Eppur si Muove: Proton Diffusion in Halide Perovskite Single Crystals,Advanced Materials

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Eppur si Muove: Proton Diffusion in Halide Perovskite Single Crystals
Advanced Materials ( IF 27.4 ) Pub Date : 2020-10-13 , DOI: 10.1002/adma.202002467
Davide Raffaele Ceratti ₁ , Arava Zohar ₁ , Roman Kozlov _{1,

2} , Hao Dong _{1,

3} , Gennady Uraltsev ₄ , Olga Girshevitz ₅ , Iddo Pinkas ₆ , Liat Avram ₆ , Gary Hodes ₁ , David Cahen _{1,

5}

Affiliation

Ion diffusion affects the optoelectronic properties of halide‐perovskites (HaPs). Until now, the fastest diffusion has been attributed to the movement of the halides, largely neglecting the contribution of protons, on the basis of computed density estimates. Here, the process of proton diffusion inside HaPs, following deuterium–hydrogen exchange and migration in MAPbI₃, MAPbBr₃, and FAPbBr₃ single crystals, is proven through D/H NMR quantification, Raman spectroscopy, and elastic recoil detection analysis, challenging the original assumption of halide‐dominated diffusion. The results are confirmed by impedance spectroscopy, where MAPbBr₃‐ and CsPbBr₃‐based solar cells respond at very different frequencies. Water plays a key role in allowing the migration of protons as deuteration is not detected in its absence. The water contribution is modeled to explain and forecast its effect as a function of its concentration in the perovskite structure. These findings are of great importance as they evidence how unexpected, water‐dependent proton diffusion can be at the basis of the ≈7 orders of magnitude spread of diffusion (attributed to I⁻ and Br⁻) coefficient values, reported in the literature. The reported enhancement of the optoelectronic properties of HaP when exposed to small amounts of water may be related to the finding.

中文翻译：

Eppur si Muove：卤化物钙钛矿单晶中的质子扩散

离子扩散会影响卤化物钙钛矿（HaPs）的光电性能。到目前为止，在计算出的密度估计的基础上，扩散最快的归因于卤化物的运动，而在很大程度上忽略了质子的贡献。在这里，氘/氢在MAPbI ₃，MAPbBr ₃和FAPbBr ₃单晶中的氢-氢交换和迁移之后，质子在HaPs中的扩散过程通过D / H NMR定量，拉曼光谱和弹性反冲检测分析证明，这对卤化物占主导的扩散的原始假设。阻抗谱证实了结果，其中MAPbBr _3-和CsPbBr ₃基于太阳能的电池以非常不同的频率响应。水在允许质子迁移方面起着关键作用，因为在不存在氘的情况下不会检测到氘。建模水的作用是根据钙钛矿结构中的浓度来解释和预测其作用。这些结果是非常重要的，因为他们的证据意外，依赖水的质子扩散如何能在扩散蔓延级的≈7订单的基础上（归因于我^-和Br ^-）系数值，在文献报道。当暴露于少量水时，HaP的光电性能的增强报道可能与该发现有关。

更新日期：2020-11-17

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