Strain-dependent structural, electronic, mechanical, optical and thermoelectric properties of Sr₃NBr₃ perovskites for solar cell applications

Halide perovskites are a class of materials with excellent potential for solar cell applications due to their excellent optical and electronic properties. In this study, strain-dependent physical properties of Sr3NBr3 perovskites are investigated and theoretical results are reported here. The structural properties indicate that Sr3NBr3 has a cubic structure. Calculation of the formation energy confirms the thermodynamic stability of Sr3NBr3 in the pristine state and under compressive and tensile strain. Phonon dispersion curves confirm the dynamic stability of Sr3NBr3, while its mechanical stability is verified through elastic constant calculations. The material exhibits anisotropy, which diminishes under tensile strain. Additionally, the band structure and density of states are analyzed to investigate the strain-induced changes in its electronic properties. The results show that pristine and strained Sr3NBr3 systems have semiconducting nature. The Sr3NBr3 material shows excellent optical absorption in the visible range. In the energy range of 10 eV to 13 eV (ultraviolet region), an excellent reflection of up to 70% is observed for Sr3NBr3. Besides, we studied different thermoelectric features to explore the thermoelectric properties of Sr3NBr3. A high power factor of 4.46 x 1011 W m-1 K-2 s-1 is found for the hole-doped system.