Song Zhaoning, Shrestha Niraj, Watthage Suneth C, Liyanage Geethika K, Almutawah Zahrah S, Ahangharnejhad Ramez H, Phillips Adam B, Ellingson Randy J, Heben Michael J
Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy , University of Toledo , 2801 West Bancroft Street , Toledo , Ohio 43606 United States.
J Phys Chem Lett. 2018 Nov 1;9(21):6312-6320. doi: 10.1021/acs.jpclett.8b02595. Epub 2018 Oct 22.
Organic-inorganic metal halide perovskites are notoriously unstable in humid environments. While many studies have revealed the morphology and crystal structure changes that accompany exposure to humidity, little is known about changes to the photophysics that accompany the degradation process. By combining in situ steady-state and time-resolved photoluminescence with Hall effect measurements, we examined the changes in the photoexcited carrier dynamics for methylammonium lead iodide (MAPbI) and bromide (MAPbBr) films exposed to nitrogen gas containing water vapor at 80% relative humidity. The changes in the photophysics of MAPbI interacting with water follow a four-stage process, consisting of surface passivation, free electron doping, interfacial hydration, and bulk hydration. In contrast, MAPbBr exhibits only features associated with the first two stages, which occur at a faster rate. Our results elucidate the degradation mechanisms of perovskite films in high humidity from the perspective of the photophysics, providing insights for how humidity affects the stability of the perovskite materials.
有机-无机金属卤化物钙钛矿在潮湿环境中稳定性极差。尽管许多研究揭示了暴露于湿度环境时伴随的形态和晶体结构变化，但对于降解过程中光物理性质的变化却知之甚少。通过将原位稳态和时间分辨光致发光与霍尔效应测量相结合，我们研究了在相对湿度80%的含水蒸气氮气环境中暴露的碘化甲铵铅（MAPbI）和溴化甲铵铅（MAPbBr）薄膜的光激发载流子动力学变化。MAPbI与水相互作用时的光物理变化遵循一个四阶段过程，包括表面钝化、自由电子掺杂、界面水合和体相水合。相比之下，MAPbBr仅表现出与前两个阶段相关的特征，且发生速度更快。我们的结果从光物理角度阐明了高湿度环境中钙钛矿薄膜的降解机制，为湿度如何影响钙钛矿材料的稳定性提供了见解。
