The Preparation And Structure Of PEDOT: PSS Based Organic Spintronic Materials And Devices

PEDOT:PSS can form transparent films with high electrical conductivity on glass or plastic surface, which expands the application of PEDOT: PSS material, including in the organic solar cells, electroluminescent display, super capacitors and other electronic devices. As a polymer material, PEDOT: PSS has many advantages:the weak spin orbit interaction, long spin diffusion length, self-regulatory, smaller lattice matching, a strong electronic interaction between the lattice and thus formation of some charged a self-trapped state, which make PEDOT: PSS a good candidate for organic spintronics. In addition, it also has a simple process for large area applications, adjusted electrical properties, flexible, low weight, and so on. These features attracted more and more research interests. Therefore, it is of important theoretical and practical significance for the commercialization of new spintronic devices to research the PEDOT: PSS based organic spintronic materials and devices.Though after years of work, we gradually understand the properties of PEDOT: PSS deeply. However, there are still a lot of problems to be solved, and it is in need to accelerate the progress of invent PEDOT: PSS based organic spintronics devices. The detailed contents and main results are given below:First, PEDOT:PSS films have been spin-coated on Si substrates with different speed and time, and the surface topography, structure, optical property and their dependence on spin-coating speed and time are studied. XRD results show that the films are all amorphous. In the condition of spin-coating speed 2500 r/min and spin-coating time 30 s, the film showed good quality with the RMS roughness of 1.017 nm. The film thickness achieved by rutherford backscatter (RBS) measurement is 97.6nm. In the range of 2500 r/min-3000 r/min, the surface topography almost has no relation with the spin-coating speed. After annealing at 120℃, PEDOT: PSS films are amorphous, and the transmittance is high.Secondly, two structure of PEDOT:PSS based organic magnetoresistance devices have been prepared:ITO/PEDOT: PSS/Alq3/LiF/Al and ITO/PEDOT: PSS/Alq3/Co/Al structures. First, the properties of ITO film and Alq3 film were studied. Then the current- voltage characteristics and resistance - temperature characteristics were studied on the two structure devices. In the ITO/PEDOT: PSS/Alq3/Co/Al structure device, we obtained magnetoresistance about 1.2% at low temperature 8 K, while both ITO and Al electrodes applied 10μA current, and the results were analyzed.Finally, two structure of PEDOT: PSS-based spin valve devices: LSMO/PEDOT: PSS/Co/Al and Co/PEDOT: PSS/Co/Al sandwich structures have been prepared. First, properties of sputtering LSMO films were studied. Then, the normal giant magnetoresistance effect about 91 % was observed at low temperature 8 K on LSMO/PEDOT: PSS/Co/Al spin valve device, and we had simple explained of its origin with Mott model, In the Co/PEDOT: PSS/Co/Al sandwich structure spin valve, we can not meet the test equipment field, for the coercivity of two Co electrodes were larger, so we had not received originally envisaged magnetoresistance curve.