Comprehensive <scp>DFT</scp> and <scp>SCAPS</scp>‐<scp>1D</scp> Study of Structural, Electronic, Optical, Mechanical, Phonon, Thermoelectric, and Photovoltaic Properties of Lead‐Free <scp>Z<sub>3</sub>BrO</scp> (Z = K, Rb, Cs, and Fr) Anti‐Perovskites
Rifat Rafiu, Md. Sakib Hasan Saikot, Imtiaz Ahamed Apon, Imed Boukhris, Ali El‐Rayyes, Mohd Taukeer Khan, Q. Mohsen, Md. Azizur Rahman
Abstract
ABSTRACT This study presents a comprehensive first‐principles and device‐performance investigation of alkali metal‐based anti‐perovskites Z 3 BrO (Z = K, Rb, Cs, and Fr) for advanced optoelectronic and photovoltaic applications. Using density functional theory (DFT) with GGA‐PBE and mGGA‐rSCAN functionals, we analyzed the structural, electronic, optical, mechanical, phonon, population, and thermoelectric properties of these compounds. All Z 3 BrO materials exhibit direct band gaps and strong optical absorption in the visible–UV spectrum. Mechanical and phonon analyses confirm their dynamic and elastic stability, with K 3 BrO showing superior mechanical robustness and Fr 3 BrO demonstrating the highest Debye temperature. SCAPS‐1D simulations were conducted on heterostructures incorporating K 3 BrO, Rb 3 BrO, and Cs 3 BrO as absorber layers. The results revealed PCEs of 23.26% for K 3 BrO, 25.58% for Rb 3 BrO, and 26.43% for Cs 3 BrO, highlighting the tunability and performance potential of these materials. Fr 3 BrO, while excluded from device simulation due to its near‐metallic nature, exhibited promising optical and thermal features. These findings establish Z 3 BrO anti‐perovskites as promising, lead‐free absorber materials for high‐performance and sustainable solar energy technologies.