Efficient rigid and flexible perovskite solar cells using strongly adsorbed molecules for lattice repair and grain boundary mitigation†

Additives with strong adsorption energies coordinate with lead ions and reduce halogen vacancy defects, leading to a highly ordered atomic arrangement of the lattices and grain boundary mitigation of the perovskite for efficient perovskite solar cells (PSCs). Herein, we demonstrate efficient rigid and flexible PSCs via 1,3,5-triazine-2,4-diamine hydrochloride (TDH) passivation. This molecular passivation improves the perovskite crystallinity by reducing the lattice point vacancy defects, dislocations and distortions of the lattices. It also restrains the formation of small grain crystals by mitigating the grain boundaries. The rigid PSCs yield a PCE of 26.15% with a fill factor (FF) of 85.94%. The flexible PSCs yield a PCE of 24.68% with a FF of 86.07%. Both devices exhibit superior operational stability. This work provides a passivation strategy and valuable insights for crystalline perovskite materials and high-performance PSCs.