The long lifetime and diffusion lengths of carriers and the defect tolerance of lead-halide perovskites are at the heart of their high efficiency in solar cell devices. Drastic photoluminescence quantum yield enhancements upon exposure of perovskites to molecular oxygen have been reported. Despite the general consensus about a direct role of oxygen in tuning the optical properties of perovskites, the microscopic origin of this effect is still under debate. On the basis of state-of-the-art density functional theory modeling, we propose a mechanism whereby oxygen effectively inactivates deep hole traps associated with iodide interstitials by forming moderately stable oxidized products. The small energy gain associated with trap passivation is in agreement with the reversibility of the process. Vibrational analysis points at the emergence of new active modes related to oxidized defect products, spanning the 300–700 cm^–1 frequency range, which may be probed experimentally.

中文翻译：

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卤化钙钛矿中分子氧可逆陷阱钝化的机理

载体的长寿命和扩散长度以及钙钛矿型卤化铅的缺陷耐受性是它们在太阳能电池设备中高效率的核心。已经报道了钙钛矿暴露于分子氧后急剧的光致发光量子产率的提高。尽管人们普遍认为氧在调节钙钛矿的光学特性中起直接作用，但这种作用的微观起源仍在争论中。在最新的密度泛函理论模型的基础上，我们提出了一种机制，通过该机制氧可通过形成适度稳定的氧化产物来有效灭活与碘化物间隙相关的深孔陷阱。与阱钝化相关的少量能量增益与该过程的可逆性相一致。^–1频率范围，可以通过实验进行探查。