Au纳米颗粒和CdTe量子点复合体系发光增强和猝灭效应

利用金属蒸发真空多弧离子源注入机, 将Au离子注入到高纯石英玻璃来制备镶嵌有Au 纳米颗粒的衬底材料, 随后将化学方法合成的CdTe量子点旋涂在玻璃衬底上制备了Au纳米颗粒和CdTe量子点复合体系. 通过对镶嵌有Au纳米颗粒的衬底进行热退火处理来控制Au纳米颗粒的生长和分布, 系统研究了Au纳米颗粒的局域表面等离子体共振对CdTe量子点光致发光性能的影响. 利用光学吸收谱、原子力显微镜、透射电子显微镜和光致发光谱对样品进行了表征和测试. 光致发光谱表明, Au纳米颗粒的局域表面等离子体对CdTe量子点的发光有增强效应也有猝灭效应. 深入分析了Au纳米颗粒和CdTe量子点之间的相互作用过程, 提出了关于Au-CdTe 纳米复合体系中CdTe 发光增强和猝灭的新机理. 该实验结果为利用金属纳米颗粒表面等离子体技术制备高发光性能的光电子器件提供了较好的参考.     

ZnS修饰对ZnO纳米棒：P3HT复合薄膜I-V性质的影响

本文通过化学浴沉积法获得了直径约为50 nm, 长度约为250 nm的ZnO纳米棒阵列, 引入纳米ZnS对ZnO纳米棒进行表面修饰, 分别制备得到了具有ITO (indium tin oxides)/ZnO/Poly-(3-hexylthiophene) (P3HT)/Au和ITO/ZnO@ZnS/P3HT/Au结构的多层器件. 通过I-V曲线对比讨论了两种结构器件的开启电压, 串联电阻, 反向漏电流及整流比等参数, 认为包含ZnS修饰层器件的开启电压、串联电阻、反向漏电流明显降低, 整流比显著增强, 展现出更优异的电子传输性能. 光致发光光谱分析结果证实由于ZnS使ZnO纳米 棒的表面缺陷产生的非辐射复合被明显抑制, 弱化了电场激发下的载流子陷获, 改善了器件的导电特性. 关键词： ZnO纳米棒阵列 表面修饰 电流-电压特性     

Au的金属颗粒对二硫化钼发光增强

二硫化钼(MoS₂)是一种层状的二维过渡金属硫族化合物材料,从块体到单层,禁带由间接带隙变为直接带隙,由于通常机械剥落的单层MoS₂是n型掺杂的,使得其发光效率仍然很低. 在本文中,采用匀胶机旋涂的方法将共振吸收峰在514 nm附近的纳米金颗粒尽可能均匀的铺在单层、双层以及多层的MoS₂样品表面,发现单层和双层样品的光致发光谱(PL谱)分别增强了约30倍和2倍同时伴随着峰位的蓝移,而多层样品的发光强度也略有增强. 拉曼特性揭示了纳米金颗粒对单层和双层MoS₂样品产生了明显的p型掺杂,从而增强了发光;同时纳米金颗粒的表面等离子激元效应对激发光的天线作用也是增强MoS₂的光致发光的一个因素. 关键词： 二硫化钼 光致发光 p型掺杂 Au纳米颗粒     

Al纳米颗粒表面等离激元对ZnO光致发光增强的研究

基于聚苯乙烯球自组装法,在P型氮化镓(P-GaN)衬底上制备了有序致密的掩模板;采用热蒸发法在该模板上沉积金属Al薄膜,通过甲苯溶液去除聚苯乙烯球,得到了金属Al纳米颗粒阵列;采用原子层沉积法,在Al纳米颗粒阵列表面依次沉积氧化铝(Al_2O_3)和氧化锌(ZnO).通过测试Al纳米颗粒阵列的消光谱以及ZnO薄膜的光致发光谱,研究了Al纳米颗粒表面等离激元与ZnO薄膜激子之间的耦合效应.实验结果表明:引入Al纳米颗粒后,在约380 nm位置附近的ZnO近带边发光峰积分强度增强了1.91倍.对Al纳米颗粒表面等离激元增强ZnO光致发光的机理进行探讨.     

