Unveiling the Structural, Electronic, Optical, Mechanical, and Photovoltaic Properties of Lead-Free Inorganic New Ba3MBr3 (M = As, N, P, and Sb) Perovskites

Highly efficient, stable perovskite solar cells (PSCs) are investigated using barium (Ba)-based homologous series compound materials such as Ba3MBr3 (M = As, P, Sb, and N) as absorbers due to their exceptional light-absorbing and stability qualities. Despite achieving a power conversion efficiency (PCE) of approximately 25% with lead (Pb)-based perovskites, significant challenges persist due to their absorbing efficacy and environmental instability. Our study employs first-principles calculations (Density Functional Theory; DFT) and SCAPS-1D simulation to unveil the electronic, mechanical, optical, and solar cell characteristics of Ba3MBr3 perovskite compounds. These compounds exhibit unique geometric structures, suitable band structures, charge density distributions, and partial density of states (PDOS), with direct band-gaps ranging from 0.532 to 0.976 eV. Investigation into the photoconversion efficiency (PCE) in solar cell structures utilizing Ba3MBr3 absorbers and SnS2 electron transport layers (ETL) reveals a peak PCE of ≈29.8% in Ba3PBr3-absorber heterostructure, with VOC of 0.720 V, JSC of 49.50 mA cm–2, FF of 83.30%, and quantum efficiency (QE) ≥ 90% in the range of 300–1200 nm of AM1.5G spectra. The combined (DFT and SCAPS-1D) studies provide detailed insights into Ba-based perovskites and the necessary resources for fabricating high-efficiency, stable inorganic PSCs for advanced photovoltaic technology.