Solution-processed organic field-effect transistors (OFETs) have attracted great interest due to their potential as logic devices for bendable and flexible electronics. In relation to n-channel structures, soluble fullerene semiconductors have been widely studied. However, they have not yet met the essential requirements for commercialization, primarily because of low charge carrier mobility, immature large-scale fabrication processes, and insufficient long-term operational stability. Interfacial engineering of the carrier-injecting source/drain (S/D) electrodes has been proposed as an effective approach to improve charge injection, leading also to overall improved device characteristics. Here, it is demonstrated that a non-conjugated neutral dipolar polymer, poly(2-ethyl-2-oxazoline) (PEOz), formed as a nanodot structure on the S/D electrodes, enhances electron mobility in n-channel OFETs using a range of soluble fullerenes. Overall performance is especially notable for (C60 -Ih )[5,6]fullerene (C60 ) and (C70 -D5h(6) )[5,6]fullerene (C70 ) blend films, with an increase from 0.1 to 2.1 cm2 V-1 s-1 . The high relative mobility and eighteen-fold improvement are attributed not only to the anticipated reduction in S/D electrode work function but also to the beneficial effects of PEOz on the formation of a face-centered-cubic C60 :C70 co-crystal structure within the blend films.
Bibliographical noteKAUST Repository Item: Exported on 2021-06-28
Acknowledged KAUST grant number(s): OSR-2018-CARF/CCF-3079, OSR-2019-CRG8-4095
Acknowledgements: S.N. and D.D.C.B. thank the University of Oxford for funding a postdoctoral research fellowship (S.N.) and laboratory facilities at the Clarendon Laboratory. D.D.C.B. also thanks the King Abdullah University of Science and Technology (KAUST) for additional support. T.D.A. thanks KAUST Research and the KAUST Solar Centre for funding (award numbers OSR-2018-CARF/CCF-3079 and OSR-2019-CRG8-4095). Y.K. acknowledges ﬁnancial support from the National Research Foundation (NRF) of Korea via grants 2018R1D1A3B07046214 and 2018R1A6A1A03024962. G.T.M. and P.D.N. further acknowledge use of characterization facilities within the David Cockayne Centre for Electron Microscopy, Department of Materials, University of Oxford with financial support from the UK Engineering and Physical Sciences Research Council (EPSRC) via EP/K040375/1 “South of England Analytical Electron Microscope” and EP/M010708/1. Additional instrument provision from the Henry Royce Institute via EP/R010145/1 is also gratefully recorded.
ASJC Scopus subject areas
- Mechanics of Materials
- Materials Science(all)
- Mechanical Engineering