Operando Recombination Kinetics in Perovskite Nanocrystal Films Revealed by In-Situ Time-Resolved Photoluminescence

Perovskite nanocrystals have shown great promise for optoelectronic applications. Understanding charge recombination under operational conditions, such as continuous-wave photoexcitation, is crucial for advancing device performance. Although time-resolved photoluminescence is widely used to study recombination kinetics, its reliance on ultrafast pulsed excitation fails to replicate the operational conditions. Here we develop an integrated spectroscopy platform that enables simultaneous acquisition of steady-state and time-resolved photoluminescence under continuous-wave illumination, with a wide range of photoexcitation intensity modulation. This approach resolves the long-standing mismatch between the typical time-resolved photoluminescence data and the actual continuous-wave operational behavior of perovskite nanocrystals. In contrast to the established Auger recombination model, which suggests accelerated recombination at high pump fluence, we demonstrate that the operando recombination kinetics is governed by the charge-carrier and trap-state interaction. This clarifies recombination mechanism provides insight for designing perovskite nanocrystal films applied to efficient and stable light emission under high-power photoexcitation.

钙钛矿纳米晶（Perovskite nanocrystals）在光电子学应用领域展现出巨大潜力。厘清实际工作条件（如连续波光激发（continuous-wave photoexcitation））下的电荷复合过程，对提升器件性能至关重要。尽管时间分辨光致发光（time-resolved photoluminescence）技术已被广泛用于研究复合动力学，但该技术依赖超快脉冲激发，无法复现实际工作环境中的激发条件。本研究开发了一套集成光谱平台，可在连续波照明下同时采集稳态与时间分辨光致发光信号，并支持大范围的光激发强度调制。该方法解决了长期存在的一类矛盾：传统时间分辨光致发光数据与钙钛矿纳米晶实际连续波工作行为之间的不匹配问题。与已有的俄歇复合（Auger recombination）模型（该模型提出高泵浦注量下复合过程会加速）不同，本研究证明原位（operando）复合动力学由载流子与陷阱态的相互作用主导。这一复合机制的阐明，可为设计可在高功率光激发下实现高效稳定发光的钙钛矿纳米晶薄膜提供理论指导。