Theoretical analysis of Ge-based perovskite halides for renewable energy applications

Abstract

Ab-initio characterization of NaGeX${}_3$ (X =Br, F, I) compounds has examined their structural, thermodynamical, optoelectronic, and thermoelectric characteristics. Spin polarized first principles calculations validate these compounds non-magnetic, direct band gap electronic properties. The material’s optoelectronic characteristics change when exposed to light. Controlling the material’s visible and ultraviolet optical absorption shows its disordered character. The compounds NaGeX${}_3$ (X =Br, F, I) have stable thermodynamic properties with temperature variations. As temperature increases, NaGeF${}_3$ shows significant patterns. Thermoelectric qualities include thermal and electrical conductivity, Seebeck coefficient, figure of merit ($zT$), and power factor. The study takes chemical potential $\mu$( eV) and temperature T(K) as variables. At normal ambient temperature, NaGeBr${}_3$, NaGeF${}_3$, and NaGeI${}_3$ have outstanding $zT$ values of 0.83, 0.95, and 0.82. Interestingly, the NaGeF${}_3$ compound maintains high $zT$ values from 0.95 to 0.85 across the temperature range. NaGeF${}_3$ exceeds the other two materials in renewable energy applications.