STUDY OF THE PHYSICAL PROPERTIES OF PEROVSKITES BASED ON CHALCOGENIDES FOR PHOTOVOLTAIC APPLICATIONS

Abstract

This thesis explores chalcogenide-based perovskites, which offer several advantages and show high potential for use in solar cells and optoelectronic technologies. Due to their exceptional band gaps and outstanding light-absorption capabilities, they are especially suitable for these applications. Using the Full-Potential Linearized Augmented Plane Wave (FP-LAPW) method within the framework of Density Functional Theory (DFT), this study aimed to evaluate the structural, elastic, electronic, optical, and thermoelectric properties of CaSiX3 systems with partial atomic substitutions (X = S, Se, or Te). The orthorhombic phase of these chalcogenides is confirmed to be both structurally and thermodynamically stable, as evidenced by optimized structural parameters and negative formation energies. Mechanical analysis shows that CaSiSe3 and CaSiTe3 are ductile, while CaSiS3 is brittle, as indicated by their Pugh and Poisson ratios. The electronic band structure calculations reveal band gaps energie of 3.02 eV for CaSiS3 and 1.71 eV for CaSiSe3, indicating that CaSiS3 is suitable for UV-light absorption and PV, while CaSiSe3 exhibits absorption in the visible red and near-infrared regions. Conversely, CaSiTe3 exhibits metallic behavior. Optical properties, such as the complex dielectric function and absorption coefficients, indicate strong ultraviolet absorption, further supporting their use in optoelectronic ultraviolet and PV applications. The AMPS-1D (Analysis of Microelectronic and Photonic Structures-One Dimensional) package was used to evaluate the solar cell efficiency, confirming their suitability for photovoltaic systems. Additionally, BoltzTrap2 was used to analyze thermoelectric properties at various temperatures, revealing figure-of-merit (ZT) values of 0.47 for CaSiS3 and 0.40 for CaSiSe3. While capable of combining solar and thermoelectric functions, these values highlight their potential for integration into renewable energy systems.