Tailoring the Grain Boundaries of Wide-Bandgap Perovskite Solar Cells by Molecular Engineering

Due to the attraction of fabricating highly efficient tandem solar cells, wide-bandgap perovskite solar cells (PSCs) have attracted substantial interest in recent years. However, polycrystalline perovskite thin-films show the existence of trap states at grain boundaries which diminish the optoelectronic properties of the perovskite and thus remains a challenge. Here, a one-step solution-processing of [MA0.9Cs0.1Pb(I0.6Br0.4)3]wide-bandgap perovskite using phenylhydrazine iodide with amino groups is demonstrated to successfully passivate the trap density within grain boundaries and increase the perovskite grain size. The reinforced morphology and grain boundaries treatment considerably enhanced the power conversion efficiency (PCE) from 12.16% for pristine to 14.63% for the treated devices. This strategy can be easily adopted to other perovskites and help realize highly efficient perovskite solar cells.