First-principles study on the stability and electric properties of Zn-doped CsPbI ₂ Br

Pb-based CsPbI 2 Br perovskite solar cells face challenges of limited optical response and Pb toxicity. This study employs first-principles calculations to explore Zn-doped CsPb 1-x Zn x I 2 Br (x=0-0.5) for structural, electronic, and mechanical properties. Results confirm the structural stability of all compositions through formation enthalpy and mechanical stability criteria. The ductility of Zn-doped perovskites suggests suitability for flexible thin-film devices. Notably, Zn doping reduces the bandgap and induces an indirect character. Nevertheless, CsPb 0.625 Zn 0.375 I 2 Br falls within the ideal range for single-junction solar cells. Density of states analysis reveals dominant Pb-6p contributions, while increasing Zn concentration enhances Zn-3d orbital involvement in the valence band, reducing Pb-6s and Pb-6p influence. The continuous band-gap tunability and the orbital redistribution upon Zn alloying provide a electronic-structure foundation for further photovoltaic exploration. These findings demonstrate Zn doping as a viable strategy to tune electronic properties and reduce Pb toxicity, providing theoretical guidance for developing eco-friendly, high-performance perovskite solar cells.