Study On The Performance Of Field Effect Transistors Containing Thiophene Organic Semiconductors

Since its introduction in 1948,organic field effect transistors(FET)have been widely used in flexible devices due to their low temperature and large area fabrication,low cost and environmental friendliness,and become one of the frontiers of organic electronics research.Since organic semiconductor molecules interact through weak van der Waals forces,the charge transport mechanism of organic semiconductor molecules is completely different from that of inorganic semiconductors.Therefore,the study of organic field effect transistors has important theoretical significance.In this paper,the field effect transistor(FET)was constructed by drip method(single crystal)and spin coating method(polycrystalline film)and the carrier transmission performance was studied.Mainly carried out the following work:1.A single crystal transistor based on thienoperylene derivatives was prepared,and the influence of the dense position of thiophene on molecular accumulation and charge transport was explored.Studies have shown that these compounds all present a fishbone accumulation,and the dense position of thiophene also affects the ?-? overlapping area and contact distance between molecules.These compounds all exhibit typical P-type transport characteristics,with the highest hole mobility reaching 1.2 cm2 V-1 s-1 and an on-off ratio of 106.2.Thin film transistors based on naphthimide-based benzothiophene and benzofuran molecules were prepared,and the influence of substituents and furan on the performance of the device was explored.The results show that these compounds all exhibit typical N-type transmission characteristics,and the introduction of the electron-donating group methoxy group into the benzothiophene molecule makes the LUMO energy level of the molecule shallower,which is not conducive to electron transport and reduces the performance of the device.Different orientations of thiophene have little effect on device performance.The field effect performance of benzofuran molecules is significantly higher than that of benzothiophene molecules,and the electron mobility of the film reaches 0.28 cm2 V-1 s-1.3.Single crystal transistors based on naphthalimide-based benzothiophene molecules were prepared,and the effects of cis-trans isomerism and substituents on charge transport properties were explored.Field-effect transistor test results show that the performance of the cis-configuration molecular devices is higher than the trans-configuration,and the cumene substituent increases the steric hindrance,which affects the carrier transport and causes the performance of the device to decrease.The cis-configuration molecule of the long alkyl chain substituent obtains the largest electron mobility by the silver film method:0.26 cm2 V-1 s-1.