Mixed Halide Passivation\nof AgBiS<sub>2</sub> Quantum\nDots for High-Performance Photodetectors

AgBiS<sub>2</sub> quantum dots (QDs) have been undergoing\nrapid\ndevelopment in recent years because of their environmental friendliness,\nabundant elemental reserves, and high optical absorption coefficients.\nHowever, previously reported ligand exchange methods for AgBiS<sub>2</sub> CQDs have been ineffective in passivating surface defects,\nthereby limiting their potential for optoelectronic applications.\nIn this study, we propose a facile solution-phase ligand exchange\nmethod assisted by mixed halides for the AgBiS<sub>2</sub> CQDs. This\napproach, involving AgCl and other halides, effectively suppresses\nsurface defects and enhances the photodetector (PD) performance. The\nPD exhibits significantly improved optoelectronic characteristics,\nwith a responsivity of 0.27 A W<sup>–</sup><sup>1</sup> and\na low noise power density of 6.52 × 10<sup>–9</sup> A\nHz<sup>–0.5</sup>, achieving the highest specific detectivity\nof 2 × 10<sup>12</sup> Jones compared to previous reports of\nAgBiS<sub>2</sub> CQD PDs. This mixed halide passivation strategy\nintroduces new insights into enhancing the performance of AgBiS<sub>2</sub> CQDs in PD applications.