Study On OFETs And Its Integrated Circuits Based On Pentacene And CuPc

Organic electronics have received significant interest in the area of organic RFID, sensors, and lager area displays due to their low cost, flexible, and easy lager area processing. Organic field effect transistor (OFETs) is one of the most important fundamental modules for organic electronics. Recent years, low voltage OFETs, functional OFETs and integrated circuits have attracted much attention. In this thesis, we focused on the research of reduce operating voltage of OFETs; realize functional OFETs and fabrication of organic integrated circuits.1), Reducing operating voltage of OFETs:using ultra thin inorganic insulator layer and modified with organic self assembly monolayer, fabricated OFETs with operating voltage below5V and mobility of1.29cm2V-1s-12), Light effect of OFETs:using Pentacene as semiconductor material, SiO2or OTS/SiO2as insulator, OFETs were fabricated and the light induced hysteresis effect was studied. It is found the light hysteresis window could be tuning by the disorder of semiconductor film, the properties of dielectric layers and the applied electric field. In addtion, we proposed a physical definition and theory model for threshold voltage of OFETs based on the concept of the transport energy with an exponential DOS function. The threshold voltage is fundamental parameter for hysteresis effect and based on the model, a theory model for light induced hysteresis window was proposed and we found that the light hysteresis window is proportional to the charge energy disorder the starting value of the sweeping gate voltage.3), Nonvolatile floating gate OFET memory:nonvolatile floating gate OFET memory devices with light assisted program were studied. Using Pentacene as semiconductor material, gold nanocrystals as charge trapping layer. PMMA as tunneling layer, SiO2as the blocking layer, nano-crystal floating gate OFETs memory devices were fabricated. Through light assisted program, the charge storage capacity of the memory devices are improved to a large extent. The memory window and on/off memory ratio were improved from18V,102to63V,105, respectively.4), Organic rectifier and organic gate circuits which are the most important fundamental modules in organic circuits were studied. The effect of the interface on the electrical characteristics of an organic diode was studied. By modifying Cu bottom electrodes with CuTCNQ, carrier injection barrier and interface contact between metal electrodes and the organic materials were significantly improved. Diodes with pentacene as electro-active functional materials with rectification ratio up to2×106at5V are obtained, and the diode based rectifier circuits show rectification frequencies up to13.56MHz. In addtion, integrated organic rectifier combined with organic diode and capacitor was proposed. The integrated organic rectifier shows rectification frequencies up to1MHz in atmospheric Environment. An effective method to fabricate top contact OFETs using photolithographic process was proposed. The top contact OFETs fabricated using photolithographic process have high performance and easy to integrate. We fabricated organic gate circuits include inverters, NAND gate and NOR gate with different methods. Such as:using photolithographic and shadow mask process, with COMS and PMOS circuits configurations, use bottom gate top contact OFETs and top gate OFETs.