Polyfluorinated Organic Diammonium Induced Lead Iodide Arrangement for Efficient Two‐Step‐Processed Perovskite Solar Cells

The inefficient conversion of lead iodide to perovskite has become one of the major challenges in further improving the performance of perovskite solar cells fabricated by the two‐step method. Herein, the discontinuous lead iodide layer realized by introduction of a polyfluorinated organic diammonium salt, octafluoro‐([1,1′‐biphenyl]‐4,4′‐diyl)‐dimethanaminium (OFPP) iodide which does not form low‐dimensional perovskites, can enable the satisfactory conversion of lead iodide into perovskite, leading to meliorated crystallinity and enlarged grains in the OFPP modulated perovskite (OFPP‐PVK) film. Combined with the effective defect passivation, the OFPP‐PVK films show enhanced charge mobility and suppressed charge recombination. Accordingly, the OFPP‐based perovskite solar cells exhibit a champion efficiency of 24.76 % with better device stability. Moreover, a superior efficiency of 21.04 % was achieved in a large‐area perovskite module (100 cm2). Our work provides a unique insight into the function of organic diammonium additive in boosting photovoltaic performance. Highly efficient and stable perovskite solar cells are developed by incorporating a polyfluorinated organic diammonium salt which cann't generate low‐dimensional perovskites into the lead iodide precursor to change the arrangement of the lead iodide crystals. The resulting high‐quality perovskite film with large grain size boost the efficiencies to 24.70 % and 21.04 % for cell (0.06 cm2) and module (100 cm2), respectively.