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Mixed-anion mixed-cation perovskite (FAPbI3)0.875(MAPbBr3)0.125: an ab initio molecular dynamics study

Menendez-Proupin, E., Grover, S., Montero-Alejo, A. L., Midgley, S. D., Butler, K. T. and Grau-Crespo, R. ORCID: https://orcid.org/0000-0001-8845-1719 (2022) Mixed-anion mixed-cation perovskite (FAPbI3)0.875(MAPbBr3)0.125: an ab initio molecular dynamics study. Journal of Materials Chemistry A, 10 (17). pp. 9592-9603. ISSN 0959-9428

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To link to this item DOI: 10.1039/D1TA10860C

Abstract/Summary

Mixed-anion mixed-cation perovskites with (FAPbI3)1-x(MAPbBr3)x composition have allowed record efficiencies in photovoltaic solar cells, but their atomic-scale behaviour is not well understood yet, in part because their theoretical modelling requires consideration of complex and interrelated dynamic and disordering effects. We present here an ab initio molecular dynamics investigation of the structural, thermodynamic, and electronic properties of the (FAPbI3)0.875(MAPbBr3)0.125 perovskite. A special quasi-random structure is proposed to mimic the disorder of both the molecular cations and the halide anions, in a stoichiometry that is close to that of one of today´s most efficient perovskite solar cells. We show that the rotation of the organic cations is more strongly hindered in the mixed structure in comparison with the pure compounds. Our analysis suggests that this mixed perovskite is thermodynamically stable against phase separation despite the endothermic mixing enthalpy, due to the large configurational entropy. The electronic properties are investigated by hybrid density functional calculations including spin-orbit coupling in carefully selected representative configurations extracted from the molecular dynamics. Our model, that is validated here against experimental information, provides a more sophisticated understanding of the interplay between dynamic and disordering effects in this important family of photovoltaic materials.

Item Type:Article
Refereed:Yes
Divisions:Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
ID Code:104926
Uncontrolled Keywords:perovksite, solar cells, ab initio molecular dynamics, site-occupancy disorder
Publisher:Royal Society of Chemistry

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