Regensburg 2025 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 1: Perovskite and Photovoltaics I (joint session HL/KFM)
HL 1.9: Vortrag
Montag, 17. März 2025, 11:45–12:00, H13
Benchmarking approximations for the theoretical prediction of positron lifetimes in halide perovskites — Kajal Madaan1, •Guido Roma1, Jasurbek Gulomov1, Pascal Pochet2, Catherine Corbel3, and Ilja Makkonen4 — 1Université Paris-Saclay, CEA, Service de recherches en Corrosion et Comportement des Matériaux, SRMP, 91191 Gif sur Yvette, France — 2Department of Physics, IriG, Univ. Grenoble-Alpes and CEA, Grenoble, France — 3LSI, CEA/DRF/IRAMIS, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, Palaiseau, 91120, France — 4Department of Physics, University of Helsinki, P.O. Box 43, FI-00014 Helsinki, Finland
Positron annihilation spectroscopy is a well recognized tool for probing vacancies in materials. Recent applications of this technique to APbX3 halide perovskites are sparse, and the rare theoretical predictions of positron lifetimes in these materials, published in association with experiments, do not fully agree with each other. These works suggest that vacancies on the A site are not detected. In our theoretical study we thoroughly revisit and compare several approximations for the electron-positron correlation functional, applied to methylammonium lead iodide (MAPbI3) and CsPbI3 and their vacancies. The discrepancies between the approaches make it difficult to unequivocally exclude the presence of methylammonium vacancies in MAPbI3. Moreover, when using a truly nonlocal electron-positron correlation functional, the predicted positron density in a vacancy presents peculiar features and a much lower binding energy to the vacancy with respect to semilocal approximations.
Keywords: Halide perovskites; positron; vacancies; methylammonium; density functional theory