Preparation Of Low-voltage OTFTs Based On Composite Gate Dielectric Layer And Their Functional Applications

In contemporary information society,various electronic products are emerging and they have become irreplaceable in human production and life.With the development of society,there is an increasing demand for new electronic products.Organic thin-film transistors(OTFT)have the advantages of light weight and low cost,low preparation temperature,and the ability to be prepared on flexible substrates,so they have a broad application prospect in the field of large area preparation of flexible electronic devices,active driver circuits,sensors,intelligent wireless radio frequency tags(RFID),etc.Over the years,researchers have worked tirelessly to improve the overall performance of organic thin-film transistors.However,compared with traditional silicon-based inorganic transistors,organic thin-film transistors have higher operating voltages and lower mobility,which is an obstacle to commercialisation of OTFT.In this paper,we have prepared organic thin-film transistors that can operate at low voltages and improved various performance parameters of organic thin-film transistors through a series of optimisations,and studied them in terms of structural design,preparation process and interface regulation.We successfully fabricated an organic thin-film transistor that can work at low voltage,and its performance parameters have also reached expectations.The main contents and achievements are as follows:1.A series of organic thin-film transistor with 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene(C8-BTBT)as the active layer and Polyvinylpyrrolidone(PVPy)as the main gate dielectric layer were designed and prepared.Experimental data show that a single layer of PVPy as a gate dielectric layer produces hysteresis,which is a hindrance to the industrialisation of organic thin-film transistors,and the mobility and current switching ratios are not high.Therefore,the construction of a composite gate dielectric layer system is proposed to improve the mobility and device performance of organic thin-film transistors.We have designed different structures of double and triple layer polymer composite gate dielectric layers with the aim of maintaining the device to be able to operate at low voltages while having good device performance.The structurally optimised organic thin-film transistors have better performance parameters,with operating voltages below 5V,mobilities in excess of 10cm~2/Vs,average sub-threshold slopes of 185m V/decade and obtaining current switching ratios of up to 10~5.The results provide an effective theoretical and experimental basis for the further preparation of low operating voltage,high mobility organic thin-film transistors.2.Organic thin-film transistors with polyacrylic acid(PAA)as the gate dielectric layer and 2,9-dodecyl-dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene(C10-DNTT)as the active layer have been designed and tested for their photosensitive properties.In the experiments,the single layer PAA combined with C10-DNTT organic thin-film transistor can operate at low voltage and has high mobility,but it has hysteresis phenomenon and the off-state current is too high to be used as a conventional organic thin-film transistor,so the method of preparing composite gate dielectric layer was further used to improve the performance parameters of organic thin-film transistor,and we tested the photosensitive characteristics of OTFT.The experimental results shows that the threshold voltage of organic thin-film transistors under blue light is further reduced,which provides new possibilities for photosensitive organic thin-film transistors operating at low voltages.