Research On Gas/Humidity Sensors Based On All-Inorganic Halide Perovskites

With the development of society,gas humidity sensor plays an increasingly important role in the fields of industry,agriculture,smart home and environmental monitoring.All-inorganic halide perovskite materials have attracted much attention in the field of gas humidity sensing due to their excellent carrier transport properties,good surface sensitivity and chemical stability.Therefore,this thesis explores the gas/humidity sensing properties of typical halide perovskite CsPbX₃(x=Cl,Br,I)and new halide perovskite CsCu₂I₃ sensors,which lays a foundation for the further development of all-inorganic halide perovskite sensors in the future.It mainly includes the following contents:(1)Synthesis of low dimensional CsPbX₃ sensitive materials with different halogen anions.CsPbCl₃ with flake structure,CsPbBr₃ with spherical structure and CsPbI₃ with rod structure are successfully synthesized by solution coprecipitation method.(2)Research on the performance of gas/humidity sensor based on CsPbX₃.Firstly,by monitoring the impedance of the sensor in real time,it is found that the sensitivity of CsPbX₃ humidity sensor to humidity increases with the increase of atomic radius of halogen elements.Then,by analyzing the long-term relative humidity stability of the sensor,the stable impedance conversion performance of lead halide perovskite is obtained.Finally,it is found that CsPbX₃ is not sensitive to gas.(3)One dimensional network structure of lead-free CsCu₂I₃ sensitive material is synthesized.The self-organized radial CsCu₂I₃ one-dimensional needle like clusters are prepared by ligand assisted reprecipitation method.(4)Research on the performance of gas/humidity sensor based on CsCu₂I₃.Firstly,by monitoring the resistance change of the sensor in real time,it is found that the sensor has the potential of monitoring trace NO₂gas and recognizing respiratory biomarkers,that is,the detection limit of ultra-low concentration(ppb level),rapid response and recovery,and good selectivity.Then,the sensing mechanism of CsCu₂I₃ nanostructure network is explored,which is related to its unique needle like cluster network structure and a large number of cation vacancies on the surface of perovskite.Finally,it is found that CsCu₂I₃ has good moisture resistance.The experimental results show that:with the increase of atomic radius of halide elements(Cl,Br,I),the humidity sensor based on CsPbX₃ is more and more sensitive to humidity,but not sensitive to gas.The environmental friendly lead-free halide perovskite based on CsCu₂I₃ has good sensitivity to NO₂ and is insensitive to environmental humidity,so it is suitable for gas sensor.It can be seen that all-inorganic halide perovskite materials have unlimited possibilities in the field of gas humidity sensing.