A Trifluoroethoxyl Functionalized Spiro-Based Hole-Transporting Material for Highly Efficient and Stable Perovskite Solar Cells

作者：Zhang, Zheng; Yuan, Ligang; Li, Bin; Luo, Huiming; Wang, Sijing; Li, Zhijun; Xing, Yifan; Wang, Jiarong; Dong, Peng; Guo, Kunpeng^*; Wang, Zhongqiang; Yan, Keyou^*

来源：Solar RRL, 2022, 6(2): 2100944.

DOI：10.1002/solr.202100944

• hole transport materials
• perovskite solar cells
• Spiro-4TFETAD
• stability
• trifluoroethoxy substituents

It is crucial to finely optimize the properties of hole transport materials (HTMs) to improve the performance and stability of perovskite solar cells (PSCs). Herein, a new spiro-based HTM (Spiro-4TFETAD) is developed by replacement of partial methoxy groups in Spiro-OMeTAD with trifluoroethoxy substituents. Spiro-4TFETAD has lower highest occupied molecular orbital level, higher thermal stability (Tg = 140 degrees C), hole mobility (2.04 x 10(-4) cm(2) V-1 s(-1)), and better hydrophobicity with respect to Spiro-OMeTAD. The PSCs using Spiro-4TFETAD achieve a power conversion efficiency of 21.11% and excellent humidity resistance. It maintains an average 83% of their initial power conversion efficiency values even in high relative humidity of 60% without encapsulation and 82% of its initial performance after 100 h continuous illumination at the maximum power point. The superior performance underscores the promising potential of the trifluoroethoxyl molecular design in preparing new HTMs toward highly efficient and stable PSCs.