基于裂结技术的单分子尺度化学反应研究进展

分子电子学是研究单分子器件的构筑、性质以及功能调控的一门新兴学科。其中,金属/分子/金属结的构筑和表征是现阶段分子电子学的主要研究内容。裂结技术是当前分子电子学研究的主要实验方法,主要包括机械可控裂结技术和扫描隧道显微镜裂结技术。本文对裂结技术进行了介绍,并对近年来利用这些技术,在单分子尺度化学反应的检测和动力学研究,以及将这些技术与溶液环境、静电场、电化学门控等方法相结合,调控单分子器件的电输运性质等方面所取得的进展进行了概述。     

吡啶基客体分子对枝状分子表面线状模板的选择性调节

利用扫描隧道显微术(STM)研究了枝状分子BIC3与4,4′-联吡啶(BP),吡啶乙炔撑衍生物(PE3,PE4)等分子在石墨表面的二元共组装结构.BIC3分子能够在端基为吡啶基的客体分子诱导下,形成柔性线状分子模板,并捕捉客体分子形成线状主客体结构.通过选择客体分子结构,可选择性调节BIC3主体模板结构及最终的主客体二元结构.例如,客体分子吡啶端基的间距决定BIC3-吡啶基分子主客体结构中的氢键作用方式,而客体分子侧向宽度及吡啶环的数目影响线状主客体结构的条垄间距和分子比例.研究结果为可控构筑线状主客体纳米结构,实现表面自组装结构的功能性提供了思路.     

有机分子电致发光材料进展*

由于有机电致发光器件在彩色平板显示等领域具有极大的应用前景,已引起广泛的关注。与无机物相比,有机发光材料具有高荧光效率、颜色的广泛选择性及易成膜性。本文主要介绍近年来有机分子电致发光材料最新的发展,并特别讨论了齐聚物和含载流子传输单元的发光体。     

碳基纳米电极在分子器件中的应用

在器件微小化的发展趋势下,以单个或少数几个分子为主体的分子器件开辟了一条将“自下而上”的化学合成、组装与“自上而下”的微纳加工技术有机结合的研究新思路。如何有效构筑新型的功能化分子器件,使之有利于实现与硅基电子器件的互补集成,是该领域发展亟需解决的关键问题,这就需要相应地发展新的材料和方法来构筑器件。碳纳米管和石墨烯这2种新型碳家族纳米材料,由于其独具魅力的结构和性质自被发现以来便在全世界范围内掀起了研究热潮,可以作为一种良好的电极材料应用于分子器件的构筑和发展。主要简述了分子器件的发展概况,特别是碳纳米管和石墨烯作为电极材料在分子器件中的应用基础研究。     

磁性分子自旋态检测与调控的STM研究

单分子自旋态检测与可逆调控是目前物理、化学及信息技术等领域的研究热点．本文综述了扫描隧道显微镜在该领域的研究进展,着重论述了酞菁类磁性分子在金属单晶表面或绝缘层薄膜上磁性的检测;自旋交叉配合物分子自旋双稳态的检测与可逆调控;单分子磁体的表面制备及输运性质的检测．     

共轭聚合物材料及电致发光器件

共轭聚合物是一种极有应用前景的有机半导体材料,本文综述其研究进展,包括典型共轭聚合物材料PPV、PT、PF等及PPP的工作原理,发展前景和存在的问题。     

分子模拟在有机聚合物电致发光材料设计中的应用

对聚合物分子模拟理论和一种较为精确的聚合物模拟方法－地简要的介绍，分析模拟计算的结果如能量结构、前线轨道能级、能带结构、跃迁能等与电致发光相关的测定指标如导电性、氧化还原电位、光电子能谱、吸收与发光谱、光氧化性、热稳定性相关联。并讨论了分子模拟辅助电致发光新材料设计上的应用。     

