Suppressing the Residual PbI2 and Releasing Residual Stress to Regulate Crystallization of Perovskite Film in MAPbI3 PSCs via Doping Functional L-AA-rGO.

Methylammonium lead iodide (MAPbI3) has been considered as the most influential component to boost the rapid development of perovskite photovoltaic devices during the past decade. However, the volatility of organic compounds (Methylammonium ions) causes excessive residual PbI2 during the fabrication and storage process of MAPbI3 films. The doping of various reduced graphene oxide (L-AA-rGO) is systematically induced into MAPbI3 precursor ink to regulate the crystallization process, resulting in obtaining a high-quality perovskite film. The higher content of oxygen-containing functional groups (carboxyl and hydroxyl) and flexible sp3 skeleton structure is successfully obtained in L-AA-rGO(LT), which is favored to form stable coordination bonds with uncoordinated Pb2+ ions via lone pairs of electrons. Therefore, this functional L-AA-rGO(LT) not only passivates deep-level defects Pb0 with its functional groups, but also absorbs the perovskite lattice structure with its special sp3 carbon network to release its residual stress within the perovskite film. This work provides a new method to develop the efficiency and stability of MAPbI3 perovskite solar cells via doping functional L-AA-rGO.