Solar cells based on hybrid perovskites have demonstrated very high solar energy conversion efficiency, reaching and exceeding those of silicon panels, and are, today, of global interest for next-generation photovoltaics. But perovskites have stability issues, hampering commercialization. Collaborative research on the methodology for manufacturing perovskite layers to improve their stability, and understanding the structural chemistry of these perovskites by NMR spectroscopy, involving researchers from UCCS (Lille) and Univ Rennes (FR) , Northwestern University and Rice University (USA) is published in the journal Science, 384, 6701, and featured on the cover of Science magazine.

The study presents a design strategy for the fabrication of ultrastable pure phase films of formamidinium lead iodide (FAPbI3) by network modeling using specific two-dimensional (2D) perovskites with FA as cage cation. When a pure solution of FAPbI3 precursor is contacted with the 2D perovskite, the black phase preferentially forms at 100°C, which is much lower than the standard annealing temperature of FAPbI3, which is 150°C. X-ray diffraction and optical spectroscopy suggest that the resulting FAPbI3 film compresses slightly to acquire the (011) interplanar distances of the 2D perovskite seed. Solar cells had a power conversion efficiency of 3% for a 2-square-centimeter active area and maintained 24,1% of their efficiency for 0,5 hours at 97°C under maximum power point tracking.

Link to publication: doi/10.1126/science.abq6993