Carbon nanotube arrays for optical design of amorphous silicon solar cells

Effective light trapping is essential for the conversion efficiency increase in thin film solar cells. Vertically aligned multiwalled carbon nanotubes (MWNTs) arrays with proper spacing form an ideal light trapping structure. In this work, we have demonstrated feasibility of the incorporation of MWNTs as back contact into amorphous silicon solar cells. Intrinsic amorphous silicon films were uniformly deposited onto vertically aligned MWNTs arrays. Scanning Electron Microscopy (SEM) was used to investigate the surface morphology of our films. The film surface area exposed to light was found to be increased dramatically due to the high-aspect ratio of MWNTs. Our findings open up a new way of managing light in thin film silicon solar cells by controlling the nano-geometry of MWNTs on substrates.     

LaNi5合金膜退火后的表面结构和氢敏特性

通过在空气中退火来改善由磁控溅射方法制备的LaNi_5合金膜的表面结构,使其具有在室温下吸放氢的能力。借助原子力显微镜、X射线衍射和X射线光电子能谱,分析了LaNi_5合金膜退火前后的形貌、结构和表层成分。结果表明:在空气中退火后,LaNi_5合金膜比表面积增加,并在其表层形成了La_2O_3-Ni的表层结构。氢敏测试结果显示,在空气中退火的样品不需要在高压纯氢中活化,在室温下即对氢气响应,说明该合金膜可以作为氢气传感器的敏感层。     

直流反应磁控溅射在3003铝箔表面制备薄膜的研究

为有效提高3003铝箔表面光泽度、比面积及强硬度,采用直流反应磁控溅射的方法.在一定溅射参数条件下,选用高纯钼靶和钛靶对3003铝箔进行溅射实验,分别在铝箔表面主要沉积出AlMo3、Al3Mo薄膜和TiAl、(Ti,Al)N薄膜,利用X射线衍射、扫描电镜分析相组成及微观组织结构,并测试了显微硬度和薄膜厚度,实验结果表明:制备出的AlMo3、Al3Mo薄膜和TiAl薄膜结晶良好,与基底结合良好,铝箔表面美观漂亮、硬度增高及比表面积得到一定提高.     

碳球模板剂对TiO2光阳极微结构及其光电性能影响研究

以葡萄糖为原料水热合成碳球作为模板剂,将其与TiO2纳米晶共混制备纳米多孔TiO2光阳极。采用场发射电子扫描电镜(SEM)、台阶仪、紫外-可见分光光度计(UV-Vis)等对TiO2薄膜的表面形貌、厚度和散射能力进行表征。研究发现,随着碳球含量的增加,光阳极单位体积内的表面积先增加后减小;薄膜对光的散射能力也呈现同样趋势。采用所制备的光阳极组装染料敏化太阳能电池,性能测试结果表明,随着碳球含量的增加,电池短路电流密度先增加,后减小。当碳球加入量为TiO2纳米晶质量的3%时,电池光电转换效率达到最佳为5.15%。     

Supercapacitors based on pillared graphene nanostructures

We describe the fabrication of highly conductive and large-area three dimensional pillared graphene nanostructure (PGN) films from assembly of vertically aligned CNT pillars on flexible copper foils for applications in electric double layer capacitors (EDLC). The PGN films synthesized via a one-step chemical vapor deposition process on flexible copper foils exhibit high conductivity with sheet resistance as low as 1.6 ohms per square and possessing high mechanical flexibility. Raman spectroscopy indicates the presence of multi walled carbon nanotubes (MWCNT) and their morphology can be controlled by the growth conditions. It was discovered that nitric acid treatment can significantly increase the specific capacitance of the devices. EDLC devices based on PGN electrodes (surface area of 565 m2/g) demonstrate enhanced performance with specific capacitance value as high as 330 F/g extracted from the current density-voltage (CV) measurements and energy density value of 45.8 Wh/kg. The hybrid graphene-CNT nanostructures are attractive for applications including supercapacitors, fuel cells and batteries.     

