【作者】 刘萍；

【导师】 任洋； 刘前立；

【作者基本信息】 西安理工大学 ， 材料与化工（专业学位）， 2023， 硕士

【摘要】 锡掺杂氧化铟(ITO)是一种重掺杂、宽禁带半导体材料,表现出较高的透明和接近于金属的导电性,常被当作透明电极应用在“ITO/阴极电致变色薄膜/离子导体/阳极电致变色薄膜/ITO”结构的电致变色玻璃器件领域。采用化学法制备ITO薄膜一般需要在400℃以上进行热处理。但是磷酸盐质子导体在高于350℃的环境中易发生相变与结晶,质子导电性能退化,难以实现“ITO/WO3/磷酸盐质子导体/NiO/ITO”的磷酸盐型电致变色器件制备。由于化学法制备WO3和NiO薄膜的热处理温度可以调整至350℃以下,因此,解决该器件制备的难点和关键点在于如何在小于350 ℃的热处理温度下获得可见光透过率大于80%和电阻率小于10-3 Ω cm的ITO薄膜?为此,本文开展了如下的研究工作:1.采用溶胶-凝胶法结合二次气氛热处理技术在玻璃基板上制备ITO薄膜,研究热处理温度(≤350℃)对薄膜的显微结构、化学组成和光电性能的影响。结果发现,当热处理温度高于290℃时,ITO为立方铁锰矿的晶体结构,并且表面形成细小的纳米晶。但薄膜内残留碳浓度较高(350℃处理的ITO薄膜C:In摩尔比为0.55:1)。不论是原子扩散还是ITO中载流子迁移,受C-H、C=O等有机残留的散射作用较强,致使Sn4+对In3+的替换和载流子迁移难以有效进行,ITO薄膜的载流子浓度仅为2×1020 cm-3,载流子迁移率为6 cm2V-1s-1,电阻率为6.45×10-3Ω cm。该性能指标难以满足电致变色器件对透明电极的要求。2.采用无碳的磁控溅射技术在玻璃基板上室温沉积薄膜,然后利用二次气氛热处理工艺获得光电性能较优的ITO镀膜玻璃。研究了溅射参数对薄膜显微结构、元素组成和光电性能的影响。研究表明,当溅射功率提高时,平均可见光透过率呈现先增大后减小的趋势,电阻率逐渐降低;随着溅射压强的提升,薄膜结晶性先增强后变差,平均可见光透过率先增大后减小,电阻率呈现先减小后增大的趋势;随着溅射时间的延长,薄膜结晶性变好,可见光平均透过率先上升后下降,电阻率逐渐降低。综合各工艺制备ITO薄膜的光电性能,得出在溅射功率为50 W,溅射压强为0.6 Pa,溅射时间为5 min的条件下,ITO薄膜的性能最优。在该条件下制备的ITO薄膜几乎没有碳残留,表面平整,无孔洞等缺陷,ITO导电玻璃的平均可见光透过率为87.79%,电阻率为6.8×10-4Ωcm,该性能ITO薄膜有望作为透明电极应用在电致变色器件领域。3.研究磁控溅射法制备的ITO薄膜在磷酸盐型电致变色器件中应用的可行性。首先采用熔融淬火结合碱质子交换技术制备磷酸盐质子导体,然后采用溶胶-凝胶法在磷酸盐质子导体两侧分别旋涂WO3薄膜和NiO薄膜,最后采用磁控溅射技术在镀膜的两侧均制备ITO薄膜,构建“ITO/WO3/磷酸盐质子导体/NiO/ITO”型电致变色玻璃器件。研究该器件的微观界面结构及电致变色性能,发现本文制备的ITO薄膜很好地实现了在磷酸盐型全固态电致变色器件中的应用。器件的着褪色对比度达到40%,着色时间为223 s,褪色时间为202 s,变色循环500次后,器件性能几乎没有衰退。更多还原

【Abstract】 Tin-doped indium oxide(ITO)is a kind of heavily doped,wide band gap semiconductor material,showing high transparency and conductivity close to metal,and is often widely used as a transparent electrode in the field of "ITO/cathode electrochromic film/ionic conductor/anode electrochromic film/ITO" structure electrochromic glass devices.ITO films prepared by chemical method generally need to be annealed above 400℃.However,the phosphate proton conductor is prone to phase transition and crystallization in an environment higher than 350℃,resulting in the degradation of proton conductivity.Therefore,it is difficult to achieve the preparation of phosphate electrochromic devices of "ITO/WO3/Phosphate Proton Conductor/NiO/ITO".Since the annealing temperature of WO3 and NiO films prepared by chemical method can be adjusted to below 350℃,the difficulty and key point to solve the device preparation lies in how to obtain ITO films with visible light transmittance greater than 80%and electrical resistivity less than 10-3 Ω cm at the annealing temperature less than 350℃?Therefore,this paper carries out the following research work:1.ITO film was prepared on glass substrate by sol-gel method,and the effects of annealing temperature(≤350 ℃)on the microstructure,chemical composition and photoelectric properties of the film were investigated.The results showed that when the annealing temperature was higher than 290℃,ITO is cubic bixbyite crystal structure,and the surface of the film shows fine nanocrystals.However,the residual carbon concentration in the film is relatively high(the molar ratio of C:In of ITO film annealed at 350℃ is 0.55:1).In both atomic diffusion and electron migration in ITO,due to strong scattering of organic residues such as C-H and C=O,it is difficult for Sn4+ to effectively replace In3+.The carrier concentration of ITO film is only 2×1020 cm-3,carrier mobility is 6 cm2V-1s-1,and the resistivity is 6.45×10-3 Ω cm.The performance index cannot meet the requirements of transparent electrode in electrochromic devices.2.ITO films were deposited on glass substrate at room temperature by carbon-free magnetron sputtering technology,and the effects of different process parameters on the microstructure,elemental composition and photoelectric properties of the films were investigated.The results show that with the increase of sputtering power,the crystallinity of the film becomes better,the average transmittance of visible light increases first and then decreases,and the resistivity decreases gradually.With the increase of sputtering pressure,the crystallinity of the film first increased and then decreased,the average transmittance of visible light first increased and then decreased,and the resistivity first decreased and then increased.With the extension of sputtering time,the crystallinity of the film becomes better,the average transmittance of visible light increases first and then decreases,and the resistivity decreases gradually.After a comprehensive comparison of the photoelectric properties,the optimal technological conditions were obtained as follows:sputtering power of 50 W,sputtering pressure of 0.6 Pa,and sputtering time of 5 min.Under such conditions,there was almost no carbon residue in the film prepared,and the surface of the film was flat without holes.The average visible light transmittance of ITO glass was 87.79%.And the resistivity is 6.8×10-4 Ω cm.ITO film is expected to be used as a transparent electrode in the field of electrochromic devices.3.The feasibility of ITO film prepared by magnetron sputtering in phosphate electrochromic devices was studied.Firstly,phosphate proton conductor was prepared by melt quenching combined with alkali proton substation technology,secondly,WO3 thin films and NiO thin films were prepared on both sides of phosphate proton conductor by sol-gel method,thirdly ITO thin films were prepared on both sides of phosphate proton conductor by magnetron sputtering technology.An "ITO/WO3/Phosphate Conductor/NiO/ITO" type electrochromic glass device was constructed,and the micro structure and electrochromic properties of the device were investigated.It is found that the ITO film prepared in this work can be well applied in phosphate all-solid electrochromic devices.The fading contrast of the device reaches 40%,the coloring time is 223 s,the fading time is 202 s,and the performance of the device does not decline after 500 coloring cycles.更多还原