TiO2-SiO2/SiO2双层复合薄膜制备及折射率调控

Refractive Index of Double-layer TiO2-SiO2/SiO2 Composite Thin Films Prepared via Sol–Gel Method

采用溶胶-凝胶法制备了具有W型减反特性的Ti O2-SiO2/SiO2复合薄膜,并分别调控了TiO2及TiO2-SiO2混合介质薄膜折射率,探索了不同制备条件对TiO2薄膜折射率的影响机理。通过场发射扫描电子显微镜、能谱仪、椭偏仪、紫外–可见-红外分光光度计研究了薄膜微观结构、薄膜组分、折射率和光学透过率,通过TFcal软件模拟了双层复合薄膜的光学透过率线型。研究表明:溶胶pH值对TiO2薄膜折射率影响显著,其影响的前驱体水解速率对折射率的影响占主要作用,并且随着pH值的增大薄膜折射率减小,而水/钛比对薄膜折射率影响不显著。在TiO2与Si O2混合溶胶中两者物质的量比为1.2:1.0时,获得可用于制备双层复合W型减反膜系底层的薄膜,其椭偏仪拟合测试折射率约为1.68。最终制备的复合TiO2-SiO2/SiO2薄膜实现了光学宽谱范围380~1100 nm的优良增透效果,最大透过率可达约97%。

Double-layer TiO2-SiO2/SiO2 composite anti-reflective thin films with W transmittance line type were prepared by a sol–gel method,and the refractive index of TiO2 and composite TiO2–SiO2 thin films was regulated.The preparation condition on the TiO2 thin film refractive index was investigated.The phase,film components,refractive index and transmittance of the films were characterized by field emission scanning electron microscopy,energy disperse spectroscopy,ellipsometry and ultraviolet–visible–infrared spectrophotometry,respectively.The transmittance line type of double-layer composite films was simulated by a software named TFcal.The results show that the pH value of sol system is more crucial to the refractive index of TiO2 thin films,and the refractive index decreases when the pH value increases,compared to the ratio of H2 O/Ti.Meanwhile,the pH value derived hydrolysis rate has an effect on the refractive index of the final film.The composite TiO2-SiO2 films used as the bottom layer of the films system are obtained when the mixture mole ratio of Ti/Si is 1.2:1.0 and the refractive index is 1.68.The double-layer TiO2-SiO2/SiO2 composite thin films obtained have an antireflection effect in the wide optical wavelength range of 380–1100 nm,and the maximum transmittance can reach to 97%.