Highly conductive and porous activated reduced graphene oxide films for high-power supercapacitors

We present a novel method to prepare highly conductive, free-standing, and flexible porous carbon thin films by chemical activation of reduced graphene oxide paper. These flexible carbon thin films possess a very high specific surface area of 2400 m(2) g(-1) with a high in-plane electrical conductivity of 5880 S m(-1). This is the highest specific surface area for a free-standing carbon film reported to date. A two-electrode supercapacitor using these carbon films as electrodes demonstrated an excellent high-frequency response, an extremely low equivalent series resistance on the order of 0.1 ohm, and a high-power delivery of about 500 kW kg(-1). While higher frequency and power values for graphene materials have been reported, these are the highest values achieved while simultaneously maintaining excellent specific capacitances and energy densities of 120 F g(-1) and 26 W h kg(-1), respectively. In addition, these free-standing thin films provide a route to simplify the electrode-manufacturing process by eliminating conducting additives and binders. The synthetic process is also compatible with existing industrial level KOH activation processes and roll-to-roll thin-film fabrication technologies.     

竹基多孔炭上生长一维纳米炭

采用CVD法,以二甲苯为炭源,二茂铁、氯化铁等为催化剂在竹基多孔炭上生长一维纳米炭。采用扫描电镜、透射电镜及氮吸附仪等对一维纳米炭/竹基多孔炭的形貌、微结构与比表面积进行了表征。结果表明:采用CVD法可以在不同比表面积的竹基多孔炭上生长一维纳米炭(包括炭纳米管和炭纳米纤维),竹基多孔炭的比表面积越高,所获得的一维纳米炭/竹基多孔炭复合物的比表面积越大。     

Structure and Properties of Anodic Aluminum Oxide Films Produced in HNO3 Solutions

Amorphous films produced by electrochemical oxidation of aluminum in an aqueous 10 M HNO₃ solution were studied. The parameters of the nearest neighbor atomic configuration were evaluated from x-ray scattering intensities, and the surface morphology of the films was examined by scanning electron microscopy. The results demonstrate that the electrochemical dissolution of the Al substrate prevails over the oxide film growth, which results in a large specific surface area of the films.     

射频磁控溅射制备类金刚石薄膜的特性

采用射频磁控溅射技术,用高纯石墨靶在单晶硅片、抛光不锈钢片上制备了类金刚石薄膜(DLC)。采用Raman光谱、原子力显微镜、显微硬度分析仪,表征了类金刚石薄膜的微观结构、表面形貌、硬度。结果表明,制备的类金刚石薄膜中含sp2、sp3杂化碳键,具有典型的类金刚石结构特征。计算表明,对应sp3杂化碳原子含量的ID1IG为3.18;薄膜的表面十分平整光滑,表面粗糙度极低,平均粗糙度Ra为0.17 nm;薄膜硬度可以高达30.8 GPa。     

阳极氧化对PAN基高模碳纤维表面的影响

采用阳极氧化法对PAN基高模碳纤维进行在线表面处理,重点研究了氧化电流密度对炭纤维表面形貌、比表面积、表面官能团的影响.结果表明,电流密度时纤维形貌、比表面积影响不大;氧化后纤维表面官能团显著提高.根据实验结果,提出了PAN基高模炭纤维的氧化模型.     

Substrate and Fe-doping effects on the hydrophilic properties of TiO2 thin films

Titanium dioxide films are known for their hydrophilic and photocatalytic characteristics. Increasing specific surface area and doping can enhance their photocatalytic activity and hydrophilicity. We report here results regarding the enhancement of the photocatalytic properties of titania by both controlling surface morphology and the anatase/rutile ratio. The samples were deposited on glass, indium tin oxide covered glass, and SrTiO₃ by sputtering and laser ablation techniques. Film structure and surface morphology were investigated by X-ray diffraction and atomic force microscopy. Film hydrophilicity was assessed from contact angle measurements during- and post-irradiation with UV light. The contact angle data are discussed in terms of the synergic effects of surface morphology, structure and composition of the films.     

