Dynamical stability and multifunctional properties of Ni2+/Pr3+ co-doped CsPbCl3 perovskite: insights from first-principles lattice dynamics and carrier transport

Abstract

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 (ε₀ = 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.