The Evolution of Classical Spiro-OMeTAD: Synthesis of Arylamine Endcapped Indenone Spirofluorene

Shihui Liu; Xiaoqing Yi; Hao Wang; Tao Ye; Kui Wang; Wei Cao; Jing Guan; Ruiqing Fan; Yulin Yang; Sue Hao; Debin Xia

doi:10.3389/fchem.2022.898320

The Evolution of Classical Spiro-OMeTAD: Synthesis of Arylamine Endcapped Indenone Spirofluorene

Front Chem. 2022 May 31:10:898320. doi: 10.3389/fchem.2022.898320. eCollection 2022.

Authors

Shihui Liu^{1

2}, Xiaoqing Yi², Hao Wang¹, Tao Ye¹, Kui Wang¹, Wei Cao², Jing Guan¹, Ruiqing Fan², Yulin Yang², Sue Hao², Debin Xia^{2

3}

Affiliations

¹ Department of Organic Chemistry, College of Pharmacy, Harbin Medical University, Harbin, China.
² MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, China.
³ State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, China.

Abstract

Spiro-OMeTAD is the well-known hole transporting material (HTM) in perovskite solar cells. In this work, its derivatives, namely four D-A shaped triphenylamine or biphenylamine endcapped indenone spirofluorene (SFD-TPA, SFD-OMeTPA, SFD-TAD, and SFD-OMeTAD), were designed and synthesized. With the introduction of electron-donating moieties and the extension of conjugation length, a series of changes in photophysical and electrochemical properties could be detected. Notably, in comparison with the optical gap (2.96 eV) of the reported spiro-OMeTAD, SFD-OMeTAD presents an optical gap as low as 1.87 eV. Moreover, density functional theory simulations were employed to further investigate their geometric and electronic structures. Finally, steady-state photoluminescence measurements proved the efficient charge separation and collection processes at the perovskite/HTM interface. It can be predicted that all four compounds with enhanced sunlight absorption capability and suitable frontier energy levels can be used as hole-transporting materials for perovskite solar cells.

Keywords: indenone; organic semiconductor; polycyclic aromatic hydrocarbons; spiro-OMeTAD; spirofluorene.