Resistive Switching Of TiO₂ Nanoparticle And Its Organic Composite Films By Vacuum Spray

With the developing of thin film deposition technology PVD method has been widely . used in every field, such as magnetron sputtering, electron beam evaporation and arc ion plating etc. But for new type nano-photodevice, the organic is easily to be destroied or resolved by the high temperature in the vacuum chamber. Because of this, vacuum deposition technology with low temperature is an urgent research. TiO2 is widely used by solar battery electrode material because of its higher photoelectric conversion efficiency. In this thesis, TiO2 nano-particles had been prepared by hydrothermal method, then TiO2 nano-particle and its organic composite films had been sprayed by vacuum spray and analyzed its resistive switching character.Firstly, vacuum spray experimental facility was set up by air-bleed system, temperature control system and spray system. Its base vacuum degree and working vacuum degree was 17Pa and 170Pa respectively, the highest substrate temperature was 400 ℃. Different size of TiO2 nano-particles could be prepared by different hydrothermal temperature and different hydrothermal time. It was discovered that TiO2 nano-particles was anatase at 100℃ by the detection means of FE-SEM TEM and XRD etc. With the increasing of hydrothermal time, the change on length of TiO2-nanorod was not obvious, but the diameter was larger. The crystalline of TiO2-nanorod was higher through analyzing the XRD data. After preparing the TiO2 nano-particle films by vacuum spray experimental facility, the best spraying parameter was obtained through analyzing its surface appearance and resistive switching. The detail parameter was that spraying the 5mg/ml TiO2 nano-particles 2 times under 150℃ (substrate temperature) by nozzle with 0.3mm outlet diameter. After further research of resistive switching mechanism, TiO2 nano-particle films exhibited Ohm transmission mechanism in high resistance. Contrasting with TiO2 nano-particle films by spin coating, the results show that the films prepared by two method both have resistive switching character and present the same mechanism.Secondly, organic-TiO2 nano-particle composite films were prepared by vacuum spray system. Three kinds of organics was PFBT, PVK and PMMA:Alq3=3:2. Through analyzing the morphology and resistive switching of PFBT-TiO2 nano-particle films, the best composite proportion and spraying parameter was obtained. The result shows that 1:1 composite proportion presents better resistive switching character and spraying parameter is spraying 3 times under 90 ℃ (substrate temperature) by nozzle with 0.6mm outlet diameter. After further research of resistive switching mechanism, composite films exhibited Ohm transmission mechanism in high resistance, pure PFBT films exhibited SCLC. Then basing on the result the other two organic composite films were prepared and their resistive switching mechanism were all Ohm transmission. It can be concluded that TiO2 nano-particles played leading roles in composite films. Contrasting with three kinds of composite films by spin coating, the results show that the films prepared by two method both have resistive switching character and present the same mechanism respectively. PVK-TiO2 nano-particle composite film was chose to matching by software to confirm the reliability of experimental result.