Single Molecular Junction Construction and Comprehensive Characterization by Mechanically Controllable Break Junction Method

高效可靠的精确测量技术是实现各类科学发现的重要前提。纳米尺度乃至单 分子水平的测量技术，是该尺度下分子材料和分子器件的直接表征手段，可为从 分子水平设计材料、构筑器件提供重要实验依据。迄今单分子电学测量技术致力 于为传统硅基半导体器件小型化提供自下而上的分子电子学的替代解决方案，另 一方面，单分子尺度下的物理化学性质可由其电学性质体现，对基础研究领域中 的单分子科学、自组装科学和有机合成化学均有很好的借鉴和助推作用。然而可 靠、高效、高灵敏度的单分子电学测量技术的发展及相关科研仪器研制具有很大 的挑战性，即需要发展一套合适、高效的表征手段来提高相同分子结体系在不同 构筑方法及不...Efficient and reliable measuring techniques are important prerequists in scientific discoveries, those techniques down to nanometer even single-molecule scale are direct characterization means to single-molecular materials and devices, which provide vital experimental evidences for mateials and devices designing. Nowadays, single-molecule electrical measuring techniques offer opportunities as ...学位：理学博士院系专业：化学化工学院_物理化学学号：2052010015366

Anti-resonance features of destructive quantum interference in single-molecule thiophene junctions achieved by electrochemical gating

基于单个有机分子来构筑电子器件为电子器件微型化提供潜在技术方案。本研究发展了可集成电化学门控的单分子电子器件测试芯片技术和科学仪器方法，在实验和理论两个层面对具有相消量子干涉效应的噻吩衍生物分子器件的电输运过程进行了电化学调控研究，从而首次在室温下实现了对单分子电子器件中量子干涉效应的反共振现象的直接观测和调控，为制备基于量子干涉效应的新型分子材料和器件提供了全新的设计思路和策略。该研究充分展示了电化学调控技术在信息材料和器件领域的重要应用潜力，也体现了我校固体表面物理化学国家重点实验室在电化学研究和科学仪器研发领域的技术积累，以及面向科学前沿开展交叉学科探索的研究特色。 该研究工作是在洪文晶教授、上海电力大学陈文博教授、英国兰卡斯特大学Colin Lambert教授指导下完成的。化学化工学院博士生白杰和李晓慧为论文的共同第一作者，刘俊扬副研究员、师佳副教授、研究生唐永翔、刘帅、黄晓娟、谭志冰和萨本栋微纳研究院的杨杨副教授等也参与了研究工作。田中群教授和毛秉伟教授为该工作提供了重要指导。【Abstract】Controlling the electrical conductance and in particular the occurrence of quantum interference in single-molecule junctions through gating effects, has potential for the realization of high-performance functional molecular devices. In this work, we used an electrochemically-gated, mechanically-controllable break junction technique to tune the electronic behaviour of thiophene-based molecular junctions that show destructive quantum interference (DQI) features. By varying the voltage applied to the electrochemical gate at room temperature, we reached a conductance minimum that provides direct evidence of charge transport controlled by an anti-resonance arising from DQI. Our molecular system enables conductance tuning close to two orders of magnitude within the non-faradaic potential region, which is significantly higher than that achieved with molecules not showing DQI. Our experimental results, interpreted using quantum transport theory, demonstrate that electrochemical gating is a promising strategy for obtaining improved in-situ control over the electrical performance of interference-based molecular devices.This research was supported by the National Key R&D Program of China (2017YFA0204902), National Natural Science Foundation of China (21722305, 21673195, 21503179, 21703188), the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning, Natural Science Foundation of Shanghai (17ZR1447100), Science and Technology Commission of Shanghai Municipality (14DZ2261000), China Postdoctoral Science Foundation (2017M622060) for funding work in Xiamen. It was also supported by EU Horizon 2020 project QuIET under grant agreement no. 767187EC FP7 ITN ‘MOLESCO’ project no. 606728 and UK EPSRC grants EP/N017188/1 and EP/M014452/1 and Leverhulme Trust (Leverhulme Early Career Fellowships no. ECF-2017-186 and ECF-2018-375) for funding instrumentation used in Lancaster. It was also supported by Hungarian and Czech Academies of Sciences (P2015-107) and Hungarian Research Foundation (OTKA 112034) for funding instrumentation used in Hungary. The authors thank Z.-Q. Tian and B.-W. Mao, Xiamen University, for useful discussions. 该工作获得科技部国家重点研发计划课题（2017YFA0204902），国家自然科学基金委优秀青年科学基金等项目（21722305、21673195、21703188、21503179）以及中国博士后科学基金（2017M622060）等项目的资助，也得到了固体表面物理化学国家重点实验室、能源材料化学协同创新中心的支持

