Efficient rigid and flexible perovskite solar cells with 86% fill factor using multifunctional electron-enriched molecular passivation

Multiple active sites of additives with strong adsorption energies adsorb on perovskite facets, coordinate with lead ions and reduce halogen vacancy defects, leading to a highly ordered atomic arrangement of grain boundaries for efficient perovskite solar cells (PSCs). Herein, we demonstrate efficient rigid and flexible PSCs via 1,3,5-triazine-2,4-diamine hydrochloride (TDH) molecular passivation. The TDH treatments restrain a formation of small twin crystals and remarkably improve the crystallinity through reducing the aligned point vacancy defects on the perovkite lattices, and the dislocations and distortions across the boundaries in the perovkite crystals. The rigid PSCs yield high PCE of 26.15% with fill factor (FF) as high as 85.94% (maximum: 86.03%). The flexible PSCs yield high PCE of 24.68% with FF as high as 86.07%. Both efficient rigid and flexible PSCs without package exhibit superior operation stability. The work provides an effective passivation strategy and valuable insights for crystalline perovskite materials and high-performance rigid and flexible PSCs.