Design, Synthesis And Performance Research Of Novel Semiconductors For Organic Field Effect Transistors

Organic field-effect transistors (OFETs) have attracted much attention due to their advantages which can be fabricated at low-cost, over large areas and on flexible substrate. As one of important portion of electronic device, it can be applied in many fileds such as sensor, memorizer, display and integrated circuit etc. In this dissertation, new types of organic semiconductors materials were designed and synthesized. Their optical, electrical and thermal properties were studied by spectroscopy, electrochemical and thermoanalysis. The organic field effect transistors were fabricated based on their thin films and micro-/nano-scale crystalline and high FET performances were obtained. More details is as follows:1. A series of new organic semiconductors were synthesized in which comprising naphthalene as the central unit and benzothiophenes and/or benzofurans as the "intervening" units. UV-vis spectra and electrochemistry results showed these materials had good oxidation stability. TGA results indicated that these materials had high thermal stability. The thin films of these materials showed that the molecules were nearly perpendicular to the substrate and formed consecutive at deposited temperature at 50℃ by XRD and AFM. Mobility up to 0.13 cm2V-1s-1 and on/off ratio to nearly 106 were achieved for their thin film transistor when deposited at 50℃.2. A new kind of 2D organic semiconductor material BTBTTBT was designed and synthesized. High material stability was reavled by UV-vis spectra and electrochemistry measurements. TGA results indicated that this material had high thermal stability. The single crystal microribbons of BTBTTBT was grown by physical vapor transport method. The field-effect transistors based on the single-crystalline microribbons of BTBTTBT were fabricated. The OFET performances were measured in air and the highest mobility reached up to 17.9 cm2V-1s-1, the average mobility up to 5.57 cm2V-1s-1. And this is the highest mobility in 2D molecular.3. A new kind of 2D organic semiconductor material ATBT was designed and synthesized. UV-vis spectra and electrochemistry results showed this material had good oxidation stability. TGA results indicated that this material had high thermal stability. XRD and AFM measurement demonstrated good film-forming characteristics for this material when deposited at 80℃. Mobility up to 0.05 cm2V-1s-1 and on/off ratio to nearly 105 were achieved by testing the thin film transistor. Crystals of ATBT suitable for single-crystalline X-ray diffraction (XRD) analysis are obtained by physical vapor transport method and their crystal structures have also been determined. The field-effect transistors were fabricated based on the single crystaL of ATBT. The OFET performances were measured in air, and the highest mobility of up to 15.3 cm2V-1s-1. Our experimental results revealed that the mobility anisotropy along different crystal axes and the direction of the maximum mobility coincides with the fastest crystal-growth direction. And these results also proves the 2D molecular materials have the potential to be materials with high mobility.4. A series of new organic semiconductors were designed and synthesized in which containing dithienothiophene building block. The physical and chemical properties of these materials have been characterized. Additional studies about thin film transistors are continuing.