Polymer Field-effect Transistors Based On P3HT/PMMA

Polymer field-effect transistors, which have the advantages of low cost and simple fabrication, are suitable for flexible substrates and mass production. One of the challenges is the dissolution of the interface between a polymer semiconductor and a polymer insulator when the polymer semiconductor is spin-coated on the polymer insulating layer, leading to a decrease in device performance. In this thesis, we prepared polymer field-effect transistors based on3-hexylthiophene (P3HT) and polymerthyl methacrylate (PMMA) and optimized the preparing conditions for the PMMA insulating layer and the P3HT semiconducting layer to improve the device performance.First, we optimize the PMMA thickness with PMMA solutions in ethyl acetate of different concentrations and find out that the suitable thickness of PMMA is400nm. Then we utilize a mixture of chloroform and cyclohexane with the volume ratio of3:7as a solvent of P3HT to decrease the dissolution effect of the PMMA layer when spin-coating the P3HTlayer. The SEM image shows that the films of P3HT and PMMA are fabricated with a very clear interface.In order to improve the device performance of P3HT/PMMA field-effect transistors, we investigate the influences of annealing method, annealing temperature, and metal electrodes. It is found that the device annealed at80℃before evaporation of the Au/Al electrodes shows the best performance. It has a carrier mobility of5.6×10-6cm2/V·s～5.51×10-5cm2/V·s.