用于太阳能电池的Rb2Pt1-xPdxBr6钙钛矿合金的理论研究：DFT与SCAPS-1D联合分析

Abstract In this work, we present a detailed theoretical investigation of the halide double perovskite alloy series Rb 2 Pt 1-x Pd x Br 6 (x = 0.0, 0.25, 0.5, 0.75, 1.0) using Density Functional Theory (DFT) and SCAPS-1D simulations to evaluate their potential as lead-free absorber materials for photovoltaic applications. Structural optimization confirms the stability of all compositions with calculated lattice parameters ranging from 11.46 Å for Rb 2 PdBr 6 to 11.63 Å for Rb 2 PtBr 6 , decreasing consistently with increasing Pd content due to the smaller ionic radius of Pd compared to Pt. The electronic structure analysis reveals a crucial transition in the nature of the band gap: the parent compound Rb 2 PtBr 6 exhibits an indirect band gap, while the alloys x = 0.25 and x = 0.75 transition to direct band gap semiconductors a beneficial feature for photovoltaic efficiency. The band gaps span a tunable range from 2.08 eV to 1.10 eV, becoming more favorable for solar absorption with increased Pd substitution. Mechanical and dynamical stability is confirmed via the elastic constants and phonon dispersion curves across the series. SCAPS-1D simulations reveal marked improvements in device performance, with power conversion efficiencies (PCEs) reaching up to 24.04 % for Rb 2 Pt 0.25 Pd 0.75 Br 6 , accompanied by a fill factor (FF) of 82.69 % and a short-circuit current density (J SC ) of 27.60 mA/cm 2 . These findings demonstrate that controlled Pd incorporation in Rb 2 PtBr 6 effectively tunes both the optoelectronic and mechanical properties, highlighting its promise as a lead-free perovskite absorber for next-generation photovoltaic devices.