Exploring Thermoelectric and Optoelectronic Aspects of Halide Perovskites Ca3${\rm Ca}_3$AX3${\rm AX}_3$ (A= P, As, Sb and X= Cl, Br): A DFT Study

ABSTRACT Recently, there has been growing interest in inorganic halide perovskites as a reliable and clean alternative to lead‐based hybrid perovskites. However, the fact that there is still a limited comprehensive first‐principles study about (A = P, As, Sb; X = Cl, Br) compounds hinders their exploring them for photovoltaic and thermoelectric applications. To address this gap, the present work aims to systematically study the structural, electronic, optical, and thermoelectric properties of perovskites to identify possible sustainable energy solutions by replacing lead with other elements. Density functional theory (DFT) within the full‐potential linearized augmented plane wave plus local orbitals (FP‐LAPW+lo) method was implemented in the WIEN2k code. The Perdew–Burke–Ernzerhof generalized gradient approximation (PBE‐GGA) and the modified Becke–Johnson (mBJ) potential were used to produce accurate electronic and optical results, respectively, while thermoelectric properties were studied using Boltzmann transport theory via the BoltzTraP code. All compounds crystallize in a cubic Pm‐3m structure and have direct bandgaps at the point, making them suitable for UV–visible light absorption. Optical investigation showed large absorption peaks for , while thermoelectric calculations showed with the highest power factor in both p‐type and n‐type regions. These results revealed a correlated optoelectronic behavior and thermoelectric response throughout this series. In summary, perovskites exhibit complementary optical and thermoelectric properties, making them potential candidates for future optoelectronic and sustainable energy alternatives.