溅射气压对WO_3薄膜电致变色器件性能的影响

Effects of Sputtering Pressure on Performance of WO_3 Thin Film Electrochromic Devices

采用磁控溅射法,以溅射气压为变量,在ITO导电玻璃上制备了WO3薄膜及TiO2薄膜,将Li+聚合物电解质涂覆于这两种薄膜之间封装成固态电致变色器件。采用XRD、AFM对WO3薄膜进行结构表征和形貌观察;采用直流稳压电源对器件进行电致变色测试,并以分光光度计测定其着色/褪色态可见光透过率。结果表明:1.5Pa溅射气压下原位沉积WO3薄膜含较多的金属W;2.0~3.0Pa溅射气压下得到了非晶态WO3薄膜;2.0Pa溅射气压下得到的WO3薄膜表面分布有狭长的颗粒团簇,表面积较大,便于着色或褪色时Li+与电子的注入或脱出,故其所封装器件的调制幅度最大,响应最快;随溅射气压的增大,WO3薄膜表面缺陷增多,器件变色性能恶化。

WO3and TiO2 thin films were prepared on ITO coated glass substrate by DC magnetron sputtering with sputtering pressure as the variable.And then Li+polymer electrolyte was coated between the two films to assemble solid state electrochromic devices.Phase composition and surface morphology of WO3 thin film were characterized by XRD and AFM.Electrochromic performance of the devices was investigated with DC regulated power supply,and their colored/bleached state transmittance of visible light was determined by spectrophotometer.The results indicate that WO3 film deposited at 1.5Pa contains W metal.Amorphous state WO3 film is achieved at the sputtering pressure of 2.0~3.0Pa.WO3 film deposited at 2.0Pa has long and narrow particle clusters distributed on the surface and relatively large surface area benefiting injection/ejection of Li+and electron during coloration/bleaching,and thus its packaged device achieves the largest modulation amplitude and the fastest response.As sputtering pressure increasing,WO3 films have more surface defects resulting in the electrochromic performance of the devices worsened.