液相等离子沉积非晶态碳膜的试验研究

应用简单的电镀槽，通过阴极/电解液界面前沿气泡鞘的形成而建立辉光放电，促成非晶态碳薄膜在电极表面的沉积。沉积物宏观上分布不均匀，在阴极浸入电解液的末端，由于电流的尖端效应，导致生成物为石墨。而远离末端为正常沉积区，表面平整光滑，生成物为非。晶态碳膜。结论：液相等离子沉积行为可发生在辉光放电条件下的阴极过程，从而可应用于非晶态薄膜如非晶态碳的制备。     

异丙醇溶液中电化学法制备类金刚石薄膜的研究

采用电化学方法,以分析纯的异丙醇溶液作为碳源,低温(60～70℃)常压条件下,在(100)硅片上沉积了类金刚石薄膜。利用扫描电子显微镜(SEM)、原子力显微镜(AFM)、拉曼光谱仪(Raman)和傅里叶变换红外光谱仪(FTIR)表征了薄膜的表面形貌和结构。结果表明,电解异丙醇溶液可以获得表面均匀致密且sp3碳含量较高的含氢类金刚石薄膜。     

Vacuum-deposited carbon coatings

In recent years, highly favorable results have been obtained using low temperature isotropic pyrolytic carbons in prosthetic devices requiring a high degree of thromboresistance. The development of vacuum-deposited carbon coatings was undertaken to extend the application of carbon to geometries and configurations that cannot be fabricated from low temperature isotropic carbon. Vacuum-deposited coatings have been produced on a variety of metallic and polymeric substrates.The different vacuum deposition processes which have been investigated include electron beam gun evaporation using high vacuum, gas scattering and ion- plating conditions. In addition, sputtering processes using ion beams and magnetically confined plasmas were studied.The surface morphology, structure and preferred orientation of the coatings produced by the different processes were characterized by scanning and transmission electron microscopy. Film purity and interfacial characteristics were examined by Auger electron spectroscopy.The scanning electron microscopy study shows that thin carbon films generally have a smooth and featureless surface morphology. However, other surface morphology features are obtained in thicker films, depending on the processing conditions. The transmission electron micrographs show the absence of structure and growth features. Electron diffraction indicates that the films consist of a turbostratic phase and a non-crystalline phase. The apparent crystallite sizes are small, and there is no three-dimensional ordering. Generally, the films are isotropic and consist of relatively pure carbon, with the degree of disorder dependent on the process conditions.     

直流负偏压对类金刚石薄膜结构和性能的影响

利用直流-射频-等离子体增强化学气相沉积技术在单晶硅表面制备了类金刚石薄膜，采用原子力显微镜、Raman光谱、X射线光电子能谱、红外光谱、表面轮廓仪和纳米压痕仪考察了直流负偏压对类金刚石薄膜表面形貌、微观结构、沉积速率和硬度等性能的影响。结果表明：无直流负偏压条件下，薄膜呈现有机类聚合结构，具有较低的SP3含量和硬度；叠加上直流负偏压后，薄膜具有典型的类金刚石结构特征，SP3含量和硬度得到了显著的提高；但随着直流负偏压的升高，薄膜的沉积速率和H含量逐渐降低，而SP3含量和硬度在直流负偏压为200V时出现最大值，此后逐渐降低。     

滴涂法制备石墨烯/碳纳米管复合薄膜及其表征

以化学气相沉积(CVD)法制备的石墨烯和碳纳米管的邻二氯苯分散液为原料, 采用滴涂法制备石墨烯/碳纳米管复合薄膜, 用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、拉曼光谱(Raman)和X射线光电子能谱(XPS)对其形貌和结构进行表征。实验发现随着碳纳米管分散液浓度的增大, 复合薄膜结构中碳纳米管的面密度线性增大。利用紫外-可见光谱仪和四探针测试仪表征了不同碳纳米管浓度下复合薄膜的透光率及其薄层电阻, 结果表明: 随着碳纳米管浓度的增大, 复合薄膜的透光率及其薄层电阻都将减小, 当碳纳米管浓度为0.1 mg/mL时, 复合薄膜的透光率(550 nm)及其薄层电阻分别为92.18%和0.998 kΩ/□。实验通过调节碳纳米管浓度制备得到不同性能的石墨烯/碳纳米管复合薄膜, 该复合薄膜在透明电极、场效应晶体管和激光锁模等方面具有潜在应用。     

