LI Shijie ^{1, 2}, GUO Zhangwang ^{1, 2}, WANG Lijing ^{1, 2}, SHI Yuxing ^{1, 2}, ZENG Tao ^{1, 2},

SHI Wei ^{1, 3}, DONG Gang ^{1, 2}, SU Xiaoli ^{1, 2}, CHEN Yunxia ^{1, 2}

(1. School of Materials and Engineering, Jingdezhen Ceramic University, Jingdezhen 333403, Jiangxi, China; 2. Jiangxi Key Laboratory of Advanced Ceramic Materials, Jingdezhen Ceramic University, Jingdezhen 333403, Jiangxi, China;

3. National Engineering Research Center for Domestic & Building Ceramics, Jingdezhen Ceramic University

Jingdezhen 333403, Jiangxi, China)

Extended abstract:[Significance] AgBiS₂ presents a promising environmentally benign photovoltaic material that addresses ecological and performance limitations of conventional solar technologies. Comprising earth-abundant, non-toxic elements (Ag, Bi, S), it circumvents the toxicity of lead-based perovskites and critical material constraints of cadmium telluride. Its superior optoelectronic properties, such as a high absorption coefficient (>10⁵ cm⁻¹) and tunable bandgap (1.1–1.7 eV), allow over 90% solar radiation capture with ~30 nm films, significantly reducing material consumption while enabling single-junction or tandem device integration. Solution-processability at low temperatures (<100 ℃) facilitates scalable manufacturing. Combined with a theoretical efficiency of ~26%, this material provides pathways to cost-effective lightweight flexible photovoltaics. Ongoing advances in interfacial engineering and defect passivation (demonstrated by 10% certified efficiency) are able to optimize carrier dynamics, positioning AgBiS₂ as a competitive alternative for next-generation solar technology that integrates environmental sustainability, high performance and industrial viability.[Progress] Recent advances in the ultrathin AgBiS₂ quantum dot solar cells (QDSCs) have been driven by synergistic progress in three domains: synthesis optimization, ligand engineering and device architecture. Initial breakthroughs began with the classical hot-injection routine. Subsequent refinements, including stoichiometric precursor control, octadecene (ODE) pre-addition for ligand stabilization, oleylamine-assisted uniform nucleation and two-step injection for large-sized quantum dots, which progressively elevated power conversion efficiency from 5.61% to 6.37%. This methodological foundation enabled novel techniques, such as room-temperature synthesis, cation exchange and eco-compatible sulfur sources. Concurrently, limitations of solid-state ligand exchange were addressed through solution-phase ligand exchange (SPLE) strategies. Molecular ink optimization, [AgI₂]⁻ complex design, AgI/AgBr dual-ligand synergistic passivation and the eco-friendly MPA-methanol system enhanced quantum dot dispersibility and interfacial passivation. These advances culminated in a record PCE of 10.8% achieved by using 3-chloro-1-propanethiol as co-ligands. Complementary innovations emerged in device architecture. Conventional ZnO/SnO₂ electron transport layers (ETLs) evolved into band-aligned TiON systems, while hole transport layers expanded beyond costly organic materials (PTB7 or PTAA) to cost-effective NiO_x-based inorganic structures with enhanced operational stability, highlighting the potential for the ultrathin photovoltaic commercialization.[Conclusions and prospects] Recent advances have propelled environmentally benign AgBiS₂ solar cells with power conversion efficiency of beyond 10%, underscoring their commercial viability. Nevertheless, research on this material remains underrepresented in photovoltaics compared to perovskite or organic counterparts, with both scientific output and device performance lagging. This review consolidates progress in AgBiS₂ quantum dot through three critical dimensions, including material synthesis, surface engineering and photovoltaic applications, while identifying unresolved challenges.(1) Synthesis Optimization: Low-temperature processing of AgBiS₂ quantum dots frequently induces cationic site disorder, leading to phase segregation and defect proliferation. Future synthesis strategies must prioritize thermodynamic control of nucleation kinetics to suppress defect-driven growth in solution-based routes.(2) Liquid-Phase Passivation Mechanisms: Although solution-phase ligand exchange (SPLE)-processed quantum dot inks enable scalable coating, inefficient passivation persists due to scarce atomic-scale ligands and undefined competitive exchange dynamics between long-/short-chain ligands. Elucidating these interfacial processes is essential for fabricating large-area, defect-minimized active layers.(3) Holistic Cost Engineering: Beyond synthesis expenses, parity attention must address device architecture costs and operational expenditures (e.g., stability limitations). Conventional structures depend on expensive hole-transport materials (e.g., PTB7) with suboptimal thermal resilience. Inverted p-i-n architectures, drawing on perovskite photovoltaics, could enhance efficiency while reducing costs, necessitating development of charge-transport layers that concurrently optimize electrical properties and broadband transparency for this configuration.

Key words: AgBiS₂ quantum dots; synthesis; ligands exchange; photoelectric conversion; performance