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Issue 9, 2018
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Two-dimensional benzo[1,2-b:4,5-b′]difuran-based wide bandgap conjugated polymers for efficient fullerene-free polymer solar cells

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Abstract

Wide bandgap conjugated polymers are important for providing complementary absorption with the state-of-the-art narrow bandgap nonfullerene electron acceptors to maximise the utilization of solar photons. In this work, two wide bandgap two-dimensional conjugated polymers, PBDFT–Bz and PBDFF–Bz, based on benzo[1,2-b:4,5-b′]difuran building block were designed and synthesized. The optical bandgaps of PBDFT–Bz and PBDFF–Bz were found to be 1.90 eV and 1.85 eV, respectively. PBDFF–Bz with 2-ethylhexylfuryl side chains possesses the lower HOMO energy level and shows denser π–π stacking compared to PBDFT–Bz with 2-ethylhexylthienyl side chains. The fullerene-free PBDFF–Bz:ITIC-based polymer solar cell (PSC) showed a PCE of 9.46% with a Jsc of 15.02 mA cm−2, a Voc of 0.94 V and a FF of 67%; by using m-ITIC as an electron acceptor, the PCE was further improved to 10.28% with an enhanced Jsc of 16.57 mA cm−2, a Voc of 0.94 V and a FF of 66%. Under the same condition, the PBDFT–Bz:m-ITIC device gave a PCE of 9.84% with a Jsc of 16.63 mA cm−2, a Voc of 0.85 V and a FF of 70%. In addition, it is exciting that the PBDFF–Bz based devices show a small energy loss (Eloss) of 0.63 eV, while the PBDFT–Bz based devices show an Eloss of 0.72 eV. These results are among the best for fullerene-free devices with BDF-based polymers, and demonstrate that BDF is a very promising candidate for highly efficient polymer solar cells.

Graphical abstract: Two-dimensional benzo[1,2-b:4,5-b′]difuran-based wide bandgap conjugated polymers for efficient fullerene-free polymer solar cells

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Publication details

The article was received on 15 Dec 2017, accepted on 30 Jan 2018 and first published on 31 Jan 2018


Article type: Paper
DOI: 10.1039/C7TA10976H
Citation: J. Mater. Chem. A, 2018,6, 4023-4031
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    Two-dimensional benzo[1,2-b:4,5-b′]difuran-based wide bandgap conjugated polymers for efficient fullerene-free polymer solar cells

    Y. Gao, Z. Wang, J. Zhang, H. Zhang, K. Lu, F. Guo, Y. Yang, L. Zhao, Z. Wei and Y. Zhang, J. Mater. Chem. A, 2018, 6, 4023
    DOI: 10.1039/C7TA10976H

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