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 clarified recombination mechanism provides insight for designing perovskite nanocrystal films applied to efficient and stable light emission under high-power photoexcitation.