Title: Synthesis of Ultrathin,Homogeneous Copolymer Dielectrics to Control the Threshold Voltage of OrganicThin-Film Transistors

Author: Kwanyong Pak , Hyejeong Seong , Junhwan Choi , Wan Sik Hwang , and Sung Gap Im^*

Journal: Advanced Functional materials, 2016, Vol.26, p.6574–6582

Abstract

This work demonstrates that thresholdvoltage (V_T) of organicthin-fi lm transistors (OTFTs) can be controlled systematically by introducingnew copolymer dielectrics with electropositive functionality. A series ofhomogeneous copolymer dielectrics are polymerized from two monomers,1,3,5-trimethyl-1,3,5-trivinyl cyclotrisiloxane (V3D3) and 1-vinylimidazole(VI), via initiated chemical vapor deposition. The chemical composition of thecopolymer dielectrics is exquisitely controlled to tune the V_T of C₆₀ OTFTs.In particular, all the copolymer dielectrics demonstrated in this work exhibitextremely low leakage current densities (lower than 2.5 × 10⁻⁸ A cm⁻² at ±3 MV cm⁻¹) even with a thickness less than 23nm. Furthermore, by introducing an ultrathin pV3D3 interfacial layer (about 3nm) between the copolymer dielectrics and C₆₀ semiconductor, thehigh mobility of the C₆₀ OTFTs (about 1 cm² V⁻¹ s⁻¹) remains unperturbed, showing that V_T can be controlled independently by tuning thecomposition of the copolymer dielectrics. Coupled with the ultralow dielectricthickness, the independent V_Tcontrollability allows the V_Tto be aligned near 0 V with sub-3 V operating voltage, which enables asubstantial decrease of device power consumption. The suggested method can beemployed widely to enhance device performance and reduce power consumption invarious organic integrated circuit applications.