Fluoropolymer-Based Polymer Gate Dielectrics for Organic Thin-Film Transistors

摘要

Organic thin-film transistors (OTFTs) have gained huge recent interest in a number of applications. To enable high driving speed and to reduce the charging time of gate capacitors in the device, a high electrical conductance is required. The electrical conductance of a TFT is determined by the product of charge carrier mobility (semiconductor property) and charge carrier density in the channel, governed by the capacitance of the gate dielectric. For organic semiconductors, great improvements have been reported within the last ten years, with carrier mobilities approaching that of amorphous silicon. For gate dielectric, high dielectric capacitance for large electrical conductance of a TFT could be achieved by employing high-k dielectric and/or reducing the thickness of the dielectric film. Several classes of high-k materials have been reported as high capacitance gate di-electric. For organic gate dielectrics, ferroelectric polymers with high dielectric constant are representative examples. For instance, high performance ferroelectric TFTs have been demonstrated, employing poly(vinylidene fluoride/trifluoro-ethylene) ferroelectric copolymer as gate dielectric. Furthermore, low-voltage organic transistors and inverters have also been reported using ultrathin Cytop layer as gate dielectric. Although solution-processed fluoropolymer has shown promise as high capacitance gate dielectric for OTFTs, finding orthogonal solvents for solution-processed organic semiconductor to enable all solution-processed TFTs is of great challenge. To this end, we report the development of robust (insoluble), high-capacitance gate dielectric based on high-k fluoropolymer in this study.