CHARGE MOBILITY ALONG THE POLYMER/POLYMER INTERFACE

Abstract

Organic thin-film transistors are increasingly being used in various electronic devices, successfully replacing transistors on silicon and other traditional semiconductors. The advantages of such electronic devices are particularly noticeable in the development of flexible electronic devices. However, one of the intractable problems of organic devices is the low mobility of charge carriers, often not exceeding 10-3 cm2/Vs. Obviously, this significantly limits the scope of their application. In this paper, a new approach to the formation of a transport layer in an organic field-effect transistor is proposed. This approach is based on the use of anomalous transport properties occurring along the interface of two dielectrics. Along such a boundary, a layer of quasi-two-dimensional electron gas with abnormally large values of conductivity and mobility of charge carriers can occur. In this regard, polymer heterostructures representing a field-effect transistor with a transport layer made in the form of an interface between two films of an unconjugated (dielectric) polymer, polydiphenylene phthalide, were investigated in this work. Along such a boundary, a layer of quasi-two-dimensional electron gas with abnormally large values of conductivity and mobility of charge carriers can occur. In this regard, polymer heterostructures representing a field-effect transistor with a transport layer made in the form of an interface between two films of an unconjugated (dielectric) polymer, polydiphenylene phthalide, were investigated in this work. The paper describes the technology of creating a multielectrode device. Polymer films were made by centrifugation from a polymer solution in cyclohexanone. The metal electrodes were manufactured by thermal deposition in vacuum. Measurements of the electrophysical characteristics of an organic field-effect transistor have been carried out. It is established that the main charge carrier along the interface are electrons. Estimates of the mobility of charge carriers were carried out using two different techniques. At zero potential at the gate, an injection model of currents limited by a volumetric charge was used. In the presence of a potential on the gate, the mobility assessment was made within the framework of the field effect model. Comparison of the obtained estimates showed satisfactory agreement of the mobility values. From this fact, it was concluded that it is possible to use an injection model to estimate the mobility of charge carriers when they move along the polymer/polymer interface.