Research On Phthalocyanine Surface Acoustic Wave Gas Sensor

As a new type of sensor, gas sensor have received great attention due to its unique advantages such as high frequency, small size, versatility, stability and mass production of sensor devices, the unique performance of the gas sensor is successfully used in military and civilian fields including electronic counter-measure experiment, aerospace, mobile communication, radar, remote sensing, television and so on. As a novel gas sensor, Surface Acoustic Wave (SAW) sensor developed very quickly today. There are widely used in biomass, chemical content and physical testing due to their high sensitivity and low power consumption. SAW sensor technology and materials science of electronic product of the combination, which consists of SAW oscillators, the sensitive film material and the interface oscillation circuit, and to improve the sensitive films gas sensitivity is an important area of research. Metal Phthalocyanine (MPc) is a typical p-type organic semiconductor. The electron density on the distribution of very uniform, which its molecular structure is a planeπ-bond conjugated aromatic system, and a hole inside the ring, so that very few molecules in the four benzene ring deformation, therefore MPc has good chemical stability and thermal stability. The dissertation conducting in-depth study focus on the device structure, the gas-sensing properties and gas-sensing mechanism.The NO2 gas sensor films (MPc) were prepared by vacuum thermal evaporation and dip-coating. Then, the gas-sensing properties and its mechanisms are analyzed.The dissertation have two parts, the first one, the basic theory of surface acoustic wave sensor was introduced, SAW sensor modeling and model-based analysis, the choice of piezoelectric material of gas sensor, design of device structure and IDT. In which the main parameters of IDT refers to the periods, diameter, thickness of gold film, the center of input and output IDT center spacing. The second part is a research and analysis of the sensitive materials of thin films, because the laboratory detection of NO2 gas, so I chose Phthalocyanine materials as sensitive target, the films production have two kinds of coating methods that mainly by vacuum thermal evaporation and dip-coating. And then characterized the structure of thin films, discussed the test results of the gas properties of devices. Compared to the inorganic metal oxide sensitive thin films materials, organic semiconductors as gas sensing materials with high sensitivity at room temperature operation and power consumption low, good selectivity, high recovery efficiency, low working temperature, and easy to preparation. In the organic semiconductors sensitive materials, the phthalocyanines because of their good solubility, chemical stability, thermal stability, and could be replaced by changing the central ion and the group to adjust its composition and structure, but with special gas-sensitive functions. Therefore, organic phthalocyanine material is considered as one species of promising research and development of gas sensing materials.In this thesis, we mainly study metal phthalocyanine thin films as sensitive film for NO2 gas sensors.