Rational design of Lewis base molecules for stable and efficient inverted perovskite solar cells

• Published in: Science (American Association for the Advancement of Science) Vol. 379; no. 6633; pp. 690 - 694
• Main Authors: Li, Chongwen, Wang, Xiaoming, Bi, Enbing, Jiang, Fangyuan, Park, So Min, Li, You, Chen, Lei, Wang, Zaiwei, Zeng, Lewei, Chen, Hao, Liu, Yanjiang, Grice, Corey R., Abudulimu, Abasi, Chung, Jaehoon, Xian, Yeming, Zhu, Tao, Lai, Huagui, Chen, Bin, Ellingson, Randy J., Fu, Fan, Ginger, David S., Song, Zhaoning, Sargent, Edward H., Yan, Yanfa
• Format: Journal Article
• Language: English
• Published: United States The American Association for the Advancement of Science 17.02.2023; AAAS
• Subjects: Circuits; Crystal defects; Density functional theory; Energy conversion efficiency; Grain boundaries; Interfaces; Lewis base; Perovskites; Phosphorus; Photovoltaic cells; Solar cells; SOLAR ENERGY; Sulfur
• ISSN: 0036-8075; 1095-9203; 1095-9203
• DOI: 10.1126/science.ade3970

Lewis base molecules that bind undercoordinated lead atoms at interfaces and grain boundaries (GBs) are known to enhance the durability of metal halide perovskite solar cells (PSCs). Using density functional theory calculations, we found that phosphine-containing molecules have the strongest binding energy among members of a library of Lewis base molecules studied herein. Experimentally, we found that the best inverted PSC treated with 1,3-bis(diphenylphosphino)propane (DPPP), a diphosphine Lewis base that passivates, binds, and bridges interfaces and GBs, retained a power conversion efficiency (PCE) slightly higher than its initial PCE of ~23% after continuous operation under simulated AM1.5 illumination at the maximum power point and at ~40°C for >3500 hours. DPPP-treated devices showed a similar increase in PCE after being kept under open-circuit conditions at 85°C for >1500 hours. Lewis base molecules that contain electron-donating atoms such as oxygen or sulfur can bind to undercoordinated lead atoms and passivate defects at interfaces and grain boundaries in perovskite films. Li et al . used density functional theory to screen potential Lewis bases and found that phosphorus-containing molecules showed the strongest binding to lead. A small amount of 1,3-bis(diphenylphosphino)propane stabilized inverted perovskite solar cells. The solar cells could maintain a power conversion efficiency of about 23% for more than 1500 hours under open-circuit conditions at 85°C. —PDS A phosphorus-containing Lewis-base molecule passivates and bridges perovskite grain boundaries and interfaces.