High capacitance, photo-patternable ion gel gate insulators compatible with vapor deposition of metal gate electrodes

Jae Hong Choi, Yuanyan Gu, Kihyon Hong, Wei Xie, C. Daniel Frisbie, Timothy P. Lodge

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

A facile fabrication route to pattern high-capacitance electrolyte thin films in electrolyte-gated transistors (EGTs) was demonstrated using a photoinitiated cross-linkable ABA-triblock copolymer ion gel. The azide groups of poly(styrene-r-vinylbenzylazide) (PS-N3) end-blocks can be chemically cross-linked via UV irradiation (λ = 254 nm) in the self-assembly of poly[(styrene-r-vinylbenzylazide)-b-ethylene oxide-b-(styrene-r-vinylbenzylazide)] (SOS-N3) triblock copolymer in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]). Impedance spectroscopy and small-angle X-ray scattering revealed that ion transport and microstructure of the ion gel are not affected by UV cross-linking. Using a photoinduced cross-linking strategy, photopatterning of ion gels through a patterned mask was achieved. Employing a photopatterned ion gel as the high-capacitance gate insulator in thin film transistors (TFTs), arrays of TFTs exhibited uniform and high device performance. Specifically, both p-type (poly(3-hexylthiophene)) (P3HT) and n-type (ZnO) transistors displayed high carrier mobility (hole mobility of ∼1.4 cm2/ (V s) and electron mobility of ∼0.7 cm2/ (V s) and ON/OFF current ratio (∼105) at supply voltages below 2 V. This study suggests that photopatterning is a promising candidate to conveniently incorporate high-capacitance ion gels into TFTs in the fabrication of printed electronics.

Original languageEnglish (US)
Pages (from-to)19275-19281
Number of pages7
JournalACS Applied Materials and Interfaces
Volume6
Issue number21
DOIs
StatePublished - Nov 12 2014

Keywords

  • chemical cross-linking
  • ion gel
  • metal gate electrode
  • photopatterning
  • thin-film transistor

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