Study On Devices Of Functional Organic Materials For Application

The role of organic electronics in the electronic has become increasingly prominent since its invention,and now its development is changing everyday.The application of the functional organic materials in of all walks of life is quite extensive,expecially in the basic devices such as the field effect transistors and the field effect transistor memory devices.The deposition technology of organic materials has many advantages,such as a variety of fabrication,environment-friendly and low cost.Whether the organic semiconductor materials of a field effect transistor or the deposition methods are abundant.It provides a broader space for innovation and technology.One of the deposition methods,solution process,is of great concern because of its simple operation,low cost,environment-friendly and large-area preparation.But the deposition of the high-quality film and crystal is still a huge challenge.There are some problems such as low mobility in the organic field effect transistor and memory,which affects the operation speed of the memory and thus limits its practical application in the commercial field.This paper focuses on the application of functional organic materials and their applications in field-effect transistors and memoryies.The main works of this paper are as follows:1.We investigated the electrical switching behavior of the cross-point structure fabricated with n-type semi-organic semiconductors 2-amino-4,5-dicyanoimida-zole(AIDCN)and a self-assembled monolayer(SAM).The switching behavior of these structures is due to the charge trapping at the interface of organic/SAM layer.It is found that the electrical switching behavior is affected by the thickness of the passivation layer LiF.And the electrical characteristics are also varies with the thickness of LiF,especially the on/off ratio and the stability of the storage.The morphology of the LiF layer changes with its thickness,and then it affects the following deposition of the organic material,resulting in a different charge-trapping characteristic at the interface of organic/SAM layer.2.A novel and simple method is proposed to deposit the solution-processed organic semiconductor crystal.We used a commercial all-metal ballpoint pen as the deposition tool,of which removed the ink without any other special treatment.The pen was poured into the dioctylbenzothienobenzothiophene(C8-BTBT)solution after conventionally cleaning.And the C8-BTBT crystals were deposited on the substrate with large size(several hundred micrometers).The fabricated OFET excited excellent electrical performence,the mobility of 0.7 cm2/Vs and the on/off ratio of more than 107.In addition,the process of flow behavior was also simulated.The results show that the solution writing to the substrate from the tip of the pen produces a micro-solution flow that contributes to the formation of large-sized organic crystals.3.High-speed ferroelectric organic field-effect transistor memory was fabricated by using the two-dimensional organic material C8-BTBT and ferroelectric organic material poly-(vinylidene fluoride-trifluoroethylene)P(VDF-TrFE).The obtained delay time of from on-state to off-state and from off-state to on-state were 2 ms and 6 ms respectively.The extracted carrier mobility and on/off ratio were 5.6 cm2/Vs and 106.The addition of PMMA layer between the semiconductor layer and the ferroelectric layer optimizes the roughness of P(VDF-TrFE),resulting a high quality two-dimensional organic molecular crystal.Our fabricating strategy can speed up responses in Fe-OFET memories and demonstrates the promising application of solution-processed 2D molecule crystals in low-cost,large-area,high-performance memory devices.4.High-performance top-gate ferroelectric field effect transistor(Fe-FETs)memories using P(VDF-TrFE)and amorphous oxide semiconductor InSiO were fabricated.The extracted mobility was 84.1cm2/Vs in low-frequency state.During the annealing of P(VDF-TrFE)layer,the interfacial charge transfer between P(VDF-TrFE)and InSiO plays a key role in improving the performance of the device.The annealing temperature affected the surface morphology of the P(VDF-TrFE)and then affected the charge transfer.Higher annealing temperature bring to larger grain size of P(VDF-TrFE),much charges transfer and better electrical characteristics of the device.The work used of organic/inorganic structure,combining with the advantages of both,shows the potential of our Fe-FET memor for the next-generation electronics.As a result,we proposed some novel deposition methods to deposite large organic crystals or two-dimensional molecular crystals,and fabricated the transistors with good electrical performance.In addition,the organic ferroelectric materials can be used as a dielectric layer in the field-effect transistor memory.The switching behavior of the ferroelectric poles benefits a lot in memory performance.We fabricated high-speed field-effect transistor memories by depositing two-dimensional organic molecular crystals on organic ferroelectric materials P(VDF-TrFE).Morevoer,amorphous oxide InSiO was used to fabricate ferroelectric amorphous field effect transistor memory with hybrid structure,snd it obtained good electrical properties such as high mobility and operating speed.