Band Gap Engineering in a Mixed Halide Perovskite CsPbI2Z (Z=F, Cl, Br) for Photovoltaic Applications

Authors

  • Barnabas Ngwani Kwalar
    Modibbo Adama University
  • Jamu Benson Yerima
    Modibbo Adama University
  • A. D. Ahmad
    Modibbo Adama University

Keywords:

Halide Perovskites, Bang gap, Density Functional Theory, Density of States, Quantum Espresso

Abstract

Halide perovskites are among the most promising materials for high-performance solar cells, owing to their tunable band gaps and favorable carrier transport. In this study, we apply density functional theory (DFT) with spin–orbit coupling to explore the impact of halide substitution in CsPbI2Z (Z = F, Cl, Br). Our results show that substitution systematically contracts the lattice and modifies orbital hybridization, shifting the band edges and tuning the band gap. Projected density of states analysis reveals that halide p-orbitals dominate the valence band, while Pb-p orbitals consistently govern the conduction band. Fluorine incorporation reduces the band gap from 1.45 eV to 1.40 eV, suitable for single-junction solar cells, while chlorine (1.53 eV) and bromine (1.68 eV) increase the band gap, making them attractive for tandem device configurations. All variants preserve direct band gaps at the M-point, ensuring strong light absorption. These findings establish halide substitution as a practical design pathway for optimizing CsPbI3-based perovskites toward efficient and stable photovoltaic applications

Author Biographies

Jamu Benson Yerima

Physics Department, Professor .

A. D. Ahmad

Physics Department and Associate Prof. He is my Co- Supervisor.

Dimensions

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Published

2025-12-31

How to Cite

Band Gap Engineering in a Mixed Halide Perovskite CsPbI2Z (Z=F, Cl, Br) for Photovoltaic Applications. (2025). Nigerian Journal of Theoretical and Environmental Physics, 3(4), 13-20. https://doi.org/10.62292/njtep.v3i4.2025.99

Issue

Vol. 3 No. 4 (2025): Nigerian Journal of Theoretical and Environmental Physics - Vol. 3 No. 4

Section

Articles
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How to Cite

Band Gap Engineering in a Mixed Halide Perovskite CsPbI2Z (Z=F, Cl, Br) for Photovoltaic Applications. (2025). Nigerian Journal of Theoretical and Environmental Physics, 3(4), 13-20. https://doi.org/10.62292/njtep.v3i4.2025.99