【作者】 傅英松；

【导师】 孙景； 杜希文；

【作者基本信息】 天津大学 ， 材料学， 2007， 博士

【摘要】 氧化锌(ZnO)为一种宽带隙氧化物半导体,是极有前途的发光材料。本文基于简单的水溶液法,制备出了分散稳定、量子产率高达76%水溶性ZnO蓝光量子点。稳定性来源于量子点表面键合的油酸分子,水溶性起源于量子点表面结合的二乙醇胺(DEA)中的羟基基团。系列对比实验证明强蓝光发射来源于激发的电子与ZnO量子点和油酸形成的ZnO/OA复合物所构成的界面态的辐射复合。采用非平衡的溶胶-凝胶路径,首次在亲脂性的PMMA基体中用醋酸锌和氢氧化锂作为原料制备出了均匀分散的ZnO纳米晶。傅立叶红外光谱(FTIR)证明在溶胶-凝胶的反应过程中,PMMA部分酯基水解生成了羧酸离子基团,而后羧酸离子基团通过化学键结合在ZnO纳米晶的表面,其完全消除了ZnO纳米晶的表面缺陷,导致ZnO纳米晶的可见光发射完全淬灭,从而发射出纯的紫外光。采用硝酸锌和DEA作为原料,在AOT-CCl4-Water所构建的反胶束模板中制备出了尺寸均一的ZnO纳米结构。研究发现通过[DEA]/[Zn2+]的比可控制ZnO纳米结构的形态和发光性能。利用透射电镜(TEM)原位观察到了反胶束对于ZnO纳米棒生长的模板作用,并证明在反胶束模板的限制作用下,量子棒的生长服从奥斯特瓦尔德熟化机制。采用低温水热合成工艺,在Zn2+-三乙醇胺(TEA)-异丙醇(IPA)体系中,通过“取向粘连”机理,生长出了各向同性的单晶ZnO微球。并揭示单晶氧化锌球的形成是一个动力学控制的过程。球形的ZnO单晶发射出强的紫外光和弱的蓝光。采用乳液聚合工艺合成了马来酸酐改性的聚苯乙烯微球(m-PS)模板,在此基础上,结合低温水热分解技术,制备了m-PS/ZnO的核壳结构。对m-PS/ZnO核壳结构的生长机理进行了深入研究。在500℃的烧结温度下,有机模板破坏,获得了单晶的ZnO杯。杯状的ZnO单晶发射出强的紫外光和弱的绿光。从实验上证明在该反胶束体系中,采用普通的氙灯作为激发源,可以实现超低阀值(抽运功率强度为～μW/cm2)随机激光发射,该随机激光阀值比普通随机激光材料低109数量级。在反胶束中引入发光的ZnO量子点,在相同的抽运强度下,随机激光发射强度可增强3倍。更多还原

【Abstract】 ZnO is a wide bandgap oxide semiconductor, which is the promising luminescent nanomaterial. Water-soluble ZnO quantum dots （QDs） with strong blue emission （quantum yield of 76%） was synthesized through a simple solution route using oleic acid （OA） as surface modifier. The stability originates from the surface-bonded OA molecules. The water-soluble of such QDs is provided by the hydroxyl groups on their surface come from diethanolamine （DEA）. Based on series control experiments, the strong blue emission is suggested to arise from the formation of surface ZnO/oleic acid complexes.Uniform ZnO nanoparticles embedded in lipophilic polymethyl methacrylate （PMMA） matrix were prepared in detail with unbalanced sol-gel route. Fourier Transform Infrared （FTIR） confirms partial ester groups of R-COOCH3 in PMMA are hydrolyzed to form carboxylic ion groups during the sol-gel reaction, which chemisorbs on the surface of ZnO nanoparticles to eliminate the surface defects, thus ZnO nanoparticles in PMMA matrix exhibits complete ultraviolet （UV） emissions, while emissions in visible region are fully quenched.ZnO nanostructures with uniform size were synthesized by confining the reaction of Zn（NO₃）₂ and DEA in reverse microemulsion system composed with CCl4-AOT-Water. It’s found that the ratio of [DEA]/[Zn²⁺] is decisive on the morphology and photoluminescence of ZnO nanostructures. The templating role of reverse micelles for producing the ZnO nanostructure is directly observed under TEM. It’s proved the growth of nanorods under the restriction of reverse micelles follows the Ostwald mechanism.The isotropic and spherical ZnO were synthesized in Zn²⁺-TEA-IPA solution with low temperature hydrothermal method based on the oriented attachment （OA） mechanism. The formation of single-crystal ZnO microsphere is a kinetic dominated growth process. ZnO quasi-spheres can emit strong ultraviolet light and weak blue light. Maleic anhydride modified PS （m-PS） templet was prepared according to emulsion polymerization process. With the m-PS as core, the m-PS/ZnO core-shell structures were synthesized by a low temperature hydrothermal route. The growth mechanism of the m-PS/ZnO core-shell is investigated intensively. Single-crystal ZnO with hollow and polyhedral structure is obtained after calcination at 500°C. Single crystal cup can emit strong ultraviolet light and weak green light.It’s experimentally demonstrated the random laser emission can be realized in reverse microemulsion system with ordinary xenon lump （the pump intensity is～μW/cm²） in AOT-CCl4-Water system. The pump threshold intensity is 109 magnitudes lower than that in common random laser. By introducing ZnO QDs in reverse micelles, the emission intensity could be 3 times than that of without ZnO QDs under the same pump intensity.更多还原