Alleviate the J - V hysteresis of carbon-based perovskite solar cells via introducing additional methylammonium chloride into MAPbI 3 precursor.

The hysteretic phenomenon commonly exists in the J - V curves of perovskite solar cells with different structures, especially for carbon-based mesoscopic perovskite solar cells without hole-conductor (carbon-based PSCs). By adding moderate amounts of methylammonium chloride (MACl) into MAPbI 3 perovskite precursor, we found the J - V hysteresis of carbon-based PSCs could be significantly alleviated and the crystallinity of MAPbI 3 perovskite could also be influenced. With the increasing amount of MACl, MAPbI 3 perovskite showed better and better crystallinity until the MACl came to 0.45 M. The champion device with 0.45 M of additional MACl exhibited a preferable PCE of 14.27% for reverse-scan (RS) and 14.50% for forward-scan (FS), significantly higher than that of the pristine device (8.74% for RS and 4.80% for FS). What's more, the J - V hysteretic index of the device gradually decreased along with the increasing amount of MACl, and kept at low value even when the crystallinity of MAPbI 3 perovskite became poor. Through XRD and PL analysis, we demonstrated that the recombination rate of the accumulated charges at the perovskite/TiO 2 interface is the main reason for photocurrent hysteresis in carbon-based PSCs. High quality of perovskite crystals is an important contributing factor for high-performance PSCs with low hysteresis, but there is no necessary correlation between low hysteresis and good crystallinity. This research presents an effective way to fabricate carbon-based PSCs with low-hysteresis, and at the same time, provides evidence for investigating the origin of J - V hysteresis of PSCs.