Breakdown of the Static Picture of Defect Energetics in Halide Perovskites: The Case of the Br Vacancy in CsPbBr 3 .

Autor:	Cohen AV; Department of Materials and Interfaces , Weizmann Institute of Science , Rehovoth 76100 , Israel., Egger DA; Institute of Theoretical Physics , University of Regensburg , 93040 Regensburg , Germany.; Department of Physics , Technical University of Munich , 85748 Garching , Germany., Rappe AM; Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States., Kronik L; Department of Materials and Interfaces , Weizmann Institute of Science , Rehovoth 76100 , Israel.
Jazyk:	angličtina
Zdroj:	The journal of physical chemistry letters [J Phys Chem Lett] 2019 Aug 15; Vol. 10 (16), pp. 4490-4498. Date of Electronic Publication: 2019 Jul 25.
DOI:	10.1021/acs.jpclett.9b01855
Abstrakt:	We consider the Br vacancy in CsPbBr 3 as a prototype for the impact of structural dynamics on defect energetics in halide perovskites (HaPs). Using first-principles molecular dynamics based on density functional theory, we find that the static picture of defect energetics breaks down; the energy level associated with a Br vacancy is found to be intrinsically dynamic, oscillating by as much as 1 eV on the picosecond time scale at room temperature. These significant energy fluctuations are correlated with the distance between the neighboring Pb atoms across the vacancy and with the electrostatic potential at these Pb atomic sites. We expect this unusually strong coupling of structural dynamics and defect energetics to bear important implications for both experimental and theoretical analyses of defect characteristics in HaPs. It may also hold significant ramifications for carrier transport and defect tolerance in this class of photovoltaic materials.
Databáze:	MEDLINE
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