Issue 26, 2016

Novel donor–acceptor polymers containing o-fluoro-p-alkoxyphenyl-substituted benzo[1,2-b:4,5-b′]dithiophene units for polymer solar cells with power conversion efficiency exceeding 9%

Abstract

In this work, a new electron-rich building block, o-fluoro-p-alkoxyphenyl-substituted benzo[1,2-b:4,5-b′]dithiophene (BDT) unit, has been used to construct donor (D)–acceptor (A) conjugated copolymers with electron-deficient units 5,6-difluoro-4,7-di(4-(2-ethylhexyl)-2-thienyl)-2,1,3-benzothiadiazole (C8DTBTff) and 5,6-difluoro-4,7-di(4-hexyl-2-thienyl)-2,1,3-benzothiadiazole (C6DTBTff), named P-o-FBDTP-C8DTBTff (P2) and P-o-FBDTP-C6DTBTff (P3), respectively. The experimental results indicate that the incorporation of fluorine into the ortho-position of the alkoxyphenyl substituted BDT unit can enable its resultant polymer to efficiently tune the energy levels and improve the mobility of the derived bulk heterojunction layer, which results in a much higher power conversion efficiency (PCE) of P2 (8.10%). Moreover, replacing the 2-ethylhexyl chains on the DTBTff unit with hexyl chains can improve the planarity of the conjugated backbone of the polymer, which makes the P3/PC71BM blends exhibit higher carrier mobility than P2/PC71BM. Finally, a PCE of 9.02% for the device of P3 is obtained without any additive treatment, which is the highest value achieved for the widely reported D–A polymers with fluorine substituted BDT as the electron-donor unit in single junction polymer solar cells.

Graphical abstract: Novel donor–acceptor polymers containing o-fluoro-p-alkoxyphenyl-substituted benzo[1,2-b:4,5-b′]dithiophene units for polymer solar cells with power conversion efficiency exceeding 9%

Supplementary files

Article information

Article type
Paper
Submitted
04 May 2016
Accepted
31 May 2016
First published
31 May 2016

J. Mater. Chem. A, 2016,4, 10212-10222

Novel donor–acceptor polymers containing o-fluoro-p-alkoxyphenyl-substituted benzo[1,2-b:4,5-b′]dithiophene units for polymer solar cells with power conversion efficiency exceeding 9%

N. Wang, W. Chen, W. Shen, L. Duan, M. Qiu, J. Wang, C. Yang, Z. Du and R. Yang, J. Mater. Chem. A, 2016, 4, 10212 DOI: 10.1039/C6TA03709G

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