Lone-pair Bi dopants surpass Sb in orbital-defect synergistic regulation for enhanced radiative recombination in AgInS2

• • Bi doping increases the radiative recombination coefficient by one order of magnitude to 1.27×10−12 cm3/s, compared to intrinsic AgInS2 (9.63×10−13 cm3/s), directly enabling higher luminescence efficiency in light-emitting devices. • • Sb doping reduces the radiative recombination coefficient by three orders of magnitude to 1.36×10−16 cm3/s and introduces deep-level states at 1.08 eV below the conduction band minimum, exacerbating nonradiative losses and rendering Sb-doped AgInS2 unsuitable for optoelectronic applications. • • Under S-rich, In-poor, and Ag-moderate conditions, the formation energy of InAg antisite defects increases, reducing their concentration and mitigating deep-level trapping centers that limit carrier lifetimes. • • BiIn defects remain neutral across the Fermi level range, demonstrating superior defect tolerance that suppresses deep-level states, whereas SbIn defects are electrically active and detrimental to radiative recombination.