不同溶液中浸泡处理对WO_(3)薄膜的影响

Effects of Immersion Treatment in Different Solutions on WO_(3) Thin Films

WO_(3)是一种重要的电致变色材料,可应用于屏幕显示、航天热控及智能窗等诸多领域。然而在实际应用中,WO_(3)的稳定性不足,这极大地制约了其进一步发展。利用磁控溅射法制备了非晶WO_(3)薄膜,系统研究了在去离子水、盐酸、氢氧化钠、丙酮和乙醇等不同溶液中浸泡处理对WO_(3)薄膜的表面形貌、微观结构、光学性质和电致变色特性的影响。研究结果表明,在去离子水、丙酮和乙醇中浸泡后,WO_(3)薄膜有少量溶解,表面形貌无明显变化,微观结构仍然是非晶的;在盐酸中浸泡后,WO_(3)薄膜从氧化铟锡(ITO)衬底上脱落,样品被破坏;在氢氧化钠溶液中浸泡后,WO_(3)与之反应生成晶态Na_(2)WO_(4)。在上述五种溶液中浸泡后,样品的可见光透过率都有所提升,样品的禁带宽度都变宽了。在去离子水、氢氧化钠、丙酮和乙醇溶液中浸泡后,样品的可见光透过率范围为79%~85%,其中WO_(3)的禁带宽度范围为3.22~3.40 eV,在盐酸溶液中浸泡后的样品只剩下衬底ITO,其禁带宽度为3.76 eV。在丙酮、乙醇和氢氧化钠溶液中浸泡后,样品的光学调制均显著,尤其是在乙醇中浸泡后的WO_(3)薄膜以及在氢氧化钠溶液中浸泡后得到的Na_(2)WO_(4)薄膜,它们在676.2 nm波长处的着色态与褪色态的透过率之差均为85%,显示出良好的电致变色特性。

WO_(3) is an important electrochromic material and can be used in many fields,such as the screen display,aerospace thermal control,smart windows and so on.However,in practical applications,the stability of WO_(3) is insufficient,which greatly restricts its further development.The amorphous WO_(3) thin films were prepared by the magnetron sputtering method,and the effects of soaking in different solutions such as deionized water,hydrochloric acid,sodium hydroxide,acetone and ethanol on the surface morphology,microstructure,optical properties and electrochromic characteristics of the WO_(3) thin films were systematically studied.The research results show that after soaking in deionized water,acetone and ethanol,a small amount of the WO_(3) thin films is dissolved,the surface morphology do not change obviously,and the microstructure is still amorphous;after soaking in hydrochloric acid,the WO_(3) thin film falls off from the indium tin oxide(ITO) substrate,and the sample is damaged;after soaking in sodium hydroxide solution,WO_(3) reacts with it to form crystalline Na_(2)WO_(4).After soaking in the above five kinds of solutions,the visible light transmittances of the samples are improved,and the band gaps of the samples are all widened.After soaking in deionized water,sodium hydroxide,acetone and ethanol,the visible light transmittances of the samples are in the range of 79%~85%,and the band gaps of the WO_(3) thin films are in the range of 3.22-3.40 eV.After soaking in hydrochloric acid solution,only the ITO substrate of the sample is left,and the band gap is 3.76 eV.After soaking in acetone,ethanol and sodium hydroxide solution,the optical modulations of the samples are all significant,especially the differences between the transmittances of the colored state and faded state of the WO_(3) thin film soaked in ethanol and the Na_(2)WO_(4) thin film formed by soaking in sodium hydroxide solution are both 85% at a wavelength of 676.2 nm,showing good electrochromic characteristics.