Enhancing Optoelectronic Performance of All-Inorganic Double Perovskites via Halogen Doping: Synergistic Screening Strategies and Multiscale Simulations

Designing all-inorganic double perovskites through element mixing is a promising strategy to enhance their optoelectronic performance and structural stability. The complex interplay between multilevel structures and optoelectronic properties in element-mixed double perovskites necessitates further in-depth theoretical exploration. In this study, we employ screening strategies and multiscale simulations combining first-principles methods and device-scale continuum models to identify two novel element-mixed compounds, Rb₂AgInCl₃I₃ and Cs₂AgInCl₃I₃, as promising candidates for photovoltaic applications. These compounds exhibit favorable structural factors and suitable direct band gaps. Theoretical investigations using first-principles methods with the HSE06 functional reveal direct band gaps of 0.98 and 1.26 eV for Rb₂AgInCl₃I₃ and Cs₂AgInCl₃I₃, respectively, with corresponding optical absorption coefficients exceeding 10⁵ cm^-1 in the visible light range. Cs₂AgInCl₃I₃ features high charge mobilities of approximately 20 cm²·V^-1·s^-1 and a notable single-junction spectroscopic limited maximum efficiency (SLME) of 25.54%. Further analysis using the device-scale continuum model simulated the nonradiative recombination effects on power conversion efficiency, integrating quantum-mechanically calculated optoelectronic properties. These theoretical investigations, which bridge composition engineering with multiscale simulations, provide valuable insights into screening novel, lead-free, halogen-mixed double metal perovskite optoelectronic devices, highlighting their potential for high-performance solar energy applications.