FAPbI3-nanoparticles with ligands act synergistically in absorbent layers for high-performance and stable FAPbI3 based perovskite solar cells

The performance of perovskite solar cells (PSCs) depends on the quality of the perovskite absorber layer. In this study, oleic acid (OA) and oleylamine (OAm) ligand-capped formamidinium lead iodide (FAPbI 3 ) nanoparticles (NPs) were incorporated into the formamidinium iodide (FAI) solution, which is one of the precursors for the sequential deposition of the FAPbI 3 layer. The synergistic effect of the FAPbI 3 -NPs and the capped ligand substantially improves the crystallinity, uniformity, and morphology of the bulk FAPbI 3 perovskite films. The enhancements lead to a reduction in charge recombination and a boost in charge transfer efficiency, enabling the optimized PSCs to achieve a remarkable peak power conversion efficiency (PCE) of 25.68 %. Moreover, these PSCs show good stability, with unencapsulated devices maintaining 93 % of the peak performance under ambient air (RH 50 %) for 1000 hours. • Incorporation of FAPbI 3 -nanoparticles (NPs) into FAI solution for sequential deposition of FAPbI 3 perovskite solar cells. • FAPbI 3 -NPs with oleylamine and oleic acid ligands help grow high-quality FAPbI 3 bulk film and redistribute excess surface PbI 2 . • Devices incorporating FAPbI 3 -NPs exhibit a remarkable PCE of 25.68 %, setting a record for perovskite-NPs incorporated into bulk perovskite. • Unencapsulated devices with FAPbI 3 -NPs maintain 93 % of their peak performance in ambient air (RH 50 %) for 1000 hours.