By using density functional theory (DFT) as implemented in WIEN2k, we examine the structural, electronic, optical, and thermoelectric properties of NaGeBr3 perovskite under hydrostatic pressures ranging from 0 to 4 GPa. The structural investigation of the cubic NaGeBr3 perovskite is determined by the Perdew Burke Ernzerhof-Generalized Gradient Approximation (PBE-GGA) functional that reveals the optimized lattice constant is 5.52 Å, which is good agreement with previous study. We calculate electronic, optical and thermoelectric properties by using the Trans Blaha-modified Becke Johnson (TB-mBJ) potential to obtain more accurate energy band gap. Band gap becomes zero from 0.81 eV to 0.00 eV with the increment of pressure from 0 GPa to 4 GPa, enhancing it’s conductivity. The optical response of NaGeBr3 are inspected by computing absorption coefficient, complex dielectric function, refractive index, reflectivity, extinction coefficient, electron energy loss, and optical conductivity. Thermoelectric properties of NaGeBr3 are investigated in terms of electrical conductivity, the Seebeck coefficient, power factor, thermal conductivity by using the BoltzTraP code. NaGeBr3 is found to be have good potential to be used in developing lead-free perovskite solar cells and other optoelectronic applications.

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