio and photoluminescence quantum yield. From our analysis, a fivefold increase in PF has the potential to extend the blue PHOLED lifetime by up to 2 orders of magnitude, making the blue PHOLED lifetime comparable to that of state-of-the-art green PHOLEDs. Published by the American Physical Society 2024

中文翻译：

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了解和控制蓝色有机三重态发射器中非辐射缺陷的形成


磷光有机发光器件 （PHOLEDs） 由于三重态极化子和三重态-三重态湮灭而遭受破坏性分子过程。这些过程是由能量驱动的，因此在缩短蓝色 PHOLED 的使用寿命方面特别活跃。最近的研究表明，通过 Purcell 效应增加三重态辐射率通过缩短三重态辐射寿命来有效延长器件的使用寿命，从而降低其密度和三重态湮灭反应的可能性。我们使用 Marcus 理论提供了一个分析框架，以解释观察到的激子能量和器件寿命之间的近似指数关系。从瞬态漂移-扩散动力学中，我们表明 Purcell 效应降低了稳态下的激子密度并提高了光致发光产率，从而降低了缺陷产生率并延长了器件的使用寿命。我们控制微腔中激子的辐射率，从而将激子能量和衰减率与观察到的器件寿命联系起来。器件寿命显示遵循幂律依赖性 Purcell 因子 （PFm），m=1.5 至 2.5，具体取决于 TTA 与 TPA 的比率和光致发光量子产率。根据我们的分析，PF 增加 5 倍有可能将蓝色 PHOLED 的使用寿命延长多达 2 个数量级，使蓝色 PHOLED 的使用寿命与最先进的绿色 PHOLED 相当。 美国物理学会 2024 年出版