电绝缘用ta-C薄膜的微观结构与电学特性

采用ta—C薄膜用于SOI结构中的绝缘层，在高温高功率器件中有很大的应用潜力。应用真空磁过滤弧源沉积(FAD)的方法制备了ta—C薄膜。通过AFM、non—RBS、IR、I—V、C—V等方法对薄膜的表面形貌、微观结构和电学性能进行了研究。研究表明，ta—C薄膜的sp^3键含量高达87％，且具有很高的表面光洁度(粗糙度低于0．5nm)及较好的电绝缘性能，击穿场强达到4．7MV／cm。     

基体碳材料对锂硫电池性能影响的研究

采用乙炔黑、土状石墨、Cabot Vulcan XC-72炭黑、Cabot Bp2000超级导电炭黑作为硫载体制备了一系列含硫复合材料。通过X射线粉末晶体衍射(XRD)、扫描电子显微镜(SEM)、比表面积分析(BET)等分析测试手段对材料的物理性能进行表征,利用电池测试系统对材料的电化学性能进行了测试。结果表明基体材料表面结构、孔径分布及比表面积等因素都对复合材料的电化学性能造成影响,综合性能最好的基体材料为BP2000超级导电炭黑,其初始放电比容量高达1385.1mAh/g,在室温下经过30次循环之后电池放电比容量仍保持在1080.2mAh/g,容量保持率高达78%。     

碳纳米团簇向碳纳米纤维相转变机理研究

为了能够快速且大面积生长碳纳米纤维,研究碳纳米纤维的形成、转变及在各种物理、化学环境下的反应机理,应用等离子化学气相沉积(PECVD)方法,以CH4为反应气体,FeCl2为催化剂在玻璃衬底上生长碳纳米薄膜.应用扫描电镜(SEM)观察了碳纳米纤维薄膜的表面形貌,拉曼(Raman)光谱分析了碳纳米纤维的结构组成.结果表明,无催化剂时薄膜主要由纳米团簇构成,而催化作用下薄膜呈纤维状生长,纳米纤维为典型的碳纳米管石墨特征峰.在温度,气压,催化剂等反应条件中,FeCl2催化剂对碳纳米薄膜的取向生长起决定性作用,通过调节催化剂的浓度与分布,可有效改变碳纳米纤维的密度与分布.     

Preparation,surface properties,and MC3T3-E1 cell response of mesoporous hydroxyapatite thin films

Mesoporous hydroxyapatite (meso-HA) thin films were fabricated by a sol–gel method using cetyltrimethyl ammonium bromide as the template. The phase, surface morphology, and mesoporous structure of the meso-HA films were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The uniform thin films consisted of meso-HA spherical particles with different pore size (2.0 or 3.1 nm) were prepared on the glass substrate at different pH value (pH 3.0 or 7.0). The introduction of mesopores would enhance the surface area of HA. Water contact angle was also measured on the non-mesoporous and meso-HA thin films, revealing the promotion of surface wettability in the mesoporous ones. In vitro cytocompatibility of HA films were evaluated by cell adhesion and proliferation tests using MC3T3-E1 cells. After 3 days of culture on the samples, the cells spread in an elongated shape and were well adhered to the surface of the meso-HA films. Moreover, the cells proliferation on the meso-HA films was higher than that on the non-mesoporous films. There are significant differences in the cell density between the control group and the meso-HA films with the pores sized in 2.0 nm after being cultured for 2 and 3 days (P < 0.05). The results suggested that the presence of mesopores could influence the surface and biological properties of HA films, and the mesoporous structure would enhance the cell response of HA.