TEMPO bulk passivation boosts the performance and operational stability of rapid-annealed FAPI perovskite solar cells

Perovskite solar cells could slash solar costs, yet their fragile films limit real-world use. Our study adds a trace of the benign radical TEMPO and cures the film with a 0.6 s flash-infrared pulse, giving phase-pure FAPI devices that top 20% efficiency and >90% of it being retained after 4,200 h in continuous operando conditions. The result shows that grain-boundary defects—not the perovskite lattice—drive long-term decay and that they can be tamed in a high-speed, antisolvent-free process. Because the chemistry is simple and low energy, and the curing step aligns with roll-to-roll coating, this route could cut the carbon payback of solar modules to months and enable lightweight, flexible panels for buildings and mobility. Key challenges are replacing or safely encapsulating lead, scaling the method to meter-wide uniformity, and certifying outdoor durability, but the path to commercial pilot lines is now defined with this work.