Synthesis Of Organic Semiconductor Hexadecachlor Zinc Phthalocyanine And Its Chlorine Gas Sensor

With the development of petrochemistry industry, gases appear in different forms such as combustible, explosive, toxic and harmful, and their application can be increasingly found in many areas. When leaking, these gases will cause poisoning, fire or even explosion, which greatly endangers human lives and safety of property. Therefore, much importance should be attached to the effective measures to be taken, the accidental gas leakages to be avoided, and the content of some certain gases to be detected in time and without fail. To realize these, the requirement for gas sensors, the core unit of the gas detection device, becomes severely high, but the arrival of the new materials makes it possible for the development of gas sensors, especially the novel gas sensing materials.The latest progress and research have been focused on the macromolecular functional materials used in gas sensors. So far, a universal study on the gas sensing materials has been made in phthalocyanine(Pc), polyaniline, porphyrin, and their derivatives & complexes, among which Pc was considered as the promising one for the gas sensing materials, because of its high chemical and thermal stability, and also can be of preferable sensitivity and selectivity by modification like the adjustment of central metal and the substituents of peripheral or axial atoms.The method of ammonium molybdate solid phase catalysis was introduced in this experiment, and by using tetrachlorophthalic anhydride and urea as the raw materials, hexadecachloro zinc phthalocyanine(ZnPcCl16) was synthesized. The composites were analyzed and characterized by energy spectrum, X-ray diffraction, IR and UV-vis spectroscopy. The films of gas sensors were prepared in a vacuum evaporation system and evaporated onto Al2O3 substrates, where interdigital electrodes with heating units on the back were made by MEMS micromachining. The influencing parameters of vacuum evaporation plating on the sensitivity of the films were analysed, and the test was carried out on chlorine (Cl₂) gas. Finally, the gas sensing mechanism was explained by establishing the physicochemical adsorption model of organic semiconductor.The optimal conditions for the films are: substrate temperature of 150℃, evaporation current of 95 A and film thickness of 50 nm. The result showed that the sensors were ideally sensitive to Cl₂ gas and very stable in the high concentration Cl₂ gas atmosphere, and could detect the minimum concentration of 0.3 ppm.