The Cubic Cs2Ge2X6 (X=Cl, Br, I) double perovskite's structural, electronic, elastic, mechanical stability, phonons and optical properties are examined within the framework of Density Functional Theory (DFT). The calculated formation energy ∆HF and Goldschmidt tolerance factor (t) confirm the stability of the cubic phase in Cs2Ge2X6 (X = Cl, Br, I) compounds. Direct band gap (Eg) values for Cs2Ge2Cl6, Cs2Ge2Br6, and Cs2Ge2I6 are 1.02 eV, 0.98 eV, and 0.89 eV, correspondingly. Excellent optical absorption qualities were revealed by the computed absorption spectra of Cs2Ge2Cl6, Cs2Ge2Br6, and Cs2Ge2I6 indicating their applicability for photovoltaic applications. Based on the calculated optical spectra of the investigated compounds, the noted maximum absorption coefficients were 1.8 × 105cm-1 for Cs2Ge2Cl6, 3.3 × 105 cm-1 for Cs2Ge2Br6 and 8.8 × 104 cm-1 for Cs2Ge2I6. Among the investigated compounds, Cs2Ge2B6 exhibited the highest absorption coefficient, indicating high light harvesting capability and making it the most suitable candidate for thin film solar cells. Although Cs2Ge2Cl6 displays a slightly lower absorption coefficient, it possesses excellent optical absorption in the visible and ultraviolet regions. The high absorption coefficient demonstrate that these materials are perfect for solar cells.
| Published in | American Journal of Science, Engineering and Technology (Volume 11, Issue 4) |
| DOI | 10.11648/j.ajset.20261104.35 |
| Page(s) | 450-466 |
| Creative Commons |
This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited. |
| Copyright |
Copyright © The Author(s), 2026. Published by Science Publishing Group |
DFT, Double Perovskites, All-inorganic, Photovoltaics, Cs2Ge2X6 (X=Cl, Br, I)
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APA Style
Gabriel, M. M., Ngugi, F., Mulwa, W. M. (2026). An Ab Initio Insight into the Structural, Mechanical, Electronic and Optical Properties of Cesium Based Double Perovskites Cs2Ge2X6 (X=Cl, Br, I). American Journal of Science, Engineering and Technology, 11(4), 450-466. https://doi.org/10.11648/j.ajset.20261104.35
ACS Style
Gabriel, M. M.; Ngugi, F.; Mulwa, W. M. An Ab Initio Insight into the Structural, Mechanical, Electronic and Optical Properties of Cesium Based Double Perovskites Cs2Ge2X6 (X=Cl, Br, I). Am. J. Sci. Eng. Technol. 2026, 11(4), 450-466. doi: 10.11648/j.ajset.20261104.35
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Download@article{10.11648/j.ajset.20261104.35,
author = {Mutava Mutinda Gabriel and Fidelis Ngugi and Winfred Mueni Mulwa},
title = {An Ab Initio Insight into the Structural, Mechanical, Electronic and Optical Properties of Cesium Based Double Perovskites Cs2Ge2X6 (X=Cl, Br, I)},
journal = {American Journal of Science, Engineering and Technology},
volume = {11},
number = {4},
pages = {450-466},
doi = {10.11648/j.ajset.20261104.35},
url = {https://doi.org/10.11648/j.ajset.20261104.35},
eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ajset.20261104.35},
abstract = {The Cubic Cs2Ge2X6 (X=Cl, Br, I) double perovskite's structural, electronic, elastic, mechanical stability, phonons and optical properties are examined within the framework of Density Functional Theory (DFT). The calculated formation energy ∆HF and Goldschmidt tolerance factor (t) confirm the stability of the cubic phase in Cs2Ge2X6 (X = Cl, Br, I) compounds. Direct band gap (Eg) values for Cs2Ge2Cl6, Cs2Ge2Br6, and Cs2Ge2I6 are 1.02 eV, 0.98 eV, and 0.89 eV, correspondingly. Excellent optical absorption qualities were revealed by the computed absorption spectra of Cs2Ge2Cl6, Cs2Ge2Br6, and Cs2Ge2I6 indicating their applicability for photovoltaic applications. Based on the calculated optical spectra of the investigated compounds, the noted maximum absorption coefficients were 1.8 × 105cm-1 for Cs2Ge2Cl6, 3.3 × 105 cm-1 for Cs2Ge2Br6 and 8.8 × 104 cm-1 for Cs2Ge2I6. Among the investigated compounds, Cs2Ge2B6 exhibited the highest absorption coefficient, indicating high light harvesting capability and making it the most suitable candidate for thin film solar cells. Although Cs2Ge2Cl6 displays a slightly lower absorption coefficient, it possesses excellent optical absorption in the visible and ultraviolet regions. The high absorption coefficient demonstrate that these materials are perfect for solar cells.},
year = {2026}
}
TY - JOUR T1 - An Ab Initio Insight into the Structural, Mechanical, Electronic and Optical Properties of Cesium Based Double Perovskites Cs2Ge2X6 (X=Cl, Br, I) AU - Mutava Mutinda Gabriel AU - Fidelis Ngugi AU - Winfred Mueni Mulwa Y1 - 2026/10/28 PY - 2026 N1 - https://doi.org/10.11648/j.ajset.20261104.35 DO - 10.11648/j.ajset.20261104.35 T2 - American Journal of Science, Engineering and Technology JF - American Journal of Science, Engineering and Technology JO - American Journal of Science, Engineering and Technology SP - 450 EP - 466 PB - Science Publishing Group SN - 2578-8353 UR - https://doi.org/10.11648/j.ajset.20261104.35 AB - The Cubic Cs2Ge2X6 (X=Cl, Br, I) double perovskite's structural, electronic, elastic, mechanical stability, phonons and optical properties are examined within the framework of Density Functional Theory (DFT). The calculated formation energy ∆HF and Goldschmidt tolerance factor (t) confirm the stability of the cubic phase in Cs2Ge2X6 (X = Cl, Br, I) compounds. Direct band gap (Eg) values for Cs2Ge2Cl6, Cs2Ge2Br6, and Cs2Ge2I6 are 1.02 eV, 0.98 eV, and 0.89 eV, correspondingly. Excellent optical absorption qualities were revealed by the computed absorption spectra of Cs2Ge2Cl6, Cs2Ge2Br6, and Cs2Ge2I6 indicating their applicability for photovoltaic applications. Based on the calculated optical spectra of the investigated compounds, the noted maximum absorption coefficients were 1.8 × 105cm-1 for Cs2Ge2Cl6, 3.3 × 105 cm-1 for Cs2Ge2Br6 and 8.8 × 104 cm-1 for Cs2Ge2I6. Among the investigated compounds, Cs2Ge2B6 exhibited the highest absorption coefficient, indicating high light harvesting capability and making it the most suitable candidate for thin film solar cells. Although Cs2Ge2Cl6 displays a slightly lower absorption coefficient, it possesses excellent optical absorption in the visible and ultraviolet regions. The high absorption coefficient demonstrate that these materials are perfect for solar cells. VL - 11 IS - 4 ER -
Department of Basic Sciences, Tharaka University, Marimanti, Kenya
Department of Physics, Egerton University, Egerton, Kenya
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