Ipat of A-site cation substitution on the defect chemistry and mobilities of ASnBr 3 perovskites Adair Nicolson 1 , Seán R. Kavanagh 1,2 , James R. Neilson 3 , David O. Scanlon 1 1 Department of Chemistry, University College London, UK, 2 Department of Materials, Imperial College London, UK, 3 Department of Chemistry, Colorado State University, USA Halide perovskites hae been intensely studied over the last decade due to their optoelectronic properties, with applications ranging from solar cells to LEDs. However, the majority of the best performing devices contain Pb(II), raising concerns over their toxicity. A standard solution to this problem is to perform chemical substitution, swapping Sn(II) for Pb(II) in order to retain the beneficial perovskite structure. [1] Using this technique, solar cells manufactured using CsSnBr 3 have to date achieved a record power conversion efficiency of 10.6 %. [2] To improve devices further, a detailed understanding of the factors controlling charge carrier mobility is required. The substitution of Cs with methylammonium (MA) in ASnI 3 is accompanied by a reduction in both hole and electron mobilities. [1] However, our initial experimental results indicate the reverse trend is true for ASnBr 3 . To investigate this trend, we perform hybrid DFT defect calculation, with a thorough exploration of the potential energy surface, [3] to accurately model the defect chemistry of ASnBr 3 (A = Cs, MA). These results, in combination with calculations of the charge transport properties, will provide a complete picture of the factors affecting carrier mobilities in these systems. References 1. Y.-T. Huang, S. R. Kavanagh, D. O. Scanlon, A. Walsh and R. L. Z. Hoye, Nanotechnology, 2021, 32, 132004.Almora et al., Adv. Energy Mater., 2023, 13, 2203313.Mosquera-Lois et al., JOSS, 2022, 7 (80) 4817
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