【作者】 王丽阁；

【导师】 李国卿；

【作者基本信息】 大连理工大学 ， 材料表面工程， 2008， 博士

【摘要】 非晶结构WO₃薄膜具有优良的阴极电致变色特性,是最有发展前景的电致变色材料之一;NiO_x薄膜为典型的阳极优质电致变色材料,是电致变色器件对电极层的首选材料;由WO₃薄膜和NiO_x薄膜组成的具有双电致变色膜层的互补型结构电致变色器件不仅简化了器件制作工序,而且其性能也优于传统器件,应用前景广阔。本文利用中频孪生非平衡磁控溅射技术,以纯金属为靶材,沉积WO₃、Ti-WO₃和NiO_x电致变色薄膜,优化薄膜的沉积工艺参数以提高薄膜电致变色性能,并通过多种测试手段研究薄膜的结构、成分以及电致变色性能等,得到了以下主要结果:采用中频孪生磁控溅射技术沉积的WO₃薄膜为非晶结构;XPS分析表明,薄膜表面的钨仅以+6价形式存在,而薄膜内部则由单质钨和多价态钨的氧化物组成;提高沉积气氛中的氧气含量可增大薄膜中的O/W的原子数比,薄膜的电致变色性能也逐渐提高。其中氧气流量百分比为95%条件下沉积的透明WO₃薄膜电致变色性能明显优于其他薄膜,在光波波长633 nm处薄膜着色态与透射态透光率差值可达63%。WO₃薄膜结构有利于Li⁺离子的注入和抽取,具有较好的循环稳定性和较快响应速度。不同热处理温度对WO₃薄膜影响的研究表明,经200℃热处理后WO₃薄膜仍为非晶结构,薄膜中元素的结合能没有发生变化,薄膜保持了较好变色性能,在光波波长633nm处,薄膜着色态与褪色态透光率差值接近70%;经350℃温度热处理后WO₃薄膜向多晶结构转变,晶化后薄膜的电荷容量明显减少,电致变色性能下降。原因是薄膜经热处理晶化后其结构不利于Li⁺离子的注入和抽取,使薄膜致色性能下降。对Ti掺杂WO₃薄膜的分析表明,Ti元素是以+4价形式存在。由于Ti⁴⁺和W⁶⁺的离子半径相近,因此Ti⁴⁺离子以置换W⁶⁺离子的方式掺杂于薄膜中。虽然Ti掺杂不影响WO₃薄膜中W的化合价态,膜内W元素价态与未掺杂WO₃薄膜相同,但对WO₃薄膜的结构和性能有较大影响。原因在于Ti掺杂使WO₃薄膜的表面和内部颗粒明显细化,薄膜晶化温度升高。适量Ti掺杂能有效提高WO₃薄膜响应速度和寿命、改善薄膜可逆性、减小薄膜致色驱动电压,是由于Ti的掺入抑制了WO₃颗粒结晶长大,薄膜非晶化程度提高,薄膜结构更有利于离子的注入和抽取。本实验中Ti掺杂量为5.1%的薄膜性能较好,随着Ti掺杂含量的增加,薄膜电致变色性能有所下降。制备了质地均匀NiO_x薄膜,薄膜为纳米晶结构,晶粒尺寸小于4.5 nm,薄膜表面粗糙度Ra = 1.659 nm;以Li⁺离子为致色粒子,在±3V电压作用下NiO_x薄膜对可见光调制范围可达30%以上,薄膜电致变色性能较好;纳米晶NiO_x薄膜结构易于Li⁺离子注入和抽取,电致变色响应速度快,对可见光的调节作用较大,可与WO₃薄膜组成互补型电致变色器件,对器件性能起到补充作用;制备的结构为Glass/ITO/WO₃/LiClO_4-PC/NiO_x/ITO/Glass的互补型电致变色器件,其电致变色性能明显优于结构为Glass/ITO/WO₃/LiClO₄-PC/ITO/Glass的电致变色器件,对可见光调制范围较宽,在波长633 nm处透光率差值可达81%,表现出优异的控光能力,器件响应速度快,说明互补型电致变色薄膜能显著提高器件的调控光的能力。更多还原

【Abstract】 Amorphous WO₃ film is probably the most promising one of various electrochromic materials due to its excellent electrochromic properties.NiO_x film is the preferred typical anode electrochromic material as the counter electrode layer of electrochromic device.The devices with the above two electrochromic films greatly simplify the procedure of fabrication and exhibit better performance than the traditional devices,which offer wide prospect of application.In this paper,amorphous WO₃,Ti-doped WO₃ and NiO_x films were prepared by mid-frequency dual-target magnetron sputtering using pure metal targets.With the optimization of technical parameters,the films showed good electrochromic property.The microstructure,morphology composition and electroehemical property of the films were characterized with many technologies,and the primary conclusions were listed as follow:The WO₃ films deposited by mid-frequency dual-target magnetron sputtering method at room temperature are amorphous.XPS spectra show that there is only W⁶⁺ on the film surface, and contains simple substance and mixed valence tungsten in the inner of the films.The atomic ratio of O/W increases with the oxygen content in the atmosphere,and the electrochromic performance is improved,too.In this paper,the transparent WO₃ films prepared in a sputtering atmosphere at 95%oxygen content show good electrochromism.The variation of average transmittance difference between the bleached and colored state can reach up to 63%at the wavelength 633 nm.It is because the porous structure of the films is more convenient for Li⁺ ions injection and extraction.The study on the effect of heat treatment on the WO₃ films structure at different temperatures show that heat treatment does not change the binding energy of the elements,the WO₃ films remain amorphous after annealing at 200℃and keep good electrochromism, which the variation of average transmittance difference between the bleached and colored state can reach up to 70%at the wavelength 633 nm.The films crystallize after annealing at 350℃,the charge capacity and electrochromism decrease significantly because the structure of the crystallized film makes difficult for Li⁺ ions to inject and extract.The analysis on the Ti-doped WO₃ electrochromic films shows that the valence of titanium in films is +4,without mixed valence.Ti⁴⁺ can substitute W⁶⁺ due to the similar radius with each other.Ti-doping does not affect the valence of tungsten but considerably influence the structure and electrochromic performance of the WO₃ films.For instance,the particle size is refined and crystallization temperature increase,Ti-doped can enhance the response speed and service life,improve the reversibility and reduce the value of drive voltage,as the grain growing can be restrained by Ti-doping,and the sructure is more convenient for Li⁺ ions to inject into films corresponding to the doped films than un-doped ones.In this paper,the optimum amount of doped titanium is 5.1%,and the electrochromic performance degrades with the increase of Ti-doping content.The deposited nanosized nickel oxide（NiO_x） films are of relatively clean surface that the average grain size is about 4.5 nm and the roughness（Ra） was 1.659 nm.Under±3V,the films show good electrochromic properties whose different transmittance between the bleached and colored state can reach up to 30%using Li⁺ as colouring ions in the visible region.The structure of as-deposited nanosized NiO_x films is beneficial for ions’ injection and extraction.The NiO_x films have fast response speed and good regulatory effect in visible region,which served as a supplement to WO₃ films in complementary electrochromic device. The laminated Glass/ITO/WO₃/LiClO₄-PC/NiO_x/ITO/Glass complementary electrochromic device was studied.The results indicate that the complementary device has more excellent electrochromic characters than the structure of Glass/ITO/WO₃/LiClO₄-PC/ITO/Glass device, and show good electrochromism and fast response speed with the variation of average transmittance difference between the bleached and colored state can reach up to 81%at the wavelength 633 nm.更多还原