摘要
光谱选择性透过涂层在节能窗上能有效反射红外光,通过减少室内外的热传递而降低能耗。本文分别测量SiN膜和Ag膜的透射光谱和光学常数,利用TFCale软件对SiN/Ag/SiN选择性透过涂层的各层厚度进行优化设计并利用磁控溅射进行制备。使用紫外-可见-近红外分光光度计(UV/VIS/NIR)、扫描电子显微镜(SEM)和俄歇电子能谱(AES)测试与表征涂层的选择透过特性、微观形貌与成分分布。结果表明,实际制备的涂层厚度及光学性能与理论设计值具有良好的一致性。当SiN/Ag/SiN涂层的各层厚度分别为30/15/35 nm时,其可见光和近红外波段的透射率分别为73.1%和17.2%,体现出明显的选择透过性。观察Ag膜的生长模式,发现15 nm的Ag膜仍处于岛状粒子生长阶段,上层的SiN层粒子会在沉积过程中进入Ag岛之间的缝隙。探究不同类型涂层的光学性能,发现金属Ag薄膜对选择透过涂层的红外透过率有显著影响,且外层的SiN薄膜是保证涂层可见光透过率的关键因素。
Energy conservation was one of the most effective ways to solve energy shortage problem.Energy-efficient window was considered to be the first step for reducing energy consumption in the field of smart buildings,which managed solar energy in glazing elements,like filters that let pass some energy wavelengths through and rejected others.Solar selective transmittal coating could effectively reflect the infrared light on energy-saving window,and decrease energy consumption by reducing indoor and outdoor heat transfer.There were mainly three types of transparent heat reflecting materials:(1)a single layer of thin metal film such as Ag,Cu,Al;(2)a heavily doped semiconductor with wide band-gap such as indium tin oxide(ITO)and fluorine doped tin oxide(FTO);(3)a dielectric/metal/dielectric(DMD)structure such as ZnS/M/ZnS,ZnO/M/ZnO and ITO/M/ITO.Compared to semi-conductor,the DMD structure had excellent characteristics of low radiation and easy regulation,but its large-scale deployment was subject to stability,durability,design and cost of materials.Ag film was the most preferred choice as the metal layer,owing to its lower VIS absorptance,excellent electronic and optical properties.Thin film SiN was widely used for antireflection and surface passivation layer to enhance the performance of solar cells because of its high optical band gap and refractive index.In this study,the transmittances and optical constants of SiN film and Ag film were measured,respectively.For the design of the SiN/Ag/SiN coating,different models could be used to fit the optical constants of each layer.On the one hand,B-splinemodel was used to fit the refractive index and extinction coefficient of Ag film.In the range of 380~1600 nm,the refractive index of Ag film increased from 0.07 to 0.3,while the extinction coefficient increased from 1.7 to 11.2.On the other hand,the refractive index and extinction coefficient of SiN film were fitted by Codylor model.The refractive index tended to be 1.7~1.8,and the extinction coefficient tended to be 0 in the range of>400 nm.The thickness of each layer of SiN/Ag/SiN selective transmittal coating was optimized by TFCale,and the coating was prepared by magnetron sputtering.UV/VIS/NIR spectrophotometer,scanning electron microscope(SEM)and auger electron spectroscopy(AES)were used to characterize the spectral selectivity,micro-morphology and profile chemical composition.The results showed that the actual thickness and optical properties of the coating were consistent with the theoretical designs.The transmittance of the coating increased rapidly in the visible range,and then decreased in the near-infrared range,reflecting obvious selective transmission characteristics.When the thickness of each layer of SiN/Ag/SiN coating was 30/15/35 nm,the transmittance was 73.1%in visible region and 17.2%in near infrared region respectively,achieving good spectral selectivity.By observing the growth mode of Ag film,it could be found that the Ag film of 15 nm was still in the stage of island-like particle growth,so the particles of upper SiN layer could be deposited between Ag islands.By exploring the optical properties of different types of coatings,it was found that Ag film had a significant effect on the transmittance in near infrared region,while the upper SiN was a key factor to maintain the transmittance in visible region.
作者
许科
杜淼
郝雷
米菁
于庆河
李帅
Xu Ke;Du Miao;Hao Lei;Mi Jing;Yu Qinghe;Li Shuai(National Engineering Research Center of Nonferrous Metals Materials and Products for New Energy,GRINM Group Co.,Ltd.,Beijing 100088,China;GRIMAT Engineering Institute Co.,Ltd.,Beijing 101407,China;General Research Institute for Nonferrous Metals,Beijing 100088,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2022年第8期1055-1062,共8页
Chinese Journal of Rare Metals
基金
国家自然科学基金项目(51801178)资助。
关键词
光谱选择透过涂层
光学常数
优化设计
透射率
solar selective transmittal coating
optical constants
optimization design
transmittance
