Issue 10, 2019

Ultra-narrow bandgap non-fullerene acceptors for organic solar cells with low energy loss

Abstract

Two ultra-narrow bandgap non-fullerene acceptors (NFAs), 4TO-T-4F and 4TO-Se-4F, were designed and synthesized for application in organic solar cells (OSCs). Thiophene and selenophene were used as π-spacers to extend the effective conjugated length via intramolecular noncovalent O⋯S or O⋯Se interactions and lower the bandgap. Both NFAs, 4TO-T-4F and 4TO-Se-4F, showed strong absorbance in the range of 700–1000 nm in the near-infrared region with an ultra-narrow bandgap of ∼1.30 and ∼1.27 eV, respectively. Using polymer PTB7-Th as the donor, which has complementary absorption and matched energy levels with these NFAs, the optimized device based on PTB7-Th:4TO-T-4F exhibited a PCE of 8.87%, with a low energy loss of 0.55 eV; and the PTB7-Th:4TO-Se-4F-based OSC device gave a PCE of 7.4%, with a low energy loss of 0.57 eV. Our results indicate that increasing the effective conjugate length of the molecular backbone, thus improving the electron-donating ability of the donor unit in NFAs via noncovalent O⋯S or O⋯Se interactions, is an efficient strategy to design and synthesize ultra-narrow bandgap NFAs for OSCs with low energy loss.

Graphical abstract: Ultra-narrow bandgap non-fullerene acceptors for organic solar cells with low energy loss

Supplementary files

Article information

Article type
Research Article
Submitted
06 ⵖⵓⵛ 2019
Accepted
24 ⵖⵓⵛ 2019
First published
26 ⵖⵓⵛ 2019

Mater. Chem. Front., 2019,3, 2157-2163

Ultra-narrow bandgap non-fullerene acceptors for organic solar cells with low energy loss

D. Liu, T. Wang, X. Ke, N. Zheng, Z. Chang, Z. Xie and Y. Liu, Mater. Chem. Front., 2019, 3, 2157 DOI: 10.1039/C9QM00505F

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