Comparative DFT-based investigation of physical properties of Cs2MBiBr6 (M= Ag, Cu, and Au) Perovskites: Sustainable materials for renewable energy

• Published in: Computational Condensed Matter Vol. 38; p. e00885
• Main Authors: Ayyaz, Ahmad, Murtaza, G., Ahmed, Akhlaq, Ramay, Shahid M., Usman, Ahmad, Farid, Ghulam, Naeem, Maha
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2024
• Subjects: DFT; Elastic; Optical properties; Photovoltaic; Stability; Thermoelectric; Photovoltaic; Thermoelectric; Stability; Elastic; DFT; Optical properties
• ISSN: 2352-2143; 2352-2143
• DOI: 10.1016/j.cocom.2024.e00885

The structural, elastic, optoelectronic, optical, and thermoelectric features of Cs2MBiBr6 (M = Ag, Cu, and Au) were investigated through density functional theory (DFT) analysis. The optimization of the structure and tolerance factors ensured the stability of these cubic crystal structures. The elastic stability was validated by employing Born stability criteria based on computed elastic constants C11, C12, and C44. The formation energies ranging from −2.46 to −2.7 and negative values of Gibbs free energy confirmed the thermodynamic stability. None of these perovskites reflected perfect isotropy and Cs2AgBiBr6 only exhibited ductility. The electronic properties corresponding to their band structures, density of states, and electronic charge density were evaluated. These findings revealed the semiconducting behavior with indirect bandgaps. To evaluate the suitability for optical applications, the real and imaginary parts of dielectric functions, absorption coefficients, optical conductivities, refractive index, reflectivity, and energy loss utilizing OPTIC code in the WEIN2k interface were determined. Thermoelectric properties including the Seebeck coefficient, electrical conductivity, thermal conductivity, power factor, and figure of merit were examined by BoltzTraP code. Finally, Cs2AgBiBr6, Cs2CuBiBr6, and Cs2AuBiBr6 exhibit higher figure of merits (ZT) of 0.8, 0.79, and 0.76, respectively. Hence, these perovskites are potential candidates for future renewable energy applications.