Fabraction And Characterization Of Organic Field-effect Transistors Based On Diimide-based Small Molecules

In recent years,with the rapid development of organic electronics,n-type semiconductor materials with high performance and air stability have gradually become a research hotspot.Among them,diimide-based molecules are a kind of common n type organic semiconductor materials.The imide groups in such molecules have strong electron-withdrawing properties,which can effectively improve the electron affinity and air stability ofπ-conjugated systems.In addition,the existence of nitrogen atoms in imide groups can provide active sites for the regulation of molecular properties.Therefore,studying the relationship between structures and properties of such molecules can provide reference value for the design and synthesis of new semiconductor materials.In this paper,a variety of organic field-effect transistors based on diimide-based small molecules were fabricated,and with the usage of a variety of structural characterization methods,the relationship between the structure and the carrier transport performance was explored.1.Single crystals and thin-film filed-effect transistors based on naphthalimide benzothiophene molecules were prepared,and the intrinsic relationship between molecular configuration,packing mode and charge carrier transport was explored.For thin-film field-effect transistors,since the film of anti isomers has better continuity than that of syn isomers,the former shows better device performance.For single-crystal field-effect transistors,the performance of syn isomers is higher than that of anti isomers due to the tighter intermolecular packing of syn isomers.Among them,the mobility of single crystal devices of syn isomers is 0.08 cm² V^-1s^-1,and the mobility of anti isomers is 0.06 cm² V^-1 s^-1.2.Single crystal and thin film field-effect transistors based on bowl-shaped diimide molecules were prepared,and the effect of different substituents on nitrogen atoms on the device performance was explored.The results show that the electron mobility of molecules substituted with alkyl chains is higher than that of molecules containing fluorine as substituents,and the extremely strong interaction between fluorine atoms weaken theπ-πinteraction,so the performances of devices are degraded.Furthermore,an off-center spin-coating method was used to improve the device performance,and the electron mobility of the obtained thin-film device is up to 1.44×10^-2 cm² V^-1 s^-1.3.Thin film transistors based on diimide petal-like molecules were fabricated,and the effects of different isomers on the performance of thin film devices were explored.The results show that due to the different morphologies of the films prepared by the two isomers,as well as the differences in the packing of molecules in the films,the corresponding performances of thin-film devices are different.Among them,the performance of thin-film devices fabricated with the isomer which has tighter molecular packing is higher,and the electron mobility is 0.018 cm²V^-1 s^-1.