Star-Shaped and Fused Electron Acceptors based on C3h -Symmetric Coplanar Trindeno[1, 2-b: 4, 5-b': 7, 8-b'']trithiophene Core for Non-Fullerene Solar Cells

Weijie Wang; Xiaofu Wu; Hao Hang; Hua Li; Yonghong Chen; Qian Xu; Hui Tong; Lixiang Wang

doi:10.1002/chem.201804554

Star-Shaped and Fused Electron Acceptors based on C_3h -Symmetric Coplanar Trindeno[1, 2-b: 4, 5-b': 7, 8-b'']trithiophene Core for Non-Fullerene Solar Cells

Chemistry. 2019 Jan 18;25(4):1055-1063. doi: 10.1002/chem.201804554. Epub 2018 Dec 14.

Authors

Weijie Wang^{1

2}, Xiaofu Wu¹, Hao Hang^{1

3}, Hua Li^{1

2}, Yonghong Chen^{1

3}, Qian Xu⁴, Hui Tong^{1

2}, Lixiang Wang^{1

2}

Affiliations

¹ State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P.R. China.
² University of Science and Technology of China, Hefei, 230026, P.R. China.
³ University of Chinese Academy of Sciences, Beijing, 100049, P.R. China.
⁴ School of Chemistry and Environmental Engineering, Changchun University of Science and Technology, Changchun, 130022, P.R. China.

PMID: 30351501
DOI: 10.1002/chem.201804554

Abstract

Two new star-shaped and fused electron acceptors, TITT-3IC and TITT-3ICF have been designed and synthesized, which consist of a C_3h -symmetric coplanar trindeno[1, 2-b: 4, 5-b': 7, 8-b'']trithiophene (TITT) as the central core and 3-(dicyanomethylidene)indan-1-one and 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene) malononitrile as the peripheral electron-withdrawing groups, respectively. With the large coplanar configuration and electron-rich nature of π-conjugated backbone, these two acceptors exhibit strong intermolecular charge transfer absorption in the region of 500-650 nm with the optical band gaps around 1.9 eV. Relative to TITT-3IC, TITT-3ICF shows the downshifted LUMO level and the slightly redshifted absorption with the higher molar extinction coefficient due to the stronger electron-withdrawing effect of fluorination. When blending with PTB7-Th, the TITT-3ICF-based device displays a higher power conversion efficiency (PCE) of 4.26 % than the TITT-3IC-based device (PCE=3.87 %). Comparing with the TITT-3IC-based device, the increased short circuit current (J_SC ) and fill factor (FF) are responsible for the higher PCE value of the TITT-3ICF-based device, which benefits from its strong and redshifted absorption for light harvesting and proper phase separation morphology for effective exciton dissociation and charge transport. This work demonstrates that as an alternative electron-donating core, TITT will be promising in designing star-shaped non-fullerene materials.

Keywords: C3h-symmetry; donor-acceptor; non-fullerene solar cells; star-shaped electron acceptors; trindeno[1, 2-b: 4, 5-b′: 7,8-b′′]trithiophene.

Abstract

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