Enhancing Optoelectronic\nPerformance of All-Inorganic\nDouble Perovskites via Halogen Doping: Synergistic Screening Strategies\nand Multiscale Simulations

Designing all-inorganic double perovskites through element\nmixing\nis a promising strategy to enhance their optoelectronic performance\nand structural stability. The complex interplay between multilevel\nstructures and optoelectronic properties in element-mixed double perovskites\nnecessitates further in-depth theoretical exploration. In this study,\nwe employ screening strategies and multiscale simulations combining\nfirst-principles methods and device-scale continuum models to identify\ntwo novel element-mixed compounds, Rb<sub>2</sub>AgInCl<sub>3</sub>I<sub>3</sub> and Cs<sub>2</sub>AgInCl<sub>3</sub>I<sub>3</sub>,\nas promising candidates for photovoltaic applications. These compounds\nexhibit favorable structural factors and suitable direct band gaps.\nTheoretical investigations using first-principles methods with the\nHSE06 functional reveal direct band gaps of 0.98 and 1.26 eV for Rb<sub>2</sub>AgInCl<sub>3</sub>I<sub>3</sub> and Cs<sub>2</sub>AgInCl<sub>3</sub>I<sub>3</sub>, respectively, with corresponding optical absorption\ncoefficients exceeding 10<sup>5</sup> cm<sup>–1</sup> in the\nvisible light range. Cs<sub>2</sub>AgInCl<sub>3</sub>I<sub>3</sub> features high charge mobilities of approximately 20 cm<sup>2</sup>·V<sup>–1</sup>·s<sup>–1</sup> and a notable\nsingle-junction spectroscopic limited maximum efficiency (SLME) of\n25.54%. Further analysis using the device-scale continuum model simulated\nthe nonradiative recombination effects on power conversion efficiency,\nintegrating quantum-mechanically calculated optoelectronic properties.\nThese theoretical investigations, which bridge composition engineering\nwith multiscale simulations, provide valuable insights into screening\nnovel, lead-free, halogen<b>-</b>mixed double metal perovskite\noptoelectronic devices, highlighting their potential for high-performance\nsolar energy applications.