Au/Ag纳米颗粒的成像技术与应用

基于10 nm尺度图形加工技术,通过改变金属纳米结构的大小和形貌,利用金属纳米结构的表面等离子体共振性能开发出SEM纳米彩色图片制作技术,使得图形的像素在60 nm尺度可控(约100万dpi)。利用图像处理技术可以快速生成加工版图,而通过电子束曝光和沉积技术则能够得到结构不同的Au/Ag纳米颗粒。结果表明:由于结构不同的Au/Ag纳米颗粒的表面等离子体共振性能不同,使其发光性能覆盖了可见光波段。本文通过改变Au/Ag纳米颗粒的大小,利用图像处理算法对不同大小的Au/Ag纳米颗粒进行排列组合,从而得到SEM纳米彩色图片。     

纳米ZnO和ZnO∶Eu3+的表面效应及发光特性

纳米ZnO,ZnO:Eu3+及其添加覆盖层样品的光谱性质表明,表面有机物覆盖层具有改善发射光谱,增强基质与Eu3+间能量传递的良好效果.通过比较不同温度(60,800℃)处理的ZnO:Eu3+发光强度,发现了小尺度(纳米)颗粒的特殊发光行为 关键词： ZnO 表面覆盖层 Eu掺杂     

ZnO纳米棒的低温溶液法制备、光电特性研究及其在有机/无机复合电致发光中的应用

利用水热法制备了垂直于衬底的定向生长的ZnO纳米棒,利用扫描电子显微镜及光致发光的方法对其形貌及光学特性进行了表征,利用场发射性能测试装置对ZnO纳米棒的场发射性能进行了测试.结果表明:利用水热法在较低的温度(95 ℃) 下生长了具有较好形貌和结构的ZnO纳米棒,并表现出了较好的场发射特性,当电流密度为1 μA/cm²时,开启电场是2.8 V/μm,当电场为6.4 V/μm时,电流密度可以达到0.67 mA/cm²,场增强因子为3360.稳定性测试表明,在5 h内,4.5 V/μm的电场下,其波动不超过25%.将制备的ZnO纳米棒应用到有机/无机电致发光中,其中ZnO纳米棒为电子传输层,m-MTDATA(4,4',4″-tris{N,(3-methylphenyl)-N-phenylamino}-triphenylamine) 为空穴传输层,得到了ZnO的342 nm的紫外电致发光,此发光较ZnO纳米棒光致发光的紫外发射有约40 nm的蓝移. 关键词： ZnO纳米棒 场发射 水热法 有机/无机复合电致发光     

Au:TiO2和Au:Al2O3纳米颗粒复合膜的线性和非线性光学特性

主要从实验和理论两个方面,探讨了不同Au颗粒尺寸和不同基质对Au：TiO₂和Au：Al₂O₃复合膜线性和非线性光学性质的影响.用吸收光谱研究了Au颗粒尺寸和基质与Au复合膜表面等离子体共振带之间的关系;用皮秒Z扫描技术研究了共振和非共振情况下(激发光波长分别为532nm和1064nm),Au颗粒尺寸和基质与复合膜三阶非线性极化率的关系.基于表面等离子体共振理论和局域场增强理论对复合膜进行了分析,得到了不同Au颗粒大小和不同基质时Au复合膜的 关键词： 金属纳米颗粒 复合膜 三阶非线性 表面等离子体共振     

电化学方法制备ZnO纳米颗粒掺杂类金刚石薄膜及其场发射性能研究

采用液相电化学沉积技术制备了ZnO纳米颗粒掺杂的类金刚石(DLC)薄膜, 研究了ZnO纳米颗粒掺杂对DLC薄膜场发射性能的影响. 利用X射线光电子能谱、透射电子显微镜、Raman光谱以及原子力显微镜分别对薄膜的化学组成、 微观结构和表面形貌进行了表征. 结果表明: 薄膜中的ZnO纳米颗粒具有纤锌矿结构, 其含量随着电解液中Zn源的增加而增加. ZnO纳米颗粒掺杂增强了DLC薄膜的石墨化和表面粗糙度. 场发射测试表明, ZnO纳米颗粒掺杂能提高DLC薄膜的场发射性能, 其中Zn与Zn+C的原子比为10.3%的样品在外加电场强度为20.7 V/μm时电流密度达到了1 mA/cm². 薄膜场发射性能的提高归因于ZnO掺杂引起的表面粗糙度和DLC薄膜石墨化程度的增加.     

