Perovskite solar cells are affordable and work well but don’t last. A new method fixes this problem without common trade-offs. What makes it different?
Perovskite solar cells can be a cheap and efficient way to produce energy, but they have a big problem—they don’t last long. Perovskite solar cells can be a cheap and efficient way to produce energy, but they have a big problem—they don’t last long. A research team from Peking University has published two papers on perovskite solar cells in Science.
Due to its photovoltaic properties, low cost, and thermal stability, formamidinium lead triiodide (FAPbI₃) is a promising absorber for high-efficiency single-junction perovskite solar cells. However, its complex crystallization kinetics and thermodynamic metastability at room temperature challenge crystallization quality and long-term stability.
Alloying strategies, such as adding methylammonium hydrochloride and Cs⁺, help control crystallization and improve photoelectric properties. However, they often leave residual additives that can lead to cation-anion separation, thermal decomposition, and unwanted chemical reactions.
These challenges make producing high-quality, non-alloyed α-FAPbI₃/perovskite films and related devices difficult. The team have introduced an iodine intercalation-declaration strategy to produce high-quality, unalloyed α-FAPbI₃ perovskite films, enhancing the efficiency and stability of perovskite solar cells.
In this approach, the strong interaction between cogenetic iodine (I₂) and I⁻ forms polyiodide ions, altering the conventional FAI + PbI₂ → FAPbI₃ reaction path to FAI₃ + PbI₂ → FAPbI₃ + I₂. This modification helps overcome barriers to α-FAPbI₃ formation.
During annealing, the volatility of I₂ ensures its complete removal from the lattice, preventing extrinsic residue and resulting in a high-quality, nonalloyed α-FAPbI₃ film. The improved crystal quality and uniformity enhance thermal stability, reducing ion migration.
Solar cells based on this nonalloyed α-FAPbI₃ film achieved a power conversion efficiency of over 24% and retained 99% of their original efficiency after more than 1,100 hours of operation at 85°C under illumination. This work highlights the team’s contributions to advancing photovoltaic technology by addressing key challenges in stability and efficiency.
References: Yu Zhang et al, Nonalloyed α-phase formamidinium lead triiodide solar cells through iodine intercalation, Science (2025). DOI: 10.1126/science.ads8968
Huachao Zai et al, Wafer-scale monolayer MoS 2 film integration for stable, efficient perovskite solar cells, Science (2025). DOI: 10.1126/science.ado2351
