Ag-Nanoseed-MediatedDeposition Kinetics and CrystallizationBoosting toward Efficient Electrodeposited CZTSe Solar Cells on TransparentFTO Substrates

Electrodeposited Cu2ZnSn(S,Se)4 (CZTSSe) on fluorine-doped tin oxide (FTO) is promising for transparent photovoltaic devices yet constrained by inhomogeneous nucleation, inferior crystallization, and severe back-contact barriers, limiting its efficiency to ∼4.7%. Herein, a Ag nanoseed layer is developed to synergistically regulate the electrodeposition kinetics and postselenization crystallization. The Ag nanoseeds afford abundant highly active heterogeneous nucleation sites to reduce Cu2+ migration barriers and yield dense uniform metallic precursors. Upon selenization, the generated low-melting Ag–Sn–Se liquid phase accelerates grain growth and suppresses deep-level defects. Meanwhile, Ag incorporation tailors interfacial energy-level alignment and converts the unfavorable Schottky hole barrier into a hole-transport-favorable interface. Owing to these combined effects, the optimized device achieves an impressively enhanced efficiency from 3.22% to 6.30%, setting a new efficiency record for FTO-based electrodeposited CZTSe devices. This work offers a facile route toward efficient, low-cost chalcogenide photovoltaics for transparent optoelectronics.