N → B Ladder Polymers Prepared by Postfunctionalization: Tuning of Electron Affinity and Evaluation as Acceptors in All-Polymer Solar Cells

Markus Grandl, Jonas Schepper, Sudeshna Maity, Andreas Peukert, Elizabeth Von Hauff*, Frank Pammer

*Corresponding author for this work

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A poly(biphenylene-pyrazinylene) (PPz, E g opt = 3.10 eV) and a head-to-tail regioregular polypyridine (rr-P4Py, E g opt = 3.25 eV) equipped with 1-alkenyl side chains have been prepared and postfunctionalized by hydroboration with different hydroboranes (9H-BBN, (C 6 F 5 ) 2 B-H (BPF-H), Cl 2 B-H) to give the corresponding ladder polymers featuring intramolecular coordinative N → B bonds. Characterization of the optical and electrochemical properties of the postfunctionalized polymers shows that the borylation strongly increases their electron affinity and lowers the optical gaps. Electron affinities between -3.75 eV (PPzBBN, E g opt = 2.16 eV) and -4.35 eV (PPzBPF, E g opt = 2.07 eV) can be reached for hydroborated PPz, while rr-P4Py-derivatives reach LUMO levels of -3.45 eV (P4PyBBN, E g opt = 2.88 eV), -3.85 eV (P4PyBPF, E g opt = 2.95 eV), and -4.15 eV (P4PyBCl 2 , E g opt = 2.95 eV). The potential of this class of compounds as electron acceptors is demonstrated by the investigation of the semiconducting properties of PPzBBN and PPzBPF, which showed ambipolar charge transport with hole and electron mobilities in order of 2 × 10 -5 cm 2 V -1 s -1 . The polymers were tested as acceptors in all-polymer solar cells, which yielded functioning devices, with open-circuit voltages that directly reflect the electron affinity of the employed acceptor.

Original languageEnglish
Pages (from-to)1013-1024
Number of pages12
Issue number3
Early online date24 Jan 2019
Publication statusPublished - 12 Feb 2019


*(E.v.H.) E-mail: e.l.von.hauff@vu.nl. *(F.P.) E-mail: frank.pammer@uni-ulm.de. ORCID Elizabeth von Hauff: 0000-0002-6269-0540 Frank Pammer: 0000-0002-3869-0196 Author Contributions M.G., J.S., and S.M. contributed equally. Funding The authors thank the German Chemical Industry Fund (FCI, Liebig Scholarship to F.P. and doctoral scholarship to M.G.) the German Science Foundation (DFG), and The Netherlands Organization for Scientific Research (NWO) for funding for financial support (V0714M-13MV60 to E.v.H.). Notes The authors declare no competing financial interest.

FundersFunder number
German Chemical Industry Fund
German Science Foundation
Netherlands Organization for Scientific Research
Five Colleges
Deutsche Forschungsgemeinschaft
Nederlandse Organisatie voor Wetenschappelijk OnderzoekV0714M-13MV60


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