Enhancing Open-Circuit Voltage and Fill Factor in Sn-Based Perovskite Solar Cells: Challenges and Opportunities for Sustainable Photovoltaics

초록

Tin (Sn)-based halide perovskite solar cells (PSCs) offer a promising lead-free alternative with favorable bandgaps and strong absorption, yet their performance is limited by substantial open-circuit voltage (V oc) and fill factor (FF) losses. This review examines the primary origins of V loss, mainly non-radiative recombination associated with undercoordinated Sn sites, deep-level defects, and the oxidation of Sn2+, all of which elevate defect densities and accelerate recombination. FF degradation is further linked to Shockley-Read-Hall (SRH) trap-assisted recombination, reflected in increased ideality factors. The review also highlights advanced characterization approaches thermal admittance spectroscopy, drive-level capacitance profiling, and emerging machine-learning tools for probing carrier dynamics and quantifying non-radiative pathways. Although progress has been made, matching the V oc and FF of Pb-based PSCs remains challenging due to the intertwined effects of oxidation chemistry, defect physics, and interfacial energetics. Recent strategies, such as molecular coordination, surface passivation, compositional engineering, and optimized charge-transport interlayers, show promise in suppressing recombination and improving energy alignment. Continued advances in defect passivation, oxidation control, and interface engineering are expected to be key to enabling efficient and environmentally sustainable Sn-based photovoltaic technologies.

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