Organic Thin Film And Single Crystal Arrays For Organic Circuits

Organic thin film circuits have attracted extensive attention along with the quick development of organic thin film devices. As a fast and high-resolution patterning method, photolithography process will greatly facilitate the further develop ment of organic electronics. Also, it is meaningful to use polymer insulator instead of the rigid insulation layer such as metallic oxide for the fabrication of flexible electronics, simplified processes and reduced cost. Alternatively, the disadvantages existing in the fabrication process of organic single crystal greatly limit the application of the single crystal circuits. Hence, it is important and challengeable to develop a new method which could realize the fabrication of large-area, highly-ordered organic single crystal arrays efficiently. In this thesis, we are aimed to address the above issues and the main results are listed as following:Firstly, we introduced a polymer insulation-polyimide(PI), which is corrosion resistant and easy prepared. We prepared PI films under different conditions via a spin-coating method. After that, the surface morphology of the film was characterized through atomic force microscope(AFM), and other issues including film thickness, leakage current, as well as unit-area capacitance, are also measured. All of these information reflects the advantages of PI films such as the high quality- formability, good insulation and facial preparation. Furthermore, the PI film is insensitive to the solvent by comparing the permittivity, leakage current, surface morphology of the PI films before and after solvent treatment. We fabricated organic thin film transistor with the pentacene as the semiconductor layer, μ= 0.5 cm2V-1S-1, Ion/Ioff=105, which reflects a good applicability of the PI films through testing the field effect transistor.Secondly, we developed a new method which takes advantage of rapid annealing and slightly titled substrate, can realize the fabrication of large-area, highly-ordered organic single crystal arrays on the different substrates with the semiconductor 9,10-bis(phenylethynyl) anthracene(BPEA). Our method only takes a few seconds to achieve single crystal arrays. Moreover, it is very attractive that this phenomenon is independent of the substrate, and the fabrication process can be precisely tuned in an easy way. Also, the quality of the single crystal arrays was characterized by AFM, TEM, XRD, optical microscope. Transistors based on the BPEA single crystal arrays demonstrated good electrical properties and excellent photoresponse performance(Ilight/Idark =105), showing that single crystal arrays prepared by this unique method have high quality regarding the crystal inity, interface, and the electrical/photoelectric behaviors.Finally, we used the polyimide film as the insulator and photolithography was applied to fabricate organic circuits. The circuit assembling process consists of many steps such as lithography, vacuum deposition, spin-coating, annealing, oxygen plasma treatment and so on. Some simple circuits have been prepared and exhibited t he typical input/output curves. However, there is big space to optimize the fabrication process for the advanced performance and the complex circuit. O ur work might be a stimulus for accelerating the development of large scale organic circuits.