Charge localization and trapping at surfaces in lead-iodide perovskites: the role of polarons and defects,Journal of Materials Chemistry A

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Charge localization and trapping at surfaces in lead-iodide perovskites: the role of polarons and defects
Journal of Materials Chemistry A ( IF 10.7 ) Pub Date : 2020/03/18 , DOI: 10.1039/d0ta00798f
Francesco Ambrosio _{1,

2,

3,

4,

5} , Daniele Meggiolaro _{1,

2,

3,

4} , Edoardo Mosconi _{1,

2,

3,

4} , Filippo De Angelis _{1,

2,

3,

4,

6}

Affiliation

Surfaces and grain boundaries play a fundamental role in charge transport, localization and trapping in polycrystalline thin films of metal halide perovskites. Comprehension of the phenomena occurring at the surface is thus crucial to increase solar cell efficiency and, most importantly, temporal stability. We investigate charge localization and trapping at the surface of the prototypical MAPbI₃ perovskite through advanced electronic-structure calculations, considering different surface terminations. Both MAI- and PbI₂-terminated surfaces exhibit a clear spatial separation of hole and electron polarons, while a MAI-vacant surface induces charge localization at under-coordinated lead atoms. Notably, the PbI₂-terminated surface is sensitive to surface defects, which may either act as recombination centres or inhibit charge transfer at the surface, while the MAI-terminated surface is comparably more defect tolerant. We thus suggest that perovskite growth under MAI-rich conditions should be beneficial to limit surface recombination, while the synthesis of MAPbI₃ in a PbI₂-rich environment should be accompanied by surface passivation strategies to counteract the negative impact of surface defects.

中文翻译：

电荷在碘化钙钛矿中的定位和俘获：极化子和缺陷的作用

表面和晶界在金属卤化物钙钛矿的多晶薄膜中的电荷传输，局部化和俘获中起着基本作用。因此，理解在表面发生的现象对于提高太阳能电池效率以及最重要的是时间稳定性至关重要。我们通过高级电子结构计算，考虑了不同的表面终止条件，研究了原型MAPbI ₃钙钛矿表面的电荷定位和陷阱。MAI和PbI ₂终止的表面均显示出空穴和电子极化子的清晰空间分隔，而MAI空的表面在未配位的铅原子处诱导电荷定位。值得注意的是，PbI ₂端接的表面对表面缺陷敏感，表面缺陷可能充当重组中心或抑制表面上的电荷转移，而MAI端接的表面则更能容忍缺陷。因此，我们建议MAI-富条件下钙钛矿的生长应该是限制表面复合有益的，而MAPbI的合成₃在PBI薄膜₂富含环境应该通过表面钝化策略来伴随以抵消表面缺陷的负面影响。

更新日期：2020-04-08

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