Printed Electronics Technology And Its Application On Organic Electronic Devices

The conventional electronics technology, such as lithography process, usually wastes lots of material, costs too much and pollutes the environment. Moreover, the process is too complicated to be carried in Roll to Roll production. On the other hand, printing process is relatively simple and inexpensive, therefore, attracts plenty of attention of researchers and companies all over the world. In this thesis, the specific printing process is discussed and its applications on organic electronic devices are investigated. The first chapter is overview of printed electronics. In chapter2, we describe the printing parameters, ink information and film forming process in ink-jet printing. In chapter3, transparent silver mesh is investigated. The transparency and sheet resistance are predicable based on a theoretical model. The methods of fabrication of the transparent silver electrodes are summarized. The advantages and disadvantages of these technologies are analyzed. The transparent silver mesh electrodes are prepared by micro-gravue printing and its transparency (75%) and sheet resistance (9.0Ω/□) were measured. The silver electrodes could be the next generation of transparent electrode applied in devices such as OLED, touch screen, solar cell etc. In chapter4, a poly (vinylidene fluoride-trifluoroethylene) ferroelectric copolymer random access memory device on PET substrate with both ink-jet printed top and bottom electrodes is proposed. The device exhibits a remanent polarization of8.03μC/cm2, which shows approximately the same level with that of device based on vacuum evaporated Ti electrode. However, the device with Ag electrodes requires thicker P(VDF-TrFE) film to prevent short circuits since silver possesses high mobility. Therefore a higher driving voltage (23V) and higher coercive voltage (10.28V) are observed than those of device with evaporated Ti electrode (Vd=9V, Vo=3.58V). It has been proven that an electroactive layer could prevent the Ag solution from permeating into the P(VDF-TrFE) polymer layer, which makes it possible to lower down the P(VDF-TrFE) film thickness. It is possible to achieve a ferroelectric device with lower driving voltage and coercive voltage. In chapter5, we discuss the possible applications on other electronic devices of printed electronics technology.