Research Of Solution-processed Organic Field-effect Transistors

Organic Field-effect Transistors (OFETs) have attracted much attention due to theirpotential applications in the development of nanoelectronics and devices. They possessadvantages such as low cost, simple preparation in the film-forming process, easy processingin the low temperature, large-area and large-size manufacturing on the flexible andcompatible substrate, and etc. In the particular, OFETs based on solution-processed organicsemiconductors can be widely and potentially applied in flat-panel displays, organic lightemitting display, all the organic flexible components, identification card, large area of sensorarray, complementary logic circuit, and etc due to the achievement of the assembly oflarge-area low-cost film by printing-based manufacturing processes and spin coatingtechnology.In this thesis, the different stages of development and trend of OFETs in recent years aresimply summarizes at first. Subsequently, we further introduces solution-process development,the existing problems, the material, the preparation methods and etc. In view of the researchstatus solution-OFETs, OFETs using different dielectrics are fabricated and the influence ofdielectric on device performance are investigated. The research contents are organized asfollows:(1) P3HT-based OFETs with polyvinyl alcohol (PVA) dielectric are fabricated. Thedevices exhibit typical P-channel characteristics. The effects of PVA gate dielectricsconcentration on the performance of the devices are investigated. The experimental resultsshow the device with the concentration of8wt%displays the best performance. Furthermore,we analyzed the factor responsible for the performance improvement of the devices, whichindicates that PVA is expected to be one of insulation materials used in for the low cost, andlarge area of OFETs.(2) OFETs with different concentration of P3HT as active layer and PVA dielectric arefabricated. The results show that the performance of the device was significantly influencedby the concentration of P3HT at the constant concentration of PVA, the device with theconcentration of3mg/ml displays optimized performance. We analyze the factors of theinfluence of the different P3HT concentrations on device performanceo and find the optimalconcentration of P3HT.Based on these results, we perhaps provide the base data and a goodmethod to optimize device performance.(3) P3HT-based OFETs with both PVA and Polystyrene (PS) as the double insulator layerare fabricated. The PVA and PS, which were used as the upper and lower insulator layerrespectivley, was spin-coated on the cleaned ITO. In the device, the P3HT with theconcentration of3mg/ml in1,2-dichlorobenzeneat were used as the active layer. The10nmMoO3thin film and a120nm Al source/drain electrodes were thermally evaporated. Comparing the performance of P3HT-based OFETs with both PVA and PS gate dielectrics,and P3HT-based OFETs with PVA dielectric, the results show that the devices with doubleinsulator layer exhibits excellent P-type Characteristics, which can provide the technologicalparameters for the solution preparation of OFET.