Dependence of the solar cell performance on nanocarbon/Si heterojunctions

Solar cells that combine single-crystalline silicon(Si) with graphene(G) have been widely researched in order to develop next-generation photovoltaic devices. However, the power conversion efficiency(PCE) of G/Si solar cell without chemical doping is commonly low due to the relatively high resistance of graphene. In this work, through combining graphene with carbon nanotube(CNT) networks, we fabricated three kinds of hybrid nanocarbon film/Si heterojunction solar cells in order to increase the PCE of the graphene based Si solar cell. We investigated the characteristics of different nanocarbon film/Si solar cells and found that their performance depends on the heterojunctions. Specifically, a doping-free G-CNT/Si solar cell demonstrated a high PCE of 7.9%, which is nearly equal to the combined value of two individuals(G/Si and CNT/Si). This high efficiency is attributed to the synergistic effect of graphene and CNTs, and can be further increased to 9.1% after applying a PMMA antireflection coating. This study provides a potential way to further improve the Si based heterojunction solar cells.     

基于粒子群算法的诊断策略优化技术

针对复杂武器装备系统多层次、多功能的特点以及测试性设计这一重大需求,为解决当前普遍采用的诊断策略存在的灵活性差、多故障诊断与不确定性诊断能力弱等问题,提出了一种基于自适应离散粒子群算法的诊断策略优化生成算法;该算法对自适应离散粒子群算法进行改进,引入多样性指标、个体历史最差解、扩散聚合过程和自适应惯性权重等,通过迭代计算得到最优的诊断策略;最后给出了主要步骤,并通过实例验证了算法的可行性。     

40-T混合磁体外超导磁体CICC摩擦系数测定

40-T混合磁体的建设正在中科院强磁场中心进行,其外超导磁体将由管内电缆导体CICC绕制,并采用4.5K 的超临界氦迫流冷却.CICC的摩擦系数是确定各冷却通道进口压力和流量的重要依据.文中介绍了CICC压降测量平台搭建,并对40-T混合磁体外超导磁体哑缆摩擦系数进行测量;分析了该CICC内的摩擦特性,并拟合出相应的经...     

Asymmetrical photonic spin Hall effect based on dielectric metasurfaces

The photonic spin Hall effect has attracted considerable research interest due to its potential applications in spin-controlled nanophotonic devices. However, realization of the asymmetrical photonic spin Hall effect with a single optical element is still a challenge due to the conjugation of the Pancharatnam-Berry phase, which reduces the flexibility in various applications. Here, we demonstrate an asymmetrical spin-dependent beam splitter based on a single-layer dielectric metasurface exhibiting strong and controllable optical response. The metasurface consists of an array of dielectric nanofins, where both varying rotation angles and feature sizes of the unit cells are utilized to create high-efficiency dielectric metasurfaces, which enables to break the conjugated characteristic of phase gradient. Thanks to the superiority of the phase modulation ability, when the fabricated metasurface is under normal incidence with a wavelength of 1550 nm, the left-handed circular polarization (LCP) light exhibits an anomalous refraction angle of 28.9°, while the right-handed circular polarization (RCP) light transmits directly. The method we proposed can be used for the flexible manipulation of spin photons and has potentials in high efficiency metasurfaces with versatile functionalities, especially with metasurfaces in a compact space.     

铅硼聚乙烯储源箱的屏蔽性能

由于铅对r射线的屏蔽效果非常明显，而含硼聚乙烯又是对中子漫化吸收的理想材料，所以在同时存在中子和r场的场所，从保证周围工作人员的安全出发，常用铅、硼、聚乙烯等混合材料制成屏蔽体。     

一种可视化液体传感阵列农药检测新方法

以筛选出的7种染料与合成的纳米金共同构建了液体传感器阵列,每个敏感点对不同农药样品产生不同的响应光谱,通过酶标仪采集光谱数据,结合主成分分析(PCA)、分层聚类分析(HCA)、判别分析(LDA)等模式识别方法建立了一种快速检测有机磷、氨基甲酸酯、有机氯、拟除虫菊酯类农药残留的新方法。PCA结果表明,前三个主成分反映了总信息量的92.69%,且能够对5种农药进行区分;HCA结果表明,对25个样品能够正确的归类;LDA结果表明,对5种农药识别的准确率达100%。表明这种可视化的液体阵列可为农药残留检测提供一个可靠平台,在农药残留检测中具有潜在的应用价值。     

基本加减法的口诀改革与实践

珠心算的发展已步入快车道,在教学中基本加减法(20以内加减法)是学习珠算珠心算的基础。由于各地客观条件不同,运算方法多种多样,其运算规律对7岁以下儿童来说比较复杂,难以掌握,往往存在着运     

单根准直碳纳米纤维的场发射特性

采用等离子体增强热灯丝化学气相沉积方法，以甲烷和氢气为反应气体，在钨丝衬底上制备出准直的碳纳米纤维(CNFs)，其生长密度小于10.6cm-2，长度为6—30μm，直径为60—100nm.并采用自制的双探针扫描电子显微镜系统，对所生长的单根CNF作了场发射特性研究.结果表明，其场发射开启电压约为5V/μm，相应的发射电流达到20μA/cm2，同时，对不同长度的CNFs及单根CNF不同位置的场发射研究表明，场发射电流的大小不仅与材料本身的功函数、外电场场强、材料的微观结构以及宏观的几何结构有关，而且电子在输运过程中所受到的散射也是决定场发射电流大小的关键因素. 关键词： 碳纳米纤维 化学气相沉积 场发射 扫描电子显微镜     

甲醇在热阴极DC-PCVD方法制备金刚石膜过程中的作用

采用热阴极DC－PCVD方法制备了金刚石膜，研究了甲醇对放电状态和金刚石膜生长特性的影响。结果表明，通入适量的甲醇有利于稳定辉光放电状态，保持阴性清洁，提高膜的生长质量。用扫描电镜和拉曼光谱等测试手段对金刚石膜的生长特性进行了分析。     

苄基三苯基季鏻盐的合成及其晶体结构和抗菌活性测定

合成了1种苄基三苯基季鏻盐——氯化苄基三苯基季鏻盐([BzTPP]+Cl-);利用元素分析、红外光谱、电子喷雾质谱和X射线单晶衍射对其进行了组成分析和结构表征;采用二倍稀释法测定了其抗菌活性,并与季鏻盐[BzTPP]2[CoCl4]和[BzTPP]2[MnCl4]进行了对比.结果表明,合成的季鏻盐[BzTPP]+Cl-属于正交晶系,Pbca空间群,晶胞参数为:a=1.388 0(1)nm,b=1.717 0(2)nm,c=1.817 5(2)nm,α=β=γ=90°,V=4.131 3(7)nm3,Z=8,Dc=1.191g/cm3,GOOF=1.002,R1=0.038 4,wR2=0.113 6.该季鏻盐由Cl-离子和[BzTPP]+阳离子组成,阴、阳离子之间存在C-H…Cl氢键.与此同时,三种季鏻盐对大肠杆菌、金葡萄球菌及沙门氏菌均具有较好的抗菌活性.