Dipoles with donor-π-acceptor structure inhibit ion migration to improve the efficiency and stability of inverted perovskite solar cells

Organic-inorganic hybrid perovskites (PVK) have aroused big enthusiasm of many researchers due to their excellent photoelectric properties. However, PVK films always inevitability demonstrate large number of defects, thus greatly affect the performance and stability of the device. Many parts of the defects are aroused from ion migrations because of the weak antibonding between Pb and I. Here, we use 4-Amino-3,5-difluorobenzonitrile (AFBN) to regulate the light-absorbing layer of perovskite films. The AFBN molecules with donor-π-acceptor (D-π-A) structure can simultaneously interact with MA+/Pb2+ cations and I- anions in PVK, which can validly inhibit ion migration and effectively restrain non-radiative recombination, thus improves the photoelectric performance of inverted perovskite solar cells (i-PSCs). The AFBN-based device achieved a champion efficiency of 18.55 %, which is a high PCE for inverted PSCs with simple structure of FTO/NiOx/perovskite/PCBM/BCP/Ag and for devices with relatively high band gap of 1.62 eV, while the control one only shows an efficiency of 16.37 %. Meanwhile, the modified devices demonstrate excellent humidity stability. This work provides a new path for dipoles with donor-π-acceptor structure to inhibit ion migrations for improved efficiency and stability of reverse PSCs.