Fabrication and Characterization of Two‐Photon Polymerized Features in Colloidal Crystals

The fabrication and characterization of two‐photon polymerized features written within and outside of colloidal crystals is presented. Two‐photon polymerization (TPP) response diagrams are introduced and developed to map the polymerization and damage thresholds for features written via modulated beam rastering. The use of tris[4‐(7‐benzothiazol‐2‐yl‐9,9‐diethylfluoren‐2‐yl)phenyl]amine (AF‐350) as an initiator for TPP is demonstrated for the first time and TPP response diagrams illustrate the polymerization window. These diagrams also demonstrate that the polymerization behavior within and outside of colloidal crystals is similar and electron microscopy reveals nearly identical resolution. Fluorescence confocal microscopy further enables visualization of non‐self‐supporting, three‐dimensional TPP features within self‐assembled photonic crystals. Finally, microspot spectroscopy is collected from a two‐photon feature written within a colloidal crystal and this is compared with simulation.     

表面贴装元件识别的一种亚像素边缘检测方法

亚像素算法是一种高精度的边缘检测算法.分析了亚像素边缘检测的原理及现有算法的优缺点,根据现有用亚像素对表面贴装元器件图像检测的算法,提出了三次样条插值的亚像素算法进行边缘提取.通过实验比较,认为该方法提高了边缘提取的精度,满足了贴片机视觉检测的要求.     

硅凹槽中硅反蛋白石光子晶体直角半波导的制备

探索了利用PECVD方法和ICP技术制备硅凹槽中硅反蛋白石(opal)结构光子晶体直角半波导的工艺条件,研究了射频功率、气体流量、反应室压力、沉积时间等PECVD工艺条件及基底状态对填充效果的影响.结果表明,降低沉积速率有利于在蛋白石结构内外均匀填充,同时在自由基扩散通道不被堵塞的前提下,增加沉积时间及蛋白石结构的规整程度,有助于反opal结构的形成.     

利用水平热壁CVD法生长的3C-SiC/Si的均匀性

利用新改进的水平低压热壁CVD设备,改变生长时的压力和H2流速,在50mm的Si(100)和(111)衬底上获得了3C-SiC外延膜,并对外延膜的结构均匀性、电学均匀性和厚度均匀性进行了分析.X射线衍射图中出现了强的3C-SiC的特征峰,其中3C-SiC的(200)和(111)峰的半高宽分别为0.41°和0.21°.3C-SiC外延膜方块电阻的均匀性最好可达2.15%.厚度均匀性可达±5.7%(σ/mean值).     

基于嵌入式硬件平台的划片机视觉系统设计

结合划片机视觉的工艺要求,设计了基于外部设备互连PCI总线嵌入式视觉系统,选用S3C2510+ARMLINUX嵌入式软硬件架构,通过S3C2510内置PCI控制器控制PCI总线接口与图像采集模块连接,获取实时图像。介绍了系统的硬件构成、Boot Loader的移植、PCI设备驱动程序的编写方法,以及获取视频数据的上层软件构成。     

用于10Gbit/s传输的对接集成DFB-LD/EA-MD光源

报道了用于10Gbit/s传输的DFB激光器和EA调制器对接集成器件的设计、制作和器件特性.工作主要集中于两个方面:提高激光器和调制器间的光学耦合;通过减小调制器电容提高调制带宽.集成器件显示出了良好的静态和高频特性:阈值电流典型值为15mA,最小值为8mA;100mA激光器偏置电流下,输出功率大于10mW;对消光比、电学回波损耗和调制带宽进行了测试,3dB带宽的测量值超过10GHz.     

