Dynamical stability and multifunctional properties of Ni²⁺/Pr³⁺ co-doped CsPbCl₃ perovskite: insights from...

All-inorganic halide perovskites offer promising optoelectronic properties at low cost, but their structural softness and thermal instability limit applications. Density functional theory (DFT) using the FP-LAPW method (WIEN2k) was used to study Ni²⁺/Pr³⁺ co-doping in CsPbCl₃. Results show Ni²⁺ substitutes for Pb²⁺ at the B-site and Pr³⁺ for Cs⁺ at the A-site, keeping charge balance. Co-doping stabilizes the lattice, raises formation energies of halogen and metal vacancies, and reduces deep defect levels in the band gap. Phonon dispersion confirms that both pristine and co-doped CsPbCl₃ are dynamically stable. Ni²⁺/Pr³⁺ co-doping suppresses low-energy vibrations and causes mode splitting in the 3-5 THz range, increasing phonon scattering and lowering lattice thermal conductivity. Mechanical analysis reveals higher elastic constants and bulk modulus, while ductility remains unchanged. Electronic structure calculations reveal Ni-3d and Pr-4f states at the band edges, reducing effective carrier mass and passivating vacancy states. Optical absorption is red-shifted, and the high-frequency (ε _∞ = 2.4) and low-frequency (ε ₀ = 7.4) dielectric constants are distinct. Transport analysis finds higher carrier mobility due to lighter effective masses. Altogether, Ni²⁺/Pr³⁺ co-doping reduces defect concentrations and improves the optoelectronic properties of CsPbCl₃.