Fabrication And Mechanism Studies Of N-type Organic Field-effect Transistor

In recent years,Organic field-effect transistors(OFETs)have been widely used in flexible electronic devices due to their advantages of low cost,large area preparation,light weight,etc.,and have attracted much attention from researchers.At present,OFET has become one of the core devices in the field of organic electronics and flexible electronics,and is on the edge of commercial production and application.However,there are still some problems to be solved,such as the limited number and performance of n-type organic semiconductor materials,low mobility,poor stability,and unclear structure-performance relationship.This paper mainly aims to improve the performance of n-type OFET devices and study the relationship between structure and performance of n-type organic semiconductor materials.The specific research contents are as follows:(1)Three n-type OFET devices were fabricated based on a series of D-A conjugated polymer(N2200,F-N2200 and Cl-N2200)semiconductors.The absorption spectra showed that the aggregation effect of F-N2200 and Cl-N2200 polymers was enhanced.The substrate and solution were preheated at 150 ? before spinning to reduce the aggregation effect,and then the amorphous semiconductor thin films were obtained.Then,two kinds of OFETs with the structure of BGBC and TGBC were prepared,respectively.Finally,the device performance of different polymer transistors with different structures is compared.(2)The effects of fluorination and chlorination on the energy disorder of OFETs were investigated by measuring the transfer characteristic curves of OFETs at varying temperatures.The information related to energy disorder was extracted by analyzing the data of gate voltage dependent mobility and activation energy.The experimental results show that the fluorination of the main chain can reduce the energy disorder of the semiconductor,which is beneficial to charge transfer,while the chlorination can increase the energy disorder,which is unfavorable to charge transfer.Meanwhile,these phenomena are supported by Density Functional Theory(DFT)calculations.(3)On the basis of the above work,the influence of doping on OFETs devices was further studied by doping method,and the information about energy disorder was further extracted by analyzing the performance of doping devices.The influence of molecular structure on the mobility of the three polymers was explained by considering the effects of fluorination and chlorination on intramolecular transport(mainly due to polarization effect)and intermolecular transport(mainly due to energy disorder).These works are helpful to further understand the mechanism of charge transport of D-A conjugated polymers by fluorination and chlorination,and provide ideas for the further preparation of high-performance n-type OFET devices.