Stability, photovoltaic, and optoelectronic properties of eco-friendly halide perovskite for solar cells applications: insights from DFT calculations

J. Islah; E. Darkaoui; A. Abbassi; S. Taj; B. Manaut; H. Ez-Zahraouy

doi:10.1140/epjb/s10051-025-00895-5

2023 Impact factor 1.6

Condensed Matter and Complex Systems

Eur. Phys. J. B (2025) 98: 51
https://doi.org/10.1140/epjb/s10051-025-00895-5

Regular Article - Computational Methods

Stability, photovoltaic, and optoelectronic properties of eco-friendly $C s G e C l_{3 - n} F_{n}$ $CsGeCl_{3-n}F_n$ halide perovskite for solar cells applications: insights from DFT calculations

J. Islah¹^a, E. Darkaoui²^b, A. Abbassi², S. Taj², B. Manaut² and H. Ez-Zahraouy¹

¹ Laboratory of Condensed Matter and Interdisciplinary Sciences “URL-CNRST”, Faculty of Sciences, University of Mohammed V, Rabat, Morocco
² Laboratory of Research in Physics and Engineering Sciences, Sultan Moulay Slimane University, Polydisciplinary Faculty, Beni Mellal, Morocco

^a islahjawad@gmail.com
^b darkaouimokhtar91@gmail.com

Received: 16 January 2025
Accepted: 2 March 2025
Published online: 28 March 2025

Abstract

This study explores the characteristics of fluorine-substituted lead-free halide perovskites $C s G e C l_{3 - n} F_{n}$ $CsGeCl_{3-n}F_n$ for clean energy applications, focusing on their structural, stability, and optoelectronic characteristics. Density functional theory (DFT) calculations, using Quantum Espresso code (QE), were performed to assess the material performance of the $C s G e C l_{3 - n} F_{n}$ $CsGeCl_{3-n}F_n$ series ( $n = 0, 1, 2, 3$ $$n=0,1,2,3$$ ). The results reveal that fluorine substitution significantly enhances both thermodynamically and mechanical stability, which are confirmed by calculated formation energy and elastic constants. The Pugh’s and Poisson ratios are estimated to confirm reduced brittleness and increased ductility in $C s G e C l_{3}$ $$CsGeCl_3$$ upon the increase of fluorine content. The electronic analysis reveals a direct semiconducting nature with a tunable band gap, increasing from 1.03 eV to 2.06 eV upon fluorine substitution. Optical analysis indicates anisotropic behavior in mixed halides perovskites, $C s G e C l_{2} F$ $$CsGeCl_2F$$ and $C s G e C l F_{2}$ $$CsGeClF_2$$ , exhibiting strong absorption coefficients on the order of $10^{5}$ $$10^5$$ cm $^{- 1}$ $^{-1}$ , low reflectivity, and weak electron–hole interactions. These findings underscore the potential of $C s G e C l_{3 - n} F_{n}$ $CsGeCl_{3-n}F_n$ perovskites for improved performance in solar cells and other optoelectronic devices. The results offer valuable insights into optimizing these materials for advanced optoelectronic applications and sustainable energy technologies.

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Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.