He Zhangwei, Li Minghua, Jia Haoran, Yu Runnan, Zhang Yuling, Wang Ruyue, Dong Yiman, Liu Xiangyang, Xu Donghui, Tan Zhan'ao
Beijing Advanced Innovation Center for Soft Matter Science and Engineering, College of Chemical Engineering, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, China.
Key Laboratory of Luminescence and Optical Information, Ministry of Education, School of Physical Science and Engineering, Beijing JiaoTong University, Beijing, 100044, China.
Adv Mater. 2023 Dec;35(51):e2304918. doi: 10.1002/adma.202304918. Epub 2023 Nov 7.
The unavoidably positively and negatively charged defects at the interface between perovskite and electron transport layer (ETL) often lead to severe surface recombination and unfavorable energy level alignment in inverted perovskite solar cells (PerSCs). Inserting interlayers at this interface is an effective approach to eliminate charged defects. Herein, the macrocyclic molecule valinomycin (VM) with multiple active sites of ─C═O, ─NH, and ─O─ is employed as an interlayer at the perovskite/ETL contact to simultaneously eliminate positively and negatively charged defects. Combined with a series of theoretical calculations and experimental analyzes, it is demonstrated that the ─C═O and ─O─ groups in VM can immobilize the uncoordinated Pb to manage the positively charged defect and the formation of N─H···I hydrogen bonding can recompense the formamidine vacancies to eliminate the negatively charged defect. In addition, the VM interlayer induces a favorable downshift band bending at the perovskite/ETL interface, facilitating charge separation and boosting charge transfer. Thanks to the reduced charged defects and favorable energy level alignment, the fabricated inverted PerSC delivers an outstanding power conversion efficiency of 24.06% with excellent long-term ambient and thermal stability. This work demonstrates that managing charged defects via multiple functional groups and simultaneously regulating energy level alignment is a reliable strategy to boost the performance of PerSCs.
钙钛矿与电子传输层（ETL）界面处不可避免地存在带正电和负电的缺陷，这常常导致倒置钙钛矿太阳能电池（PerSCs）中严重的表面复合以及不利的能级排列。在该界面插入中间层是消除带电缺陷的有效方法。在此，具有多个-C═O、-NH和-O-活性位点的大环分子缬氨霉素（VM）被用作钙钛矿/ETL接触处的中间层，以同时消除带正电和负电的缺陷。结合一系列理论计算和实验分析表明，VM中的-C═O和-O-基团可以固定未配位的Pb以处理带正电的缺陷，并且N─H···I氢键的形成可以补偿甲脒空位以消除带负电的缺陷。此外，VM中间层在钙钛矿/ETL界面处诱导出有利的向下能带弯曲，促进电荷分离并增强电荷转移。由于带电缺陷减少和能级排列有利，所制备的倒置PerSC具有24.06%的出色功率转换效率以及优异的长期环境和热稳定性。这项工作表明，通过多个官能团管理带电缺陷并同时调节能级排列是提高PerSCs性能的可靠策略。
