Adv. Mater.: Guanidinium-Assisted Surface Matrix Engineering for Highly Efficient Perovskite Quantum Dot Photovoltaics

Title：

Guanidinium-Assisted Surface Matrix Engineering for Highly Efficient Perovskite Quantum Dot Photovoltaics

Authors：

Xufeng Ling,¹ Jianyu Yuan,*¹ Xuliang Zhang,¹ Yuli Qian,¹ Shaik M. Zakeeruddin,² Bryon W. Larson,³ Qian Zhao,³ Junwei Shi,¹ Jiacheng Yang,¹ Kang Ji,¹ Yannan Zhang,¹ Yongjie Wang,¹ Chunyang Zhang,² Steffen Duhm,*¹ Joseph M. Luther,³ Michael Grätzel,*² and Wanli Ma*¹

Institutions：

¹Institute 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

²Laboratory of Photonics and Interfaces (LPI), Institute of Chemical Sciences and Engineering École Polytechnique Fédérale de Lausanne (EPFL), Station 6, Lausanne CH-1015, Switzerland

³Chemistry & Nanoscience Center National Renewable Energy Laboratory, Golden, CO 80401, USA

Abstract：

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 CsPbI₃ 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 CsPbI₃ 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 CsPbBr₃ and FAPbI₃ (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.

IF：

25.809

Link：

https://onlinelibrary.wiley.com/doi/10.1002/adma.202001906