We report a new high electron affinity acceptor end group for organic semiconductors, 2,1,3-benzothiadiazole-4,5,6-tricarbonitrile (TCNBT). An n-type organic semiconductor with an indacenodithiophene (IDT) core and TCNBT end groups was synthesized by a six-fold nucleophilic substitution with cyanides on a fluorinated precursor, itself prepared by a direct arylation approach. This one-step chemical modification was found to significantly impact the molecular properties: the fluorinated precursor, TFBT IDT, a poor ambipolar semiconductor, was converted into TCNBT IDT, a good n-type semiconductor. The highly electron-deficient end group TCNBT dramatically decreased the energy of the highest occupied and lowest unoccupied molecular orbitals (HOMO/LUMO) compared to the fluorinated analogue and improved the molecular orientation when utilized in n-type organic field-effect transistors (OFETs). Solution-processed OFETs based on TCNBT IDT exhibited a charge carrier mobility of up to µ e ≈ 0.15 cm 2 V -1 s -1 with excellent ambient stability for 100 hours, highlighting the benefits of the cyanated end group and the synthetic approach.
KAUST Repository Item: Exported on 2020-12-23
Acknowledged KAUST grant number(s): CRG
Acknowledgements: The authors thank the Engineering and Physical Sciences Research Council (EPSRC) (EP/L016702/1 and EP/T028513/1), the Royal Society and the Wolfson Foundation (Royal Society Wolfson Fellowship) for funding. The authors also thank the Global Research Laboratory Program of the National Research Foundation (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2017K1A1A2013153) and the Young
Researchers Program of the NRF funded by the Ministry of Science, ICT & Future Planning (NRF-2018R1C1B6006177). This work was also supported by GIST Research Institute (GRI), RISE grant funded by the GIST in 2020. T.D.A. acknowledges the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under award numbers OSR-2019-CRG8-4095.3, and OSR-2020-CRG8-4095.2. J.L thanks CSEM Brasil for studentship.