Al/ZnO:Al薄膜结构的荧光增强效应

利用物理气相沉积设备制备了Al/ZnO:Al薄膜样品,研究了该薄膜结构的发光特性。结果表明,在ZnO:Al薄膜表面镀一层Al岛薄膜可以增强其带边荧光,同时在475 nm附近产生蓝光峰。通过在Al岛薄膜和ZnO:Al薄膜之间引入一层5 nm的Ta₂O₅绝缘层可以使ZnO:Al薄膜的带边荧光和蓝光显著增强,并随着Ta₂O₅绝缘层厚度的增大而减弱。通过对Al/ZnO:Al样品进行退火处理可以使带边荧光和蓝光峰分别增强9倍和83倍。基于局域表面等离子体共振理论,计算了Al/ZnO:Al纳米结构的光学散射和吸收截面曲线。实验结果与理论计算相一致。     

Surface–plasmon-coupled photoluminescence from CdS nanoparticles with Au films

The enhancement of surface–plasmon-coupled photoluminescence from CdS nanoparticles was examined for various thicknesses of sputtered Au films. The improved luminescence with thickness control of Au correlated well with the increased density of surface–plasmon states, which was modified by the plasmon-dispersion relation at the planar Au/PMMA interface. By annealing the Au films to form a rough surface morphology, the emission in the CdS nanoparticles was further enhanced by the improved excitation and coupling of the surface–plasmon modes.     

Porous ZnO nanobelts evolved from layered basic zinc acetate nanobelts

Novel porous ZnO nanobelts were successfully synthesized by heating layered basic zinc acetate (LBZA) nanobelts in the air. The precursor of LBZA nanobelts consisted of a lamellar structure with two interlayer distances of 1.325 and 0.99 nm were prepared using a low-temperature, solution-based method. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and infrared spectroscopy are used to characterize the as-products. PL measurements show that the porous ZnO nanobelts have strong ultraviolet emission properties at 380 nm, while no defect-related visible emission is detected. The good performance for photoluminescence emission makes the porous ZnO nanobelts promising candidates for photonic and electronic device applications.     

Synthesis and characterization of ZnO-Ag core-shell nanocomposites with uniform thin silver layers

This paper presents an investigation on the synthesis and characterization of ZnO-Ag core-shell nanocomposites. ZnO nanorods were employed as core material for Ag seeds, and subsequent nucleation and growth of reduced Ag by formaldehyde formed the ZnO-Ag core-shell nanocomposites. The ZnO-Ag nanocomposites were annealed at different temperature to improve the crystallinity and binding strength of Ag nanoparticles. The morphology, microstructure and optical properties of the ZnO-Ag core-shell nanocomposites were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, ultraviolet-visible (UV-vis) absorption and photoluminescence measurement. It was demonstrated that very small face-center-cubic Ag nanoparticles were coated on the surface of ZnO nanorods. The ultraviolet absorption and surface plasmon absorption band of ZnO-Ag core-shell nanocomposites exhibited some redshifts relative to pure ZnO nanorods and monometallic Ag nanoparticles. The coating of Ag nanocrystals onto the ZnO nanorods completely quenched the photoluminescence. These observations reflected the strong interfacial interaction between ZnO nanorods and Ag nanoparticles. The effect of Ag coating thickness on the morphology and optical properties of ZnO-Ag core-shell nanocomposites was also investigated. Moreover, the growth mechanism of ZnO-Ag core-shell nanocomposites was also proposed and discussed in detail.     

The effect of substrate surface roughness on ZnO nanostructures growth

The ZnO nanowires have been synthesized using vapor-liquid-solid (VLS) process on Au catalyst thin film deposited on different substrates including Si(1 0 0), epi-Si(1 0 0), quartz and alumina. The influence of surface roughness of different substrates and two different environments (Ar + H₂ and N₂) on formation of ZnO nanostructures was investigated. According to AFM observations, the degree of surface roughness of the different substrates is an important factor to form Au islands for growing ZnO nanostructures (nanowires and nanobelts) with different diameters and lengths. Si substrate (without epi-taxy layer) was found that is the best substrate among Si (with epi-taxy layer), alumina and quartz, for the growth of ZnO nanowires with the uniformly small diameter. Scanning electron microscopy (SEM) reveals that different nanostructures including nanobelts, nanowires and microplates have been synthesized depending on types of substrates and gas flow. Observation by transmission electron microscopy (TEM) reveals that the nanostructures are grown by VLS mechanism. The field emission properties of ZnO nanowires grown on the Si(1 0 0) substrate, in various vacuum gaps, were characterized in a UHV chamber at room temperature. Field emission (FE) characterization shows that the turn-on field and the field enhancement factor (β) decrease and increases, respectively, when the vacuum gap (d) increase from 100 to 300 μm. The turn-on emission field and the enhancement factor of ZnO nanowires are found 10 V/μm and 1183 at the vacuum gap of 300 μm.     

