A new strategy for constructing a dispiro-based dopant-free hole-transporting material: spatial configuration of spiro-bifluorene changes from a perpendicular to parallel arrangement

Zhongquan Wan; Jinyu Yang; Jianxing Xia; Hongyu Shu; Xiaojun Yao; Junsheng Luo; Chunyang Jia

doi:10.1039/d1sc01416a

A new strategy for constructing a dispiro-based dopant-free hole-transporting material: spatial configuration of spiro-bifluorene changes from a perpendicular to parallel arrangement

Chem Sci. 2021 May 13;12(24):8548-8555. doi: 10.1039/d1sc01416a.

Authors

Zhongquan Wan¹, Jinyu Yang¹, Jianxing Xia¹, Hongyu Shu¹, Xiaojun Yao², Junsheng Luo¹, Chunyang Jia¹

Affiliations

¹ State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Electronic Science and Engineering, University of Electronic Science and Technology of China Chengdu 610054 China zqwan@uestc.edu.cn cyjia@uestc.edu.cn.
² State Key Laboratory of Applied Organic Chemistry, Lanzhou University Lanzhou 730000 China.

Abstract

Due to the low intrinsic hole mobility caused by the orthogonal conformation of two fluorene units in Spiro-OMeTAD which is a classic hole-transporting material (HTM) in perovskite solar cells (PSCs), Spiro-OMeTAD based PSCs generally can only obtain high performances through a sophisticated doping process with dopants/additives, which adds to the cost and complicacy of device fabrication, and also adversely affects the stability of PSC devices. Herein, a novel dispiro-based HTM, WH-1, is designed by cleverly replacing the central carbon atom of Spiro-OMeTAD with cyclohexane, and the spatial configuration of the HTM is changed from vertical orthogonality of the two fluorene units to a parallel arrangement, which is beneficial for the formation of a homogeneous and compact HTM film on the surface of the perovskite film, improvement of intermolecular electronic coupling and intrinsic hole mobility. WH-1 is obtained by two-step facile synthesis with a high yield from commercially available materials. WH-1 is used in PSCs as a dopant-free HTM, which is the first time that the dispiro-based molecule has been applied as a dopant-free HTM, and a power conversion efficiency (PCE) of 19.57% is obtained, rivaling Li-TFSI/t-BP doped Spiro-OMeTAD in PCE (20.29%), and showing obvious superior long-term stability.