Constructive molecular configurations for surface-defect passivation of perovskite photovoltaics

• Published in: Science (American Association for the Advancement of Science) Vol. 366; no. 6472; pp. 1509 - 1513
• Main Authors: Wang, Rui, Xue, Jingjing, Wang, Kai-Li, Wang, Zhao-Kui, Luo, Yanqi, Fenning, David, Xu, Guangwei, Nuryyeva, Selbi, Huang, Tianyi, Zhao, Yepin, Lee Yang, Jonathan, Zhu, Jiahui, Wang, Minhuan, Tan, Shaun, Yavuz, Ilhan, Houk, Kendall N., Yang, Yang
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 20.12.2019; The American Association for the Advancement of Science; AAAS
• Subjects: Amino groups; Binding; Caffeine; Carbonyl compounds; Carbonyls; Configurations; Defects; Efficiency; Energy conversion efficiency; Functional groups; Hydrogen; Hydrogen bonding; Hydrogen bonds; Iodides; Iodine; Lead; Metal halides; Optimization; Organic chemistry; Passivity; Perovskites; Photovoltaic cells; Photovoltaics; Recombination; Solar cells; SOLAR ENERGY; Surface charge; Surface defects; Theophylline
• ISSN: 0036-8075; 1095-9203; 1095-9203
• DOI: 10.1126/science.aay9698

Surface trap–mediated nonradiative charge recombination is a major limit to achieving high-efficiency metal-halide perovskite photovoltaics. The ionic character of perovskite lattice has enabled molecular defect passivation approaches through interaction between functional groups and defects. However, a lack of in-depth understanding of how the molecular configuration influences the passivation effectiveness is a challenge to rational molecule design. Here, the chemical environment of a functional group that is activated for defect passivation was systematically investigated with theophylline, caffeine, and theobromine. When N-H and C=O were in an optimal configuration in the molecule, hydrogen-bond formation between N-H and I (iodine) assisted the primary C=O binding with the antisite Pb (lead) defect to maximize surface-defect binding. A stabilized power conversion efficiency of 22.6% of photovoltaic device was demonstrated with theophylline treatment.