Electrically and thermally stable gate dielectrics from thiol–ene cross-linked systems for use in organic thin-film transistors

Abstract

Novel solution-processable thiol–ene gate dielectrics for use in organic thin-film transistors (OTFTs) have been designed and fabricated in this study. Incorporation of UV-sensitive functional groups in the thiol–ene system affords electrical and thermal stability to the gate dielectric layers by a simple photocuring method. The very smooth thiol–ene gate dielectric layer exhibits excellent insulating properties (leakage current densities ∼10⁻⁷ to 10⁻⁸ A cm⁻² at 2 MV cm⁻¹) and a relatively high dielectric constant (>5) with high environmental stability. Furthermore, the electrical properties of this gate dielectric layer are stable up to 300 °C and show no changes even when the dielectric is kept for 100 days in air; this stability can be attributed to the densely cross-linked structure of the thiol–ene layer. OTFTs utilizing the thiol–ene gate dielectrics with various organic semiconductors show enhanced TFT performances; in particular, they show no hysteresis without a threshold-voltage shift. These observations are in contrast to those for a representative organic gate dielectric polymer, cross-linked poly(4-vinylphenol).