Following the remarkable success of the application of CH₃NH₃PbI₃ perovskites in photovoltaics, a great focus has been placed on their stability to improve their optoelectronic properties and seek commercial production. To gain a better understanding of their thermal stability, we investigated the chemical, morphological, and photovoltaic transformations of CH₃NH₃PbI₃ perovskites under elevated temperatures and various controlled atmospheric conditions (vacuum, 1 mbar O₂, and 1 mbar H₂O). A temperature-dependent study showed that CH₃NH₃PbI₃ decomposed to PbI₂ with the release of CH₃NH₂ and HI under low-temperature annealing (25–150 °C). Further annealing resulted in the formation of metallic lead (Pb⁰) under vacuum and Pb oxides and hydroxides under an O₂ or H₂O pressure. Moreover, the sublimation of Pb-based compounds occurred at temperatures above 150 °C, causing structural changes, which resulted in a decrease in the power conversion efficiency of the solar cell. A time-dependent study showed that, compared with vacuum conditions, the addition of O₂ or H₂O accelerated the degradation of the perovskite films.

中文翻译：

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CH ₃ NH ₃ PbI ₃钙钛矿中的热和气诱导转变及其对太阳能电池效率的影响

CH ₃ NH ₃ PbI ₃钙钛矿在光伏中的应用取得了巨大成功，继而将重点放在其稳定性上以改善其光电性能并寻求商业化生产。为了更好地了解它们的热稳定性，我们研究了CH ₃ NH ₃ PbI ₃钙钛矿在高温和各种受控大气条件（真空，1 mbar O ₂和1 mbar H ₂ O）下的化学，形态和光电转换）。温度依赖性研究表明，CH ₃ NH ₃ PbI ₃在低温退火（25–150°C）下分解为PbI ₂并释放出CH ₃ NH ₂和HI。进一步退火导致在真空下形成金属铅（Pb ⁰），并在O ₂或H ₂ O压力下形成Pb氧化物和氢氧化物。此外，基于铅的化合物的升华发生在高于150°C的温度下，引起结构变化，从而导致太阳能电池的功率转换效率降低。随时间变化的研究表明，与真空条件相比，添加O ₂或H ₂ O加速了钙钛矿薄膜的降解。