Wide-bandgap conjugated polymers with a linear naphthacenodithiophene (NDT) donor unit are herein reported along with their performance in both transistor and solar cell devices. The monomer is synthesized starting from 2,6-dihydroxynaphthalene with a double Fries rearrangement as the key step. By copolymerization with 2,1,3-benzothiadiazole (BT) via a palladium-catalyzed Suzuki coupling reaction, NDT-BT co-polymers with high molecular weights and narrow polydispersities are afforded. These novel wide-bandgap polymers are evaluated as the semiconducting polymer in both organic field effect transistor and organic photovoltaic applications. The synthesized polymers reveal an optical bandgap in the range of 1.8 eV with an electron affinity of 3.6 eV which provides sufficient energy offset for electron transfer to PC70BM acceptors. In organic field effect transistors, the synthesized polymers demonstrate high hole mobilities of around 0.4 cm2 V–1 s–1. By using a blend of NDT-BT with PC70BM as absorber layer in organic bulk heterojunction solar cells, power conversion efficiencies of 7.5% are obtained. This value is among the highest obtained for polymers with a wider bandgap (larger than 1.7 eV), making this polymer also interesting for application in tandem or multijunction solar cells. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work was carried out with financial support from BASF. Funding is gratefully acknowledged from Austrian Science Fund (FWF): T578-N19, EC FP7 Project SC2 (610115), EC FP7 Project ArtESun (604397), EPSRC EP/G037515/1, and EPSRC EP/M005143/1. The authors thank Dr. T. Arnold, Diamond Light Source, Didcot, UK and J. Rozbořil, Masaryk University, Brno, Czech Republic for assistance with the GIWAXS-measurements. Financial support from Diamond Light Source is gratefully acknowledged. K. B. gratefully acknowledges financial support from the German Research Foundation (BR 4869/1-1). J. N. acknowledges support from the project CEITEC 2020 (grant No. LQ1601 financed by the MEYS of the Czech Republic).