Efficiency improvement of perovskite solar cell utilizing cystamine dihydrochloride for interface modification

The interfacial engineering is a significant strategy for promoting the photovoltaic performance of perovskite solar cell (PSC). In this paper, we demonstrate a simple but effective method to reduce the defects by intercalating the cystamine dihydrochloride (CMDR) at the interface between the electron transport layers (ETLs) and perovskite layer (PVK). The CMDR possesses double amino groups, which can produce Ti-N bonds to combine with TiO2 for decreasing the interface defects, and react with I- ions for suppressing the excess PbI2. XRD and SEM confirm that CMDR significantly improve the crystallinity of PVK. The photoelectrical characterization presents that CMDR modified PSCs exhibit higher conductivity, lesser surface defects, better energy level matching, and superior electron's extraction and transmission than those of pristine devices. Ultimately, the power conversion efficiency of champion PSC is increased from 18.41% to 20.63% with excellent reproducibility.