Transition from tunneling leakage current to molecular tunneling in single-molecule junctions

数十年来，半导体工业一直遵循基于“摩尔定律”所设定的发展蓝图，逐步提升集成电路芯片上晶体管的集成度和运行速度，减小器件尺寸。为探索这一尺寸极限，课题组基于机械可控裂结技术自主开发了具有飞安级电学测量和亚纳米级位移控制灵敏度的科学仪器，在国际上首次获取了一系列具有不同重复单元的寡聚苯乙炔类分子电导随电极间距的演变关系，并发现随着电极间距的缩小，器件电输运由通过分子器件电流占主导逐步转变到由隧穿漏电流占主导。对于本研究中具有最小尺寸的寡聚苯乙炔分子器件，其由于隧穿漏电流所制约的尺寸极限可小至0.66 nm，预示了有机分子器件在未来电子器件小型化方面具有重要的应用潜力。 这一研究工作是在化学化工学院洪文晶教授、萨本栋微纳研究院杨扬助理教授以及英国Durham University的MartinR. Bryce教授共同指导下完成的。能源材料化学协同创新中心iChEM Fellow刘俊扬博士为论文第一作者，博士研究生郑珏婷、李瑞豪和硕士研究生黄晓艳、唐永翔、皮九婵、本科生王飞等参与了研究工作。田中群教授、毛秉伟教授和师佳副教授为论文工作提供了重要指导。【Abstract】The tunneling leakage current will be a major quantum obstacle during miniaturization in the semiconductor industry down to the scale of several nanometers. At this scale, to promote charge transport and overcome the tunneling leakage current between the source and drain terminals, molecular electronic junctions offer opportunities by inserting molecules between these two electrodes. Employing a series of oligo(aryleneethynylene) (OAE) molecules, here we investigate the transition from tunneling leakage current to molecular tunneling in the single-molecule devices using mechanically controllable break junction (MCBJ) technique, and the transition distances of the OAE molecular junctions were determined and even down to 0.66 nm for OAE2 molecular junction, which demonstrates that the intrinsic charge transport properties of a single-molecule device can be outstripped from the tunneling leakage current. Consequently, molecular electronic devices show the potential to push the ultimate limit of miniaturization to the scale of several angstroms.This work was supported by the National Key R&D Program of China (2017YFA0204902). This work was also generously supported by the Young Thousand Talent Project of China, the EC FP7 ITN “MOLESCO” project number 606728, the National Natural Science Foundation of China (nos. 21703188, 21673195, 21503179), and the China Postdoctoral Science Foundation (2017M622060). 该工作获得科技部国家重点研发计划课题（2017YFA0204902），国家自然科学基金委（21673195、21703188、21503179）以及中国博士后科学基金（2017M622060）等项目的资助，也得到了固体表面物理化学国家重点实验室、能源材料化学协同创新中心的支持

