Study Of Solution Processed Organic Thin-Film Transistor

Organic field-effect transistors(OFETs) have been attracted interest by areas of chemistry, physics, materials, and microelectronics in these two decades. Because OFETs are considered as a key component of organic integrated circuits for use in ?exible smart cards, low cost radio frequency identi?cation(RFID) tags, and organic active matrix displays. In order to obtain OFETs with high performance, a large amount of effort has been devoted to the synthesis of novel semiconductors and the development of new fabrication techniques.Deposition of organic small-molecules from solution is a versatile low cost route for the fabrication of organic electronic devices. Due to the improvement of solubility of the small-molecule derivatives and the ordered structure and high mobility that they’ve shown, solution-processed organic field effect transistors has become the hot spot in recent years.The development, applications and current situation of OFETs research has been addressed in this paper. And then overviewed the basic structure of OFETs devices, common semiconductor, dielectric and electrode materials for OFETs. And also introduced the work function of the device and the carrier transport mechanism for OFETs. Finally, we focused on small molecules materials and OFET. On the basis of choosing organic semiconductor, we deposit TIPS-Pentacene and C8-BTBT organic thin films and fabricate the OFETs device based on the two kinds of materials.The main research work and conclusions include:(1) Via a simple and novel solution processed method—hollow capillary writing, we deposited TIPS-Pentacene and C8-BTBT organic thin-films respectively on Si/SiO2 substrates. And we further explored depositing TIPS-pentacene film on silicone flexible substrates. Finally we studied the effect of writing speed on the film morphology and also the structure of film through X-ray scattering. We found that highly uniform and continuous film are made by the method. Grain size is affected by the concentration of solution and speed of substrate and can be up to 1mm wide and more than 10 mm long along with the writing direction.(2) We fabricate OFETs device with SiO2 dielectric layer, high-mobility TIPS-Petacene and C8-BTBT as active layer and vacuum-evaporated gold as source and drain electrodes. The device showed typical p-type transport property. We studied the optimal parameter for gold deposition by measuring the gold thickness via four probe approach. We also studied the effect of writing speed, film morphology and direction of the channel on the film performance. The mobility for TIPS-Pentacene based OFET and C8-BTBT based OFET is 0.87 cm2/V·s and 2.79 cm2/V·s respectively.