Reducing Defects Density and Enhancing Hole Extraction for Efficient Perovskite Solar Cells Enabled by π‐Pb2+ Interactions

• Published in: Angewandte Chemie International Edition 2021-08, Vol.60 (32), p.17356-17361
• Main Authors: Wen, Lirong, Rao, Yi, Zhu, Mingzhe, Li, Ruitao, Zhan, Jingbo, Zhang, Linbao, Wang, Li, Li, Ming, Pang, Shuping, Zhou, Zhongmin
• Format: Article
• Language: English
• Subjects: charge extraction; Defects; defects density; Density functional theory; Doping; Lead; Organic materials; organic small molecule; perovskite solar cells; Perovskites; Photovoltaic cells; Recombination; Solar cells; Work functions; π-Pb2+ interactions
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202102096

Molecular doping is an of significance approach to reduce defects density of perovskite and to improve interfacial charge extraction in perovskite solar cells. Here, we show a new strategy for chemical doping of perovskite via an organic small molecule, which features a fused tricyclic core, showing strong intermolecular π‐Pb2+ interactions with under‐coordinated Pb2+ in perovskite. This π‐Pb2+ interactions could reduce defects density of the perovskite and suppress the nonradiative recombination, which was also confirmed by the density functional theory calculations. In addition, this doping via π‐Pb2+ interactions could deepen the surface potential and downshift the work function of the doped perovskite film, facilitating the hole extraction to hole transport layer. As a result, the doped device showed high efficiency of 21.41 % with ignorable hysteresis. This strategy of fused tricyclic core‐based doping provides a new perspective for the design of new organic materials to improve the device performance. Featuring a fused tricyclic core, an organic small molecule was intentionally synthesized to reduce defects density and improve hole transportation in perovskite devices via π‐Pb2+ interactions, confirmed by multiple characterizations and simulation.