Monolayer-like MAPbI3 film with high charge mobility for solar cells

The monolayer-like perovskite films with single crystal cross profile are considered to be the ideal active layer for high efficiency perovskite solar cells (PSCs) owing to the minimization of defects and maximization of charge carrier mobility. To date, how to prepare a high-quality monolithic perovskite film is still a challenge for PSCs. We have been seeking the combined methods for the monolayer-like MAPbI3 film towards high efficiency solar cells. Recently, we have revealed a colloidal strategy to prepare the compact monolayer-like perovskite films by controlling the size of colloidal clusters in the perovskite precursor. According to the space charge limited current, the trap density in the monolithic film was nearly an order of magnitude lower than that of the control samples, while the charge carrier mobility is approaching to that of MAPbI3 single crystal. As a result, the power conversion efficiency of the PSCs is increased to over 20%. These results shed light on the preparation of high quality monolayer-like MAPbI3 films via retarding crystallization and increasing nucleation rate.