Researchers from Nanjing University of Aeronautics and Astronautics in China and the UK's University of Cambridge have reported a scalable stabilization method using vapor-phase fluoride treatment, which achieved 18.1%-efficient perovskite solar modules (228 square centimeters) with accelerated aging–projected T80 lifetimes (time to 80% of efficiency remaining) of 43,000 ± 9000 hours under 1-sun illumination at 30°C.
The high stability results from vapor-enabled homogeneous fluorine passivation over large-area perovskite surfaces, suppressing defect formation energy and ion diffusion. The extracted degradation activation energy of 0.61 electron volts for solar modules is comparable to that of most reported stable cells, which indicates that modules are not inherently less stable than cells and closes the cell-to-module stability gap.
The scientists alleviated evaporation-driven concentration fluctuations during solution coating of stabilizing layers by exposing formamidinium lead iodide films to hydrogen fluoride vapor generated by heating ammonium fluoride in a sealed chamber. The strong lead-fluoride bonds suppressed defect formation and immobilized anions near the surface.
