Halide substitution effects on the photovoltaic properties of Ca<sub>3</sub>PX<sub>3</sub> (X = F, Cl, Br, I) perovskites: advancing solar cell efficiency

Herein, the fundamental physical characteristics like structural, electronic, optical parameters of the Ca3PX3 (X = F, Cl, Br, I) materials have been investigated for their potential optoelectronic applications, particularly for solar cells and related devices. To the crystallographic investigations, Ca3PI3 has the most stable configuration among all investigated materials. From the band structure analyses of these materials indicate that all materials have a direct bandgap in the range of 2.0 eV to 3.788 eV, which makes them ideal for light absorption. For the photovoltaic applications, we have analysed first-principles spectroscopic screening limited maximum efficiency (SLME) which confirms that the Ca3PI3 material exhibits the highest solar cell efficiency 29.6% and Ca3PF3 and shows lower efficiency for solar cell suitability 0.6%. Thus, these results demonstrate the real potential and abilities of halide substitution to tune the materials for particular optoelectronic devices.