Energy level alignment and defect passivation realized by a dipole molecular bridge for efficient and stable perovskite solar cells

Abstract

The abundant interfacial defects and mismatched energy levels in perovskite solar cells (PSCs) limit their further development. In this work, a dipole molecular bridge is developed by introducing an amphoteric linking molecule called 2-amino-4,5-imidazoledicarbonitrile (AIDCN) at the perovskite/hole transport layer (HTL) interface. Theoretical calculations indicate that AIDCN interacts with the perovskite by forming Pb–N bonds, effectively reducing trap states and inhibiting the formation of localized charges. Meanwhile, the AIDCN dipole molecular bridge improves the uniformity of the surface potential of the perovskite film and achieves a favorable energy level alignment at the perovskite/HTL interface, thereby accelerating charge transport and reducing charge recombination in PSCs. Consequently, the AIDCN-modified PSC achieves a low open circuit voltage loss of 0.34 V and the highest power conversion efficiency of 25.29%, which is higher than that of the control PSCs (22.45%). More importantly, the AIDCN-modified PSC exhibits impressive durability, maintaining 90.92% of its initial efficiency after maximum power point tracking for 1000 h, which is comparable to those of the reported high-stability PSCs. This work presents a new strategy to improve the performance and stability of PSCs by constructing a dipole molecular bridge at the perovskite/HTL interface.