Tailoring morphology and thickness of perovskite layer for flexible perovskite solar cells on plastics: The role of CH3NH3I concentration

A smooth perovskite film fully covering the substrate is of importance for flexible perovskite solar cells (PSCs). In this study, efficient flexible PSCs are fabricated onto conductive plastic substrate by a two-step coating method under ambient condition. By adjusting the concentration of precursor CH 3 NH 3 I (MAI), the morphology and thickness of perovskite layer is effectively tailored, according to SEM and AFM analysis, which consequently gives rise to a thin perovskite layer with smooth surface and smaller grain size. As a result, flexible PSCs with efficiency of 12.7% are prepared under ambient condition, and the excellent mechanical stability of flexible PSCs is also demonstrated with bending test under severe conditions.