Fluoroelastomer encapsulation for enhanced reliability of solution-processed carbon nanotube thin-film transistors

Abstract

Single-walled carbon nanotube (SWCNT) has attracted considerable attention as a promising semiconducting material due to its high field-effect mobility, high current-carrying capability, and superior mechanical durability. However, SWCNT-based thin-film transistors (SWCNT-TFTs) generally show insufficient electrical reliability in terms of the drain-current hysteresis and threshold voltage shift under the bias stress. To facilitate the great advantages of SWCNT in commercial electronic devices, strategies are required for enhancing the electrical reliability of SWCNT-TFTs without compromising their mechanical flexibility. In this work, we demonstrate solution-processed, hysteresis-free, and bias-stable SWCNT-TFTs encapsulated with elastomeric poly(vinylidene fluoride-co-hexafluoropropylene) (e-PVDF-HFP) using a lamination method. The dipolar nature of e-PVDF-HFP suppresses the charge trapping, resulting in elimination of hysteresis as well as enhancement of field-effect mobility and subthreshold slope. The bias instability under the negative gate bias stress is also alleviated because the hydrophobic encapsulation layer can exclude physisorbed water/oxygen molecules on the hydrophilic surface. Besides, our solvent-free lamination method effectively prevents the potential damages of the active and electrode layers from the use of the solvents. The proposed encapsulation method with laminating the e-PVDF-HFP film can provide a possibility for realization of wearable applications based on highly reliable solution-processed SWCNT-TFT.