Chemical solution-process method to synthesize ZnO nanorods with ultra-thin pinheads and ultra-thin nanobelts

ZnO nanorods with 30 nm-diameter ultra-thin pinheads and ultra-thin nanobelts were successfully synthesized using a thiourea solution to etch nanorods and nancombs, which were obtained by a conventional thermal evaporation method. The materials obtained were investigated by field emission scanning electron microscopy and energy-dispersive X-ray fluorescence. The data shows that hydrogen ions play an important role in synthesizing ZnO nanorods with ultra-thin pinheads and ultra-thin nanobelts. Field emission plots indicated that the turn-on field was reduced from 2.10 V/μm to 1.55 V/μm after thiourea solution treatment at a current density of 0.1 μA/cm². Room-temperature photoluminescence spectra from ZnO nanostructures showed the PL spectrum peaks shifted towards short wavelengths with a large enhancement of UV bands compared with those of ZnO nanorods and nanocombs. PACS 75.55.Gs; 61.46.-w; 81.40.Wx; 78.55.-m; 78.60.Fi     

Growth and characterization of ZnO multipods on functional surfaces with different sizes and shapes of Ag particles

Three-dimensional ZnO multipods are successfully synthesized on functional substrates using the vapor transport method in a quartz tube. The functional surfaces, which include two different distributions of Ag nanoparticles and a layer of commercial Ag nanowires, are coated onto silicon substrates before the growth of ZnO nanostructures. The structures and morphologies of the ZnO/Ag heterostructures are investigated using X-ray diffraction and field emission scanning electron microscopy. The sizes and shapes of the Ag particles affect the growth rates and initial nucleations of the ZnO structures, resulting in different numbers and shapes of multipods. They also influence the orientation and growth quality of the rods. The optical properties are studied by photoluminescence, UV-vis, and Raman spectroscopy. The results indicate that the surface plasmon resonance strongly depends on the sizes and shapes of the Ag particles.     

金纳米颗粒等离激元对不同形貌氧化锌薄膜发光性能的调控

采用化学气相沉积法制备了纳米棒状的氧化锌纳米结构薄膜和没有纳米棒的氧化锌薄膜,通过直流溅射在所制备的有纳米棒和没有纳米棒的氧化锌薄膜上淀积约3 nm厚的金纳米颗粒薄膜,研究了金纳米颗粒对不同表面形貌氧化锌薄膜的发光特性的影响。实验发现金纳米颗粒的存在使具有纳米棒的氧化锌薄膜的紫外发射增强,但使来自缺陷的可见光发射受到很大的抑制。通过比较有纳米棒和没有纳米棒的氧化锌薄膜在镀金纳米颗粒前后的发光特性,发现金表面等离激元对氧化锌发光的调控取决于氧化锌的表面形貌,纳米棒的存在更有利于金纳米颗粒等离激元调控氧化锌的发光特性。     

Preparation, characterization and surface morphology of novel optically active poly(ester-amide)/functionalized ZnO bionanocomposites via ultrasonication assisted process

Novel bionanocompoites (BNCs) were prepared using zinc oxide (ZnO) nanoparticles which functionalized by γ-methacryloxypropyltrimethoxysilane (KH570) as a coupling agent. Poly(ester-amide) (PEA) based on tyrosine natural amino acid was synthesized and used as a polymer matrix. PEA/ZnO BNCs were characterized by fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). All the results confirmed that the surface of ZnO particle has sufficient compatibility with PEA through the link of the coupling agent between ZnO and polymer and also proved that the presence of ZnO nanoparticles appeared to be dispersed in nanosize in polymer composite matrix. In addition, thermogravimetric analysis (TGA) data indicated an enhancement of thermal stability of new BNC materials compared with the pure polymer.