Highly-Stable Organo-Lead Halide Perovskites Synthesized Through Green Self-Assembly Process

Although unprecedented conversion efficiency has been achieved in organic-inorganic hybrid perovskite solar cells (PSCs), their long-term stability has remained a major issue in their transition. Here, we demonstrate a highly-stable CH3NH3PbI3 (MAPbI(3)) perovskite using a green self-assembly (SA) process that provides a major breakthrough in resolving this issue. In this process, the hydrophobic polymer, poly(methyl methacrylate) (PMMA), is introduced into the 2D layered MAPbI(3) perovskite intermediates, resulting in chemical coordination and self-assembly into 3D perovskite grains with PMMA coated along the grain boundaries. The bilayer grain boundary effectively blocks moisture corrosion thereby significantly improving the stability of MAPbI(3) perovskite. Further, PMMA is found to reduce the trap density by electronically compensating the iodide vacancy along the boundary, which decreases the charge recombination and improves the open circuit voltage of PSCs. The PSCs comprising the MAPbI(3)-PMMA layer show excellent stability under high moisture conditions, exhibiting no phase change under approximate to 70% humidity for over 31 days (approximately 500% higher compared to state-of-the-art) and excellent performance in 50-70% humidity for over 50 days.