Efficient and Stable Large Bandgap MAPbBr3 Perovskite Solar Cell Attaining an Open Circuit Voltage of 1.65 V

We report on the preparation of MAPbBr3 perovskite films of high electronic quality by applying a methylamine (MA) vapor treatment and mitigating surface defects using the amphiphilic molecular passivator, neopentylammonium chloride (NPACl). We find that post-treatment of MAPbBr3 with methylamine (MA) vapor effectively smooths the surface of the perovskite, eliminating unwanted corrugations and producing phase-pure pinhole free films. The subsequent coating of MAPbBr3 with NPACl eliminates deleterious surface states that act as electron–hole recombination centers while enhancing the resilience of the perovskite solar cell (PSC) against heat stress and ambient moisture, with solid state NMR demonstrating their atomic-scale interaction. As a result, we achieve an unprecedented Voc of 1.65 V which is a record level for mesoporous single junction PSCs together with a power conversion efficiency (PCE) of over 10% in standard AM 1.5 sunlight. The PSC also retains 91.3% of its initial performance after 1100 h of light soaking under full sunlight and at 60 °C while maintaining the device at maximum power point. In contrast, the pristine PSC maintained only 34% of its initial efficiency under the same aging conditions.