热活化延迟荧光聚合物及其电致发光器件

热活化延迟荧光(TADF)聚合物,不仅具有小分子TADF材料高的激子利用效率特性,而且还具备分子多样性好、可溶液加工、低成本、以及易实现大面积柔性器件等诸多优势,在近几年受到广泛的关注并展现了良好的应用前景。本文从TADF聚合物分子设计原理、器件结构及发光机理出发,依据TADF聚合物的构筑方法不同,概括了其结构设计策略,详述了各种类型TADF聚合物的分子结构和光电性能及其在有机电致发光器件领域应用的研究进展,最后探讨了TADF聚合物存在的问题,并展望了其发展前景。     

自组装单分子膜功能器件

分子尺度电子学是利用单个分子或分子单层组装体作为活性单元来实现电子学功能的一门前沿科学领域.基于自组装单分子膜(SAMs)的分子器件在分子电子学的实用化道路上具有很大的发展潜力与应用前景.目前,SAMs功能器件的研究仍处于起步阶段,其性能还有很大提升空间.本文首先评述了SAMs器件的构筑方法,针对直接蒸镀金属顶电极会对SAMs造成破坏的问题,介绍了3类软接触电极,包括液态金属、导电高分子和石墨烯顶电极;然后以固态光开关器件为例介绍了近年来功能器件上的一些新进展,分子优化设计对于提升器件响应活性具有重要意义;同时总结了共轭聚合物SAMs器件的制备方法和性能,通过合理的结构设计,共轭聚合物能进行电荷的长程输运,并有望提供比小分子更优异的光电功能;最后讨论和展望了未来的发展方向.     

白光有机电致发光器件进展

白光有机电致发光器件（WOLEDs）在显示和照明领域有着极大的应用前景,受到人们广泛的关注。本文从多个方面综述了WOLEDs近年来的研究进展,探讨了它的应用前景及需要解决的问题。     

Molecular and nanoscale materials and devices in electronics

Over the past several years, there have been many significant advances toward the realization of electronic computers integrated on the molecular scale and a much greater understanding of the types of materials that will be useful in molecular devices and their properties. It was demonstrated that individual molecules could serve as incomprehensibly tiny switch and wire one million times smaller than those on conventional silicon microchip. This has resulted very recently in the assembly and demonstration of tiny computer logic circuits built from such molecular scale devices. The purpose of this review is to provide a general introduction to molecular and nanoscale materials and devices in electronics.     

电极距离对4,4’-联苯二硫酚分子器件非弹性电子隧穿谱的影响

基于杂化密度泛函理论和格林函数方法, 计算了4,4’-联苯二硫酚分子器件的非弹性电子隧穿谱, 并研究了电极距离对该非弹性电子隧穿谱的影响. 计算结果表明, 非弹性电子隧穿谱随电极距离的改变呈明显不同的特征, 从而表明了分子的非弹性电子隧穿谱技术能够灵敏地反映出分子器件的微观结构. 研究结果显示, 垂直于电极表面的振动模式对非弹性电子隧穿谱具有较大的贡献.     

Imaging Molecular Orbitals of Single Picene Molecules Adsorbed on Cu(111) Surface: a Combined Experimental and Theoretical Study

Picene, which attracts the great interest of researchers, not only can be used to fabricate thin film transistors with high hole mobilities, but also is the parent material of a new type organic superconductor. Here, we investigate the electronic properties of individual picene molecules directly adsorbed on Cu(111) surface by a combination of experimental scanning tunneling microscopy/spectroscopy measurements and theoretical calculations based on the density functional theory. At low coverage, the picene molecules exhibit mono-dispersed adsorption behavior with the benzene ring planes parallel to the surface. The highest occupied state around-1.2 V and the lowest unoccupied state around 1.6 V with an obvious energy gap of the singly adsorbed picene molecule are identified by the dI/dV spectra and maps. In addition, we observe the strong dependence of the dI/dV signal of the unoccupied states on the intramolecular positions. Our first-principles calculations reproduce the above experimental results and interpret them as a specific molecule-substrate interaction and energy/spatial distributions of hybrid states mainly derived from different molecular orbitals of picene with some intermixing between them. This work provides direct information on the local electronic structure of individual picene on a metallic substrate and will facilitate the understanding the dependence of electron transport properties on the coupling between molecules and metal electrodes in single-molecule devices.     

