First Principle Investigation of CuCdX 3 (X = F, Cl, Br) Halide Perovskites: Structural Stability and Optoelectronic Potential for Energy Applications

First-principles density functional theory (DFT) calculations within the generalized gradient approximation were employed to investigate the structural, mechanical, electronic, and optical properties of cubic CuCdX 3 (X [Formula: see text] F, Cl, Br) perovskites. The systematic theoretical investigations of the CuCdX 3 family are provided for the first time to elucidate the structure–property relationships and halogen-dependent tunability. The CuCdX 3 (X [Formula: see text] F, Cl, Br) perovskites exhibit structural stability within the ideal perovskite range, along with ductile mechanical behavior and tunable stiffness governed by the halogen substitution. All compounds displayed indirect semiconducting band gaps with band gap values of: CuCdF[Formula: see text] eV; CuCdCl[Formula: see text] eV; and CuCdBr[Formula: see text] eV. Partial density of states analysis indicates that the valence band is mainly composed of Cu-d and halogen-p states, while Cd-d and halogen-p states dominate the conduction band. Optical studies revealed strong absorption and high dielectric response in the Visible–UV region, confirming the efficient light–matter interaction. Overall, these materials provided strong potential for flexible optoelectronic and photovoltaic applications owing to the mechanical tunability and favorable optical response.