Arber Allison Nicole, Mocanu Felix C, Islam M Saiful
Department of Materials, University of Oxford, Oxford, OX1 3PH, U.K.
Chem Mater. 2025 Jun 10;37(12):4416-4424. doi: 10.1021/acs.chemmater.5c00503. eCollection 2025 Jun 24.
Inorganic halide perovskites such as CsPbI are attracting increasing attention for solar cell and optoelectronic applications. Ion migration is known to be an important factor in perovskite behavior, but the impact of cation dopants on iodide diffusion in the room-temperature orthorhombic γ-CsPbI is not fully understood, especially at the atomic level. Here, we investigate the effect on iodide migration of incorporating different cations (including Sn, Ba, and Cu) into γ-CsPbI, focusing on maintaining an inorganic phase rather than doping with molecular organic ions. Through a combination of and machine learning (ML) techniques, our results show that the simulated structure, band gap, and ion migration energies are in good agreement with experimental data. We find that partial Pb-site substitution does not have a major suppressing effect on iodide ion transport, which is important for guiding future doping work. An ML interatomic potential model was derived for large-scale simulations (∼80 ns) of the pristine and Sn-doped materials, which reveal iodide diffusion paths along the Pb-I octahedral edges with no correlated cation motion. Structural analysis indicates an ordered cation sublattice but disorder in the anion sublattice, indicative of high iodide ion mobility similar to fast-ion conductors.
无机卤化物钙钛矿如CsPbI在太阳能电池和光电器件应用中越来越受到关注。已知离子迁移是钙钛矿性能的一个重要因素，但阳离子掺杂剂对室温正交晶系γ-CsPbI中碘化物扩散的影响尚未完全理解，尤其是在原子层面。在此，我们研究了将不同阳离子（包括Sn、Ba和Cu）掺入γ-CsPbI对碘化物迁移的影响，重点是保持无机相而非用分子有机离子进行掺杂。通过结合实验和机器学习（ML）技术，我们的结果表明，模拟的结构、带隙和离子迁移能与实验数据吻合良好。我们发现部分Pb位取代对碘离子传输没有主要的抑制作用，这对指导未来的掺杂工作很重要。针对原始材料和Sn掺杂材料的大规模模拟（约80纳秒）推导了一个ML原子间势模型，该模型揭示了碘化物沿Pb-I八面体边缘的扩散路径，且没有相关的阳离子运动。结构分析表明阳离子亚晶格有序但阴离子亚晶格无序，这表明碘离子具有与快离子导体相似的高迁移率。
