Efficient inverted planar formamidinium lead iodide perovskite solar cells via a post improved perovskite layer

摘要

Formamidinium lead iodide (FAPbI(3)) is a more promising broader absorption material than methylammonium lead iodide (MAPbI(3)) for perovskite solar cells (PSCs). However, in most cases the power conversion efficiencies (PCE) of FAPbI(3) based inverted planar PSCs are still lower than those of MAPbI(3) ones due to the inferior morphology of FAPbI(3) film. In this paper, we demonstrate an optimised formamidinium iodide/isopropyl alcohol (FAI/IPA) modification procedure to improve the photoactive layer for efficient inverted planar FAPbI(3) PSCs. The results show that there is an obvious improvement in open circuit voltage, short current density (JSC), and fill factor (FF). Finally, the best PCE of 14.00% with a JSC of 21.75 mA cm(-2) and a FF of 0.78 was achieved in low-temperature solution-processed PSCs, which represents a more than 40% enhancement in PCE over that of the PSCs without surface modification. Moreover, the devices exhibit good reproducibility and excellent stability. The simple FAI/IPA modification on the photoactive layer can greatly improve planar FAPbI(3) based device performance, which can be a good choice for practical applications.