The Interface Modification And Performance Research Of The Organic Field Effect Transistor

In recent decades, with the in-depth research of organic electronics, organic filed effect transistor(OFET) which is based on the organic semiconductor as functional materials have a performance reaching to compete with poly silicon’s levels, on this basis, the organic circuit also in rapid development. With optimization design of semiconductor functional materials, effective interface modification, improving the performance of organic field-effect transistor are achieved. At the same time, how to promote the application of semiconductor material from theory to practice is also obtained the widespread attention.This dissertation revolves around how to improve the performance of the organic field effect transistor, by modifying dielectric layer using ink-jet printing method and the design optimization of the different types of semiconductor material, to explore the relationship between structure and performance of the different organic semiconductor condensed materials. The main results are obtained as follows:The tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) is a well-known C-T complex as the first organic metal. Thanks to its excellent conductivity, this complex salt was mainly applied by physicists as electrodes. In this dissertation a novel application of TTF-TCNQ inorganic electronics as a buffer layer is discussed. The average thickness of the ink-jet printed TTF-TCNQ nanoweb was about 2 nm. Using this buffer layer, some devices were fabricated using pentacene, tetracene and copper(Ⅱ) phthalocyanine(CuPc). Under the same conditions, the mobility increased as high as several tens of times higher than the devices fabricated on the n-octadecyl triethoxysilane(OTS) modied SiO2, without reduction of the on/off ratio.Seven kinds of diphenylethylene biphenyl compounds were designed and synthesized, as activity semiconductor layer to construct the field effect transistor devices, testing their device performance. We found that most devices have good air hole mobility and stability, and further explore the relationship between the film morphology and performance of this materials. By comparing the different substituents affect π-electron cloud overlap or spatial configuration of molecules and the morphology of polycrystalline thin films, we found the affects the transmission efficiency of carrier. The impact of thin film growth temperature on device performance and the morphology results are basically identical. The performance is improved as the larger of grain and the less of grain boundary.Five kinds of diphenylethylene phenyl materials were adopted as function to construct the field effect transistor and test their performance. By comparing the influence of different substituent on device performance, we found:when the substituent is electronic-strengthen group, strengthen the molecular electron cloud density, the transmission efficiency of carrier and device performance is improved. When the substituent is electron-withdrawing groups, reducing the transmission efficiency of carrier, performance is degradated. Mobility of the device is impacted by the film morphology, molecular electronic structure and molecular stack together.