Molecular-scale electronics: From device fabrication to functionality

Device fabrication and functionality are two crucial aspects in molecular-scale electronics. Recent advancesin this field, including fabrication and application of nanogap electrodes, self-assembled monolayers and their functional devicesarehighlighted in this review paper.     

Properties of large organic molecules on metal surfaces

The adsorption of large organic molecules on surfaces has recently been the subject of intensive investigation, both because of the molecules’ intrinsic physical and chemical properties, and for prospective applications in the emerging field of nanotechnology. Certain complex molecules are considered good candidates as basic building blocks for molecular electronics and nanomechanical devices. In general, molecular ordering on a surface is controlled by a delicate balance between intermolecular forces and molecule–substrate interactions. Under certain conditions, these interactions can be controlled to some extent, and sometimes even tuned by the appropriate choice of substrate material and symmetry. Several studies have indicated that, upon molecular adsorption, surfaces do not always behave as static templates, but may rearrange dramatically to accommodate different molecular species. In this context, it has been demonstrated that the scanning tunnelling microscope (STM) is a very powerful tool for exploring the atomic-scale realm of surfaces, and for investigating adsorbate–surface interactions. By means of high-resolution, fast-scanning STM unprecedented new insight was recently achieved into a number of fundamental processes related to the interaction of largish molecules with surfaces such as molecular diffusion, bonding of adsorbates on surfaces, and molecular self-assembly. In addition to the normal imaging mode, the STM tip can also be employed to manipulate single atoms and molecules in a bottom–up fashion, collectively or one at a time. In this way, molecule-induced surface restructuring processes can be revealed directly and nanostructures can be engineered with atomic precision to study surface quantum phenomena of fundamental interest. Here we will present a short review of some recent results, several of which were obtained by our group, in which several features of the complex interaction between large organic molecules and metal surfaces were revealed. The focus is on experiments performed using STM and other complementary surface-sensitive techniques.     

Molecular electronics: Scanning tunneling microscopy and single-molecule devices

Among switchable molecules, spin-crossover molecules are particularly appealing for molecular electronics as their change in spin state is associated with a large change in conductance and can also be used for molecular spintronic devices. In this article, we review the techniques that allow one to measure the electronic transport through single spin-crossover molecules. We particularly emphasize recent experiments using scanning tunneling microscopy and spectroscopy, where the spin state can be controlled by electric field, electric current or light.     

Coverage-dependent Orientations of Dy@C82 Molecules on Au(111) Surface

The adsorption and molecular orientation of Dy@C82 isomer I on Au(111) has been investi-gated using ultrahigh-vacuum scanning tunneling microscopy at 80 K. At low coverages, the Dy@C82 molecules tend to grow along the step edges of Au(111), forming small clusters and molecular chains. Adsorption of Dy@C82 on the edges is dominated by the fullerene-substrate interaction and presents various molecular orientations. At higher coverages, the Dy@C82 is found to form ordered islands consisting of small domains of equally oriented molecules. The Dy@C82 molecules in the islands prefer the adsorption configurations with the major C2 axis being approximately parallel to the surface of the substrate. Three preferable orientations of the Dy@C82 molecules are found in a two-dimensional hexagonal close packed overlayer. These observations are attributed to the interplay of the fullerene-substrate interaction and dipole-dipole interaction between the metallofullerenes.     

表面分子自组装结构的外界调控及STM研究进展

结合近年来国内外的研究工作, 概述了利用外界调控方式包括溶剂调控、热调控、光激发调控及电场/电位调控表面分子自组装结构的STM研究进展, 展望了该领域今后的研究方向.     

有机分子共振隧穿二极管

介绍了共振隧穿二极管(RTD)和有机分子共振隧穿二极管的结构、功能及工作原理，并对有机分子RTD的研究进展作了概述。     

Separation of a Racemic Mixture of Two-Dimensional Molecular Clusters by Scanning Tunneling Microscopy

Adsorption of sub-monolayer amounts of 1-nitronaphthalene (NN) onto Au(111) leads to the aggregation of NN decamers, which exhibit two-dimensional chirality and represent a racemic mixture. In analogy to Pasteur's experiment of 1848 a scanning tunneling microscope can be used to discriminate and separate the enantiomers on a molecular scale.