Photoinduced Surface Reconstruction Strategy for Enhancing AgBiS2 Quantum Dot Solar Cells

Silver bismuth sulfide (AgBiS2) quantum dots (QDs) are promising candidates for eco-friendly solution-based solar cells. However, structural defects in QDs hinder high efficiency. Controllable synthesis of AgBiS2 QDs remains challenging, often yielding crystals with surface and lattice defects that promote nonradiative recombination. Improving AgBiS2 QD quality before film formation is crucial, as synthesis-related imperfections often persist in devices and inherently limit effective passivation later on. This study presents a photoinduced surface reconstruction method for AgBiS2 QDs that achieves nearly perfect ionic ordering with lower lattice strain, leading to denser films and better band alignment with charge layers than the initial AgBiS2 QDs. Corresponding solar cells achieve a power conversion efficiency of 9.71%, exceeding 8.16% for untreated solar cells. By enhancing AgBiS2 QD quality at the source rather than relying solely on downstream passivation, this approach offers a complementary pathway to high-performance QD solar cells.