Japanese Researchers Develop Additive to Boost Tin Perovskite Solar Cell Efficiency and Lifespan

Academic researchers from Sophia University and the National Institute for Materials Science (NIMS) in Japan have introduced a chemical additive technique that enhances both the efficiency and operational lifetime of tin-based perovskite solar cells. The development targets critical performance bottlenecks impeding the commercial rollout of non-toxic photovoltaic technologies, as first reported by TechXplore.

Perovskite photovoltaics represent a flexible, lightweight alternative to standard silicon-based solar panels. Although lead-based perovskites reach strong energy conversion metrics, the environmental toxicity of lead presents significant commercialization and regulatory hurdles. Substituting lead with tin offers a non-hazardous path forward, but tin-halide perovskite solar devices deteriorate rapidly when exposed to oxygen, creating stability and performance issues.

To address this vulnerability, the research team introduced a heteroatom compound called 2-aminobenzothiazole, or 2-ABZ, into quasi-two-dimensional Ruddlesden–Popper tin perovskites. Containing nitrogen, carbon, sulfur, and hydrogen, the molecule functions as a comprehensive stabilizer across the interior architecture of the solar device.

The study was headed by Professor Yuko Takeoka of Sophia University's Faculty of Science and Technology, alongside Dr. J. Obila—who participated while at Sophia University before joining North-West University in South Africa—and NIMS scientists Dr. Yasuhiro Shirai and Dr. Masatoshi Yanagida. Takeoka noted that the project was funded following a grant approval from the Japan Science and Technology Agency's ALCA-Next program, drawing on over 25 years of research into perovskite materials to engineer safer photovoltaic systems.

The 2-ABZ additive targets several known failure points in tin perovskites by guiding crystallization, lowering defect counts, blocking ion movement, and improving interfacial energy alignment. Takeoka stated that 2-ABZ accumulates at the interface layer to create dense nucleation centers at the base, suppressing buried defects and enabling the formation of a durable, high-quality film.

In performance testing, solar cells incorporating 2-ABZ recorded a power conversion efficiency of 9.07%, compared with 6.60% for untreated control cells. The treated solar devices also achieved improvements in open-circuit voltage, photocurrent output, and device reproducibility, alongside reduced operational hysteresis.

Surface diagnostics revealed that 2-ABZ effectively blocked the oxidation of Sn2+ into Sn4+, which serves as a main breakdown pathway for tin perovskite materials. X-ray photoelectron spectroscopy demonstrated a clear drop in oxidized iodine, while time-of-flight secondary ion mass spectrometry showed that iodide ion migration was significantly reduced.

These physical modifications yielded tangible gains during long-term operational and storage trials. Unencapsulated test units built with 2-ABZ retained 84.94% of their initial efficiency after 100 days in storage, compared to 48.95% for untreated control cells. When operated under continuous simulated sunlight, the treated cells maintained nearly 89% of initial output after 10 hours, whereas control units suffered severe performance loss during the first hour.

Because perovskite cells can be manufactured as flexible, custom-shaped surfaces rather than rigid, flat panels required by traditional silicon arrays, improving their longevity is central to expanding solar deployment. The team's research was detailed in the journal Solar RRL in a paper titled "Molecular Passivation with 2-Aminobenzothiazole Enables Efficient and Stable Ruddlesden-Popper Tin Perovskite Solar Cells."