Improvement in Performance of Carbon-based Perovskite Solar Cells through Interface Modification with CTAC

Carbon-based perovskite solar cells have attracted much attention, due to their low cost, simple preparation process and high chemical stability. However, the devices exhibit low photoelectric conversion efficiency, owing to the presence of defects and interface impedance between the perovskite active layer and the contact interface. In order to minimize the interfacial defects and improve the charge transfer performance between the perovskite layer and the contact interface, cetyltrimethylammonium chloride (CTAC) was introduced into the lower interface of HTL-free carbon-based perovskite solar cells, because CTAC can be used as interface modification material to passivate the buried interface of perovskite and promote grain growth. It was found that CTAC can not only passivate the interface defects of perovskite, but also improve the crystalline quality of perovskite. As a result, the photovoltaic conversion efficiency of reaches 17.18%, which is 12.5% higher than that of the control group. After 20 days in air with 60% RH humidity, the cell can still maintain more than 90% of the initial efficiency, which provides a new strategy for interfacial passivation of perovskite solar cells.