Exploring the structural, optoelectronic, elastic, and thermoelectric properties of cubic ternary fluoro-perovskites sodium based NaMF3 (M = Si and Ge) compounds for heterojunction solar cells applications

Abstract In the current research, the structural, optoelectronic, elastic, and thermoelectric properties of NaMF 3 (M = Si and Ge) ternary halide perovskites compounds are computed within the DFT framework using first-principle modeling. The obtained results of phonons dispersion curves and the tolerance factor is calculated for NaSiF 3 and NaGeF 3 and is found to be 1.001 and 1.004 respectively, which reveals that these compounds are structurally and thermodynamically stable in the cubic phase. The elastic constants and other mechanical parameters demonstrate that these compounds are mechanically stable, hard to scratch, ductile, anisotropic, and possess resistance to plastic distortion. The band structure and density of states (DOS) demonstrate that NaSiF 3 and NaGeF 3 compounds are semiconductors and possess a direct band gap of 1.15 eV and 3.31 eV respectively from ‘R-R’ symmetries points. The optical properties are investigated and it is observed that the selected compounds possesses strong optical conduction and absorption coefficients and are transparent at low incident photons energy ranges. This led us to the conclusion that for high-fRequency UV devices, these compounds possess suitable applications. The thermoelectric properties indicate that both materials possess notable power factors and figures of merit (ZT), due to which their applications in solar cells can be deemed. To our knowledge, this is the first theoretical computational systematic study of structural, optoelectronic, elastic, and thermoelectric properties for NaMF 3 (M = Si and Ge), which will be experimentally validated. Our findings add comprehensive insight into predicting high-performance Heterojunction Solar Cells.