Suppressing Energetic Disorder in Directly Synthesized Conductive AgBiS₂ Nanocrystal Inks for High-Efficiency and Eco-Friendly Photovoltaics.

Abstract

Silver bismuth sulfide (AgBiS₂) nanocrystals (NCs) have emerged as a premier eco-friendly and lead-free alternative for next-generation photovoltaics due to their exceptional light-harvesting capabilities. However, the efficiency of AgBiS₂ solar cells is fundamentally constrained by detrimental band-tail states arising from internanocrystal heterogeneity and surface defects introduced during traditional ligand exchange. In this work, we demonstrate a strategy to flatten the energy landscape of AgBiS₂ films by achieving macroscopic uniformity and long-range ordered self-assembly. By kinetically decoupling the reaction of Ag and Bi precursors, we produce highly monodisperse, directly conductive NC inks that bypass the need for efficiency-limiting ligand exchange processes. This approach ensures exceptional compositional homogeneity and suppresses nonradiative recombination, resulting in significantly enhanced carrier transport and extended lifetimes. Consequently, our eco-friendly AgBiS₂₁ solar cells achieve a power conversion efficiency of 10.52%, representing one of the highest reported values for this class of nontoxic materials. This work provides a critical paradigm for mitigating energetic disorder in multinary semiconductors, paving the way for low-cost, high-performance, and environmentally benign thin-film photovoltaics.