Novel Conjugated Organic Dyes for Efficient Dye‐Sensitized Solar Cells

Novel conjugated organic dyes that have N,N‐dimethylaniline (DMA) moieties as the electron donor and a cyanoacetic acid (CAA) moiety as the electron acceptor were developed for use in dye‐sensitized nanocrystalline‐TiO₂ solar cells (DSSCs). We attained a maximum solar‐energy‐to‐electricity conversion efficiency (η) of 6.8 % under AM 1.5 irradiation (100 mW cm^–2) with a DSSC based on 2‐cyano‐7,7‐bis(4‐dimethylamino‐phenyl)hepta‐2,4,6‐trienoic acid (NKX‐2569): short‐circuit photocurrent density (J_sc) = 12.9 mA cm^–2, open‐circuit voltage (V_oc) = 0.71 V, and fill factor (ff) = 0.74. The high performance of the solar cells indicated that highly efficient electron injection from the excited dyes to the conduction band of TiO₂ occurred. The experimental and calculated Fourier‐transform infrared (FT‐IR) absorption spectra clearly showed that these dyes were adsorbed on the TiO₂ surface with the carboxylate coordination form. A molecular‐orbital calculation indicated that the electron distribution moved from the DMA moiety to the CAA moiety by photoexcitation of the dye.     

Amino‐Functionalized Silica Membranes for Enhanced Carbon Dioxide Permeation

Functionalization of silica membranes is important for enhancing surface interactions with specific chemicals in order to enhance separations. It is important to develop synthesis strategies that allow control over the density and the surface chemistry of the functional group in order to tailor the membrane separation properties. In this paper we investigate the ability of amino functionalization to enhance CO₂ transport in silica membranes. Specifically, we examine three synthesis techniques for functionalizing silica membranes with amino groups that result in different surface chemistries of the silica membranes. Silica membranes are amino‐functionalized by atomic layer deposition (ALD) with aminopropyldimethylethoxysilane (APDMES), ethylenediamine (EDA)‐assisted APDMES ALD, and direct attachment of aminopropyltriethoxysilane (APTES) from the liquid phase. Three different reaction schemes are presented and verified by using Fourier‐transform infrared (FTIR) spectroscopy. The FTIR measurements were performed on silica powders that were processed using the same reaction conditions as the membranes used in this study. The differences in reaction schemes are correlated with changes in the CO₂ facilitation characteristics. It is found that high loadings of amino groups, in which interaction with the silica surface is minimized, promote the highest CO₂ transport.     

Electrochromic Polymer‐Dispersed Liquid‐Crystal Film: A New Bifunctional Device

Polymer‐dispersed liquid crystals (PDLCs) are liquid‐crystal dispersions within a polymer matrix. These films can be changed from an opaque to a transparent state by applying a suitable alternating‐current electric field. PDLCs have attracted the interest of researchers for their applications as light shutters, smart windows, and active displays. For such applications, electrochromic devices, which change color as a result of electrochemical reactions, have also become a recent focus of research. Herein, we report our preliminary results on bifunctional devices based on PDLCs that host electrochromic guest molecules. Such devices allow both an independent and fast switching from a scattering opaque state to a transmissive transparent state owing to liquid‐crystal reorientation and a color change from white (pale yellow) to dark blue, due to either oxidation or reduction of the electrochromic molecules.     

A Light‐Blue Phosphorescent Dendrimer for Efficient Solution‐Processed Light‐Emitting Diodes

We describe the preparation of a dendrimer that is solution‐processible and contains 2‐ethylhexyloxy surface groups, biphenyl‐based dendrons, and a fac‐tris[2‐(2,4‐difluorophenyl)pyridyl]iridium(III ) core. The homoleptic complex is highly luminescent and the color of emission is similar to the heteroleptic iridium(III ) complex, bis[2‐(2,4‐difluorophenyl)pyridyl]picolinate iridium(III ) (FIrpic). To avoid the change in emission color that would arise from attaching a conjugated dendron to the ligand, the conjugation between the dendron and the ligand is decoupled by separating them with an ethane linkage. Bilayer devices containing a light‐emitting layer comprised of a 30 wt.‐% blend of the dendrimer in 1,3‐bis(N‐carbazolyl)benzene (mCP) and a 1,3,5‐tris(2‐N‐phenylbenzimidazolyl)benzene electron‐transport layer have external quantum and power efficiencies, respectively, of 10.4 % and 11 lm W^–1 at 100 cd m^–2 and 6.4 V. These efficiencies are higher than those reported for more complex device structures prepared via evaporation that contain FIrpic blended with mCP as the emitting layer, showing the advantage of using a dendritic structure to control processing and intermolecular interactions. The external quantum efficiency of 10.4 % corresponds to the maximum achievable efficiency based on the photoluminescence quantum yield of the emissive film and the standard out‐coupling of light from the device.