Ling Xufeng, Yuan Jianyu, Zhang Xuliang, Qian Yuli, Zakeeruddin Shaik M, Larson Bryon W, Zhao Qian, Shi Junwei, Yang Jiacheng, Ji Kang, Zhang Yannan, Wang Yongjie, Zhang Chunyang, Duhm Steffen, Luther Joseph M, Grätzel Michael, Ma Wanli
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, 199 Ren-Ai Road, Suzhou Industrial Park, Suzhou, Jiangsu, 215123, P. R. China.
Laboratory of Photonics and Interfaces (LPI), Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Station 6, Lausanne, CH-1015, Switzerland.
Adv Mater. 2020 Jul;32(26):e2001906. doi: 10.1002/adma.202001906. Epub 2020 May 25.
Metal halide perovskite quantum dots (Pe-QDs) are of great interest in new-generation photovoltaics (PVs). However, it remains challenging in the construction of conductive and intact Pe-QD films to maximize their functionality. Herein, a ligand-assisted surface matrix strategy to engineer the surface and packing states of Pe-QD solids is demonstrated by a mild thermal annealing treatment after ligand exchange processing (referred to as "LE-TA") triggered by guanidinium thiocyanate. The "LE-TA" method induces the formation of surface matrix on CsPbI QDs, which is dominated by the cationic guanidinium (GA ) rather than the SCN , maintaining the intact cubic structure and facilitating interparticle electrical interaction of QD solids. Consequently, the GA-matrix-confined CsPbI QDs exhibit remarkably enhanced charge mobility and carrier diffusion length compared to control ones, leading to a champion power conversion efficiency of 15.21% when assembled in PVs, which is one of the highest among all Pe-QD solar cells. Additionally, the "LE-TA" method shows similar effects when applied to other Pe-QD PV systems like CsPbBr and FAPbI (FA = formamidinium), indicating its versatility in regulating the surfaces of various Pe-QDs. This work may afford new guidelines to construct electrically conductive and structurally intact Pe-QD solids for efficient optoelectronic devices.
金属卤化物钙钛矿量子点（Pe-QDs）在新一代光伏（PVs）领域备受关注。然而，构建导电且完整的Pe-QD薄膜以最大化其功能仍具有挑战性。在此，通过硫氰酸胍引发的配体交换处理（称为“LE-TA”）后的温和热退火处理，展示了一种配体辅助表面基质策略来调控Pe-QD固体的表面和堆积状态。“LE-TA”方法促使在CsPbI量子点上形成表面基质，该表面基质以阳离子胍鎓（GA⁺）而非SCN⁻为主导，保持了完整的立方结构并促进了量子点固体颗粒间的电相互作用。因此，与对照量子点相比，GA⁺基质限制的CsPbI量子点表现出显著增强的电荷迁移率和载流子扩散长度，在组装成光伏器件时，其最佳功率转换效率达到15.21%，这是所有Pe-QD太阳能电池中最高的之一。此外，“LE-TA”方法应用于其他Pe-QD光伏系统如CsPbBr和FAPbI（FA = 甲脒）时也显示出类似效果，表明其在调控各种Pe-QD表面方面具有通用性。这项工作可能为构建用于高效光电器件的导电且结构完整的Pe-QD固体提供新的指导方针。
