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A few-layer molecular film on polymer substrates to enhance the performance of organic devices

Abstract

In organic electronics the functionalization of dielectric substrates with self-assembled monolayers is regarded as an effective surface modification strategy that may significantly improve the resulting device performance. However, this technique is not suitable for polymer substrates typically used in flexible electronics. Here, we report organic modifiers based on a paraffinic tripodal triptycene, which self-assembles into a completely oriented two-dimensional hexagonal triptycene array and one-dimensional layer stacking structure on polymer surfaces. Such few-layer films are analogous to conventional self-assembled monolayers on inorganic substrates in that they neutralize the polymer surface. Furthermore, the triptycene films significantly improve the crystallinity of an organic semiconductor and the overall performance of organic thin-film transistors, therefore enabling the fabrication of high-performance organic complementary circuits on polymer substrates with high oscillation speeds and low operation voltage.

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Fig. 1: Schematic illustrations of the surface functionalization of solid substrates with organic molecules.
Fig. 2: Structural characterization of 30-nm-thick films of DNTT on parylene and triptycene-coated parylene.
Fig. 3: The architecture and properties of DNTT-based OTFTs.
Fig. 4: Characteristics of complementary circuits constructed from OTFTs having a 30-nm-thick parylene dielectric with a few-layer triptycene film.

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Acknowledgements

This work was partly supported by the ‘Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials’ from the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT). The synchrotron GI-XRD experiments were performed at the BL45XU in the SPring-8 with the approval of the RIKEN SPring-8 Center (proposal nos. 20140056, 20150068 and 20160027). M.K. acknowledges funding through the LIT startup Grant LIT013144001SEL. The authors gratefully acknowledge N. Seiki and D. Ordinario for discussions.

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T.Y., R.S., M.K., T.T., and T.Se. fabricated and characterized the transistors and circuits. T.K., Y.S., F.I. and T.F. performed the synthetic experiments and characterized thin films. T.Y., T.K., M.K., Y.S., F.I. and T.F. wrote the manuscript with comments from all authors. T.So. supervised the project.

Corresponding authors

Correspondence to Tomoyuki Yokota, Takanori Fukushima or Takao Someya.

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Supplementary Information

Supplementary Methods, Supplementary Table 1 and Supplementary Figs. 1–13

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Yokota, T., Kajitani, T., Shidachi, R. et al. A few-layer molecular film on polymer substrates to enhance the performance of organic devices. Nature Nanotech 13, 139–144 (2018). https://doi.org/10.1038/s41565-017-0018-6

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