Li Yan, Li Siqi, Shen Yujie, Han Xue, Li Yao, Yu Yingchun, Huang Meilan, Tao Xia
State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China.
School of Chemistry & Chemical Engineering, Queen's University Belfast, Belfast BT9 5AG, U.K.
ACS Appl Mater Interfaces. 2022 Oct 26;14(42):47872-47881. doi: 10.1021/acsami.2c13585. Epub 2022 Oct 12.
Interface engineering mediated by a designed chemical agent is of paramount importance for developing high-performance perovskite solar cells (PSCs). It is especially critical for planar SnO-based PSCs due to the presence of abundant surface defects on SnO and/or perovskite surfaces. Herein, a novel multifunctional agent histidine (abbreviated as His) capable of cross-linking SnO and perovskite is employed to modify the SnO/perovskite interface. Density functional theory (DFT) calculations and experimental results demonstrate that the carboxylate oxygen of His can form a Sn-O bond to fill the oxygen vacancies on the surface of SnO, while its positively charged imidazole ring can occupy the cationic vacancies and its -NH group interacts with the I ion on the perovskite lattice. This cross-linking contributes to the significantly decreased interfacial trap state density and nonradiative recombination loss. In addition, it facilitates electron extraction/transfer and also improves interfacial contact and the quality of perovskite film. Correspondingly, the His-modified device delivers a superior power conversion efficiency (PCE) of 22.91% (improved from 20.13%) and an excellent open-circuit voltage () of 1.17 V (improved from 1.11 V), along with significantly suppressed hysteresis. Furthermore, the unencapsulated device based on His modification shows much better humidity and thermal stability than the pristine one. The present work provides guidance for the design of innovative multifunctional interfacial material for highly efficient PSCs.
由设计的化学试剂介导的界面工程对于开发高性能钙钛矿太阳能电池（PSC）至关重要。对于基于平面SnO的PSC来说尤其关键，因为SnO和/或钙钛矿表面存在大量表面缺陷。在此，一种能够交联SnO和钙钛矿的新型多功能试剂组氨酸（缩写为His）被用于修饰SnO/钙钛矿界面。密度泛函理论（DFT）计算和实验结果表明，His的羧酸根氧可以形成Sn-O键以填充SnO表面的氧空位，而其带正电的咪唑环可以占据阳离子空位，并且其-NH基团与钙钛矿晶格上的I离子相互作用。这种交联有助于显著降低界面陷阱态密度和非辐射复合损失。此外，它促进电子提取/转移，还改善界面接触和钙钛矿薄膜的质量。相应地，His修饰的器件具有22.91%的优异功率转换效率（PCE）（从20.13%提高）和1.17 V的出色开路电压（从1.11 V提高），同时显著抑制了滞后现象。此外，基于His修饰的未封装器件显示出比原始器件更好的湿度和热稳定性。本工作为高效PSC的创新多功能界面材料设计提供了指导。
