Research On Inkjet-printed Organic Field-effect Transistor And Its Performance

Organic semiconductor technology has attracted a lot of attention because of its characteristics of large area, low end, lightweight and flexible electronic applications. Organic field-effect transistors(OFETs) have more and more business opportunities. The ink-jet printing because of its non-contact processing, pattern adjustment flexibility and low cost is more and more popular. This thesis mainly focuses on improving the performance of organic field-effect transistor and preparation of inkjet printing organic field-effect transistors. The specific contents are as follows:First of all, this thesis used inkjet Dimatix-300 to prepare electrode of silver nanoparticles and poly-hexylthiophene(P3HT) organic semiconductor layer. The point, line and surface of the Ag electrode were prepared by changing the different drop spacing. Poly-hexylthiophene(P3HT) films were prepared on the Si O2 surface by changing the drop spacing. And then study the film formation. Secondly, We found that the coffee ring effect appeared in ink-jet printing preparation of silver electrode, in order to improve the situation, we study from three imfactors including the substrate temperature, printing layers and drop spacing. The results show that the substrate temperature set 35℃, printing 3 layers and drop spacing set 60 μm can greatly reduce the coffee ring of silver electrode.Thirdly, in order to improve the performance of OFETs, we study two methods of surface modification including self-assembly film(SAMs) and polymer modification. We choose Octadecyltrichlorosilane(OTS-18) and polystyrene(PS) as gate insulating layer. The results show that the surface roughness of organic semiconductor thin film is reduced, which is more favorable for the transmission of the charge, thus improving the performance of the device. Fourthly, we use the mask evaporation combining with ink-jet printing method to prepare OFET. We study the effect on device performance by printing different layers of the organic semiconductor. The results show that when printing one layer of P3 HT organic semiconductor, coffee ring effect is reduced and the morphology of the film in the channel of the device is improved. Finally, we study the OFET experiments of inkjet printing electrodes and organic semiconductor layers. The results show that the performance of the OFET device prepared by inkjet printing is slightly less than that of the device prepared by evaporation, but the difference is not great, which provides reference for the subsequent use of inkjet printing.