Research On Preparation And Properties Of Low Emissivity AZO-based Multilayer Films

Al-doped zinc oxide（AZO）transparent conductive film is a heavily doped n-type semiconductor material with high visible light transmission（>80%）,relatively low resistivity(～10^-4Ω·cm),and excellent stability.It is worth noting the low infrared（IR）emissivity of AZO films,which shows well application prospects in the field of low-e glass.Traditional doped transparent conductive oxide（TCO）films have been studied to the limit and can’t meet the demand for high performance.To further improve the properties of the TCO films,it is prepared as laminated structures,that is,the TCO films are combined with the metal film.It has been proven that excellent optoelectronic properties can be obtained from TCO/Metal/TCO films,but there is currently less research on the infrared characteristics of multilayer films.In this research,the IR properties and photoelectric properties of AZO-based multilayer films prepared by magnetron sputtering were explored,which laid a theoretical foundation for further research and practical application of AZO-based multilayer low-emissivity films in the field of energy-saving windows.The results of the work are as follow:The effects of AZO layers on the properties of the films were systematically understood by studying the effects of different AZO layers for AZO/Cu/AZO films on photoelectricity and infrared properties.The bottom AZO layer acts as a buffer layer and has important influence on the properties of the films.The sheet resistance and IR emissivity are mainly affected by the thickness of the top AZO layer and the middle Cu layer.The transmittance of the film is affected by a combination of AZO layer at the top,AZO layer at the top and the middle Cu layer.High-performance low-emissivity AZO/Cu/AZO films with IR emissivity is 0.055,sheet resistance is 9.96Ω/sq,and average visible transmittance is 87.7%were obtained at AZO layer thickness of 40 nm.To improve the stability of the films without sacrificing the IR emissivity and electrical properties of the films.It is proposed to introduce Ti layer into the AZO/Cu/AZO tri-layer films to act as barrier to limit the oxidation of the intermediate metal Cu,thus improving the stability of the film.The introduction of Ti layers has reduced the transmittance for multilayer films,but optimized the electrical properties and IR feature of the films.When the thickness of Ti layer is 10 nm,the film has well time-stability and comprehensive properties,with IR emissivity is 0.05 and figure of merit of2.89×10^-2Ω^-1 after long exposure to air.It shows that AZO/Ti/Cu/AZO film is low-emissivity film with excellent photoelectric and IR performance and high stability.In addition,AZO/Cu/AZO films on flexible substrates are investigated in this research.Compared with AZO/Cu/AZO films deposited on glass substrates,the films deposited on flexible substrates have superior electrical properties.However,the poor thermal stability of the flexible substrate makes the IR emissivity and transmittance relatively low of the films.When the thickness of AZO layer is 30nm of the flexible AZO/Cu/AZO film,it has the best overall performance with sheet resistance is 8.73Ω/sq,average visible transmittance is 81.3%,and IR emissivity is 0.151.