Pressure‐Induced Physical and Optoelectronic Properties of Noble Cs ₂ HfInBr ₆ for Enhanced Solar Energy Harvesting

Exploring advanced materials for energy device applications is paramount for efficient and sustainable energy solutions. Here, density functional theory (DFT)‐based simulations are carried out to systematically investigate the physical properties of a noble hafnium (Hf)–indium (In)‐based Cs 2 HfInBr 6 halide double perovskite (HDP). We demonstrate that pressure‐induced lattice confinement leads to significant changes in structural and electronic properties, resulting in transitions from semiconductor to metallic phases simultaneously direct to indirect band gap transition. Tunable electronic properties of the proposed Cs 2 HfInBr 6 perovskite portray advantageous light–matter interaction behavior, which suits this material for advanced optoelectronic devices and biomedical applications. DFT‐simulated physical behavior modeled with the finite difference time domain (FDTD) theoretical device modeling the Cs 2 HfInBr 6 solar cell demonstrates excellent power conversion efficiency of up to 27.5% with a single crystal in the planar cell under 7 GPa external pressure. This study advances energy and device engineering research by setting Cs 2 HfInBr 6 double perovskite as a promising contender for future renewable energy technology. Moreover, its unique electronic properties of multiferroic Hf─In combinations in perovskites research would pave the exciting opportunities for advancing the next generation of electronics.