Development of High-k Polymer Materials for Use as a Dielectric Layer in the Organic Thin-Film Transistors

Abstract

In this article, we developed a series of novel high dielectric polymers based on 5-TPM-co-HEMA-co-GMA (TP) and 5-CTPM-co-HEMA-co-GMA (TP−CN) containing alkylated terphenyl and alkylated terphenyl with a cyano group, respectively. These organic insulating materials provide smooth surface topographies, lower leakage current densities (<6 × 10 −7 A/cm 2 at 2 MV/m), and small dielectric loss (<0.02, 10 3 to 10 5 Hz), which display excellent insulating properties. Simultaneously, two kinds of polymer films have higher dielectric constants of 6.8 and 8.6 than other dielectric constants reported in some literatures and most commercial organic dielectric materials. To investigate the potential of TP and TP−CN as gate dielectrics, we successfully prepared bottom-gate top-contact organic thin-film transistors, with para-hexaphenyl (p-6P) as the buffer layer and vanadyl phthalocyanine (VOPc) as the active layer, which yields a higher charge carrier mobility of 0.52 cm 2 V −1 s −1 and on/off ratio > 10 4 .

Optimization of Alkyl Side Chain Length in Polyimide for Gate Dielectrics to Achieve High Mobility and Outstanding Operational Stability in Organic Transistors

“…In addition, WAXD patterns of 30 nm VOPc grown on p -6P films (Figure f) contain almost the same highly crystallized peaks; this further supports the important effects of alkyl side chain modification on the p -6P template monolayer, which primarily optimizes the first few layers of VOPc, resulting in significantly improved performance. It is worth mentioning that the operating voltage of about −40 V of alkyl chains PI was lower than the previous reports, ,, which is −50 V. The lower operating voltage is obtained due to the PI containing long alkyl side chains, enabling optimized grain size and molecular orientation of the semiconductor so that their application as gate dielectrics to other OTFTs has the potential to achieve lower operating voltages and high mobility.…”

Large-Area Flexible Printed Thin-Film Transistors with Semiconducting Single-Walled Carbon Nanotubes for NO2 Sensors

“…The second one is the solution-process method. Printed TFTs with high on/off ratios and low operation voltages could be obtained when using high- k polymer dielectrics such as poly­(vinylidenefluoride trifluoroethylene) P­(VDF-TrFE) or high-capacitance electrolytes as the dielectric inks. , Unfortunately, these devices exhibited large hysteresis for P­(VDF-TrFE) TFT devices and poor bias stress stability for high-capacitance electrolyte TFT devices. Using thermal oxidation or oxygen plasma treatment to form ultrathin metal oxide dielectric layers above active metals [aluminum (Al) and yttrium (Y)] is the third way, which is a large-area, simple, and low-cost method to prepare the dielectric layers (especially for the preparation of AlO x ). , Some groups have ever tried to use ultrathin aluminum oxide dielectric layers produced by oxygen plasma or room-temperature oxidation to fabricate the solution-processable or printed TFTs. ,− Unfortunately, these TFT devices showed high leakage currents up to 10 –8 A.…”

Organic field-effect transistors with low-temperature curable high-k hybrid gate dielectrics

“…PVDF [12] and its copolymers have high k, but have the disadvantages of severe hysteresis behavior and a rough dielectric surface, so they are usually used only for nonvolatile memory applications [13]. Synthesis approaches have also been demonstrated for high-k dielectric matierials [14][15][16][17][18]. Another option is to use cyanyl-substituted natural polymers, such as cynanoethylated pullulan, which is suitable for e scalable production at low cost.…”