DFT study of cubic, tetragonal and trigonal structures of KGeCl3 perovskites for photovoltaic applications
Publication Type
Journal Article
Publication Date (Issue Year)
2023
Journal Name
Computational Condensed Matter
Abstract
The study of suitable compounds for photovoltaic applications is one of the most fascinating research areas in the world. One of the less studied materials is KGeCl3 and its potential is yet to be fully determined. Investigations of the structural, electronic, optical and mechanical properties of cubic, tetragonal and trigonal structures of pure inorganic KGeCl3 perovskite have been done. All calculations have been performed using first-principle calculations based on density functional theory (DFT) in generalized gradient approximation with Perdew-BurkeErnzerhof, PBE-GGA as the exchange correlation functional, as implemented in the Quantum ESPRESSO code. Further calculations using GW approximation have been performed on electronic band structures of the three phases of KGeCl3 in order to validate the accuracy of GGA-PBE functional. The structural properties of the materials have been found to be consistent with previous observations in literature. All compounds have been found to display direct band gaps, with the top of the valence band (VB) dominated by Cl 2p orbitals and the conduction band (CB) dominated by the Ge 2p orbitals. The trigonal perovskite has been observed to have the largest band gap of 2.7 eV, with the cubic and tetragonal counterparts having 0.8 eV and 1.2 eV respectively. Calculated elastic constants, bulk and shear moduli have shown that the trigonal structure is mechanically unstable and brittle at ground state. Generally, the three phases of KGeCl3 have been observed to possess a broad absorption spectrum covering the UV–Vis region and therefore making them suitable candidates for photovoltaic applications
Keywords
DFT, Perovskites, All-inorganic, Photovoltaics, KGeCl3
Grantee Name(s)
Robinson Juma Musembi
Project Title
Research and Development of Photovoltaics based on Lead-Free Perovskite Solar Cell Technology
Type of Grant
Research Award
Thematic Area
Energy including Renewables
Funding Statement
Much appreciation to the Centre of High-Performance Computing (CHPC) in Cape Town, South Africa for providing the computational resources used in this work, through the project MATS1321. This work was carried out with the aid of a grant from UNESCO and the International Development Research Centre, Ottawa, Canada. The views expressed herein do not necessarily represent those of UNESCO, IDRC or its Board of Governors
Recommended Citation
Namisi, M. M., Musembi, R. J., Mulwa, W. M., & Aduda, B. O. (2023). DFT study of cubic, tetragonal and trigonal structures of KGeCl3 perovskites for photovoltaic applications. Computational Condensed Matter https://doi.org/10.1016/j.cocom.2022.e00772