Cage polyamine molecule modulating the buried interface of tin oxide/ perovskite in photovoltaic devices

Molecular modulating have recently emerged as an effectual strategy for ameliorating the performance and stability of perovskite solar cells (PSCs). However, to date cage polyamine with nitrogen heterocyclic porous structure is rarely used as the modulator. Herein, a cage polyamine molecule 1,4-diazabicyclo[2.2.2]octane (DABCO) as modulator is intercalated into the buried interface between electron transport layer and perovskite layer. The situation of the perovskite bottom layer is ascertained by peeling off the buried interfaces. The intercalation of DABCO not only passivates the defect, resulting in a 54 % decrease in trap-state density; but also assists the crystal growth of perovskite, relieves lattice tensile stress; as well as optimizes the energy level alignment of the functional layers. As a result, the DABCO optimized PSC achieves a power conversion efficiency of 23.6 % along with excellent stability, compared to 20.5% for the pristine PSC. The research provides a typical molecular modulating to utilize cage polyamine in PSCs.