Efficient Methylamine-Containing Antisolvent Strategy to Fabricate High-Efficiency and Stable FA0.85Cs0.15Pb(Br0.15I2.85) Perovskite Solar Cells.

Antisolvent and additive strategies are significantly positive to improve the crystal quality, device performance, and long-term stability of perovskite solar cells (PSCs). In addition, the high-quality perovskite thin films could be prepared by the methylamine (MA) gas-induced defect-healing process. However, until now, the research on adding MA into the antisolvent, which may take the advantages of two efficiently modified strategies, is still not systematically studied. Here, we add the MA additive into the chlorobenzene antisolvent to fabricate the FA0.85Cs0.15Pb(Br0.15I2.85) films and achieve the high-quality light-absorbing layers with the preferred orientation of (101). The use of an antisolvent, with an appropriate amount of MA in chlorobenzene, leads to extremely uniform and dense perovskite layers with a better hydrophobic performance and enables the fabrication of remarkably improved solar cells with a power conversion efficiency (PCE) of 19.6% for a champion cell. This strategy shows an encouraging improvement of more than 13.95% compared with the traditional antisolvent strategy. The high-efficiency devices could maintain more than 95 or 88% of their initial PCEs after 500 h under continuous light soaking or thermal aging in the dark at 85 °C in a N2-filled glove box, respectively. These results provide an important progress in the realization of highly efficient and stable PSCs.