Electric-field-induced selective catalysis of single-molecule reaction

随着单分子电学检测技术的迅速发展，分子电子学的研究不再局限于分子电子学器件的构筑及其电学性质的测量，而且扩展到单分子尺度化学反应过程的探索。然而目前相关的研究仍然局限于理论计算方面，在单分子尺度上实时监测和调控化学反应的活性和选择性是化学领域的长期目标和挑战。针对这一挑战，洪文晶教授课题组与程俊教授课题组合作，自主研发了精密科学仪器，将单个有机分子定向连接在两个末端尺寸为原子级的电极之间，解决了化学反应中分子取向控制的问题.理论计算结果证实了定向电场可以有效地稳定化学反应的过渡态，从而降低反应能垒。该研究工作在化学化工学院洪文晶教授、程俊教授、能源材料化学协同创新中心（iChEM）刘俊扬副研究员的共同指导下完成，由硕士研究生黄晓艳、iChEM博士研究生唐淳、博士研究生李洁琼以及兰州大学的陈力川博士作为共同第一作者，化学化工学院师佳副教授、陈招斌高级工程师、夏海平教授和田中群教授，萨本栋微纳研究院杨扬副教授、环境与生态学院白敏冬教授以及兰州大学张浩力教授参与了研究工作的讨论并给予指导，博士后乐家波、博士研究生郑珏婷、张佩（已毕业）、李瑞豪、李晓慧也参与了研究工作。Oriented external electric fields (OEEFs) offer a unique chance to tune catalytic selectivity by orienting the alignment of the electric field along the axis of the activated bond for a specific chemical reaction; however, they remain a key experimental challenge. Here, we experimentally and theoretically investigated the OEEF-induced selective catalysis in a two-step cascade reaction of the Diels-Alder addition followed by an aromatization process. Characterized by the mechanically controllable break junction (MCBJ) technique in the nanogap and confirmed by nuclear magnetic resonance (NMR) in bottles, OEEFs are found to selectively catalyze the aromatization reaction by one order of magnitude owing to the alignment of the electric field on the reaction axis. Meanwhile, the Diels-Alder reaction remained unchanged since its reaction axis is orthogonal to the electric fields. This orientation-selective catalytic effect of OEEFs reveals that chemical reactions can be selectively manipulated through the elegant alignment between the electric fields and the reaction axis.This work was supported by the National Key R&D Program of China (2017YFA0204902), the National Natural Science Foundation of China (21722305, 21703188, 21673195, 21621091, 51733004, 51525303, and 91745103), the China Postdoctoral Science Foundation (2017M622060), and the Young Thousand Talents Project of China. 该工作得到国家自然科学基金委（21722305、21703188、21673195、51733004、51525303、91745103），国家重点研发计划课题（2017YFA0204902），中国博士后面上基金（2017M622060）的资助，以及固体表面物理化学国家重点实验室、醇醚酯化工清洁生产国家工程实验室、能源材料化学协同创新中心的支持

Identifying the Conformational Isomers of Single-Molecule Cyclohexane at Room Temperature

构象异构是化学中的基本问题。然而对于环己烷等柔性分子，由于其在室温下极快的互变异构过程，基于系综的表征方法（如核磁等）只能得到所有构象平均贡献的结果。为了应对这一挑战，化学化工学院洪文晶教授与夏海平教授课题组为在室温条件下对柔性分子构象的定量分析与表征这一挑战，课题组成功实现了在室温条件下对环己烷两种椅式构象的电学表征与比例识别。同时，通过纳米电极间隙对分子的限域作用，发现在宏观尺度下极不稳定的扭船式中间体得以在单分子尺度稳定存在，这为不稳定中间体的研究提供了重要表征方法。 这一研究工作是在化学化工学院洪文晶教授、夏海平教授共同指导下完成的，iChEM直博生唐淳与化工系研究生唐永翔为论文共同第一作者。师佳副教授与刘俊扬副研究员为该工作提供了指导，博士后陈志昕、博士研究生陈李珏以及研究生叶艺玲、严哲玮、张珑漪共同参与了该工作。【Abstract】Isomerism reflects the ubiquitous nature that molecules with the same molecular formula show different structures. The interconversion between conformational isomers of flexible molecules is quite fast owing to the low barriers of around 10 kcal mol−1, leading to average signal contributed by all the possible isomers characterized by ensemble methods. On this account, identifying the conformational isomers of flexible molecules at room temperature has a substantial challenge. Here, we develop a single-molecule approach to identify the conformational isomers of cyclohexane at room temperature through the single-molecule electrical characterization. By noise analysis and feature extraction of the conductance of single-molecule junctions, we quantificationally identified two chair isomers of cyclohexane at room temperature, while such identification is only feasible at low temperatures by ensemble characterization. The strategy to apply the single-molecule approach to identify conformational isomers paves the avenue to investigate the isomerization of flexible molecules beyond the ensemble methods.This work was supported by the National Natural Science Foundation of China (nos, 21722305, 21673195, 21703188, and U1705254), the National Key R&D Program of China (2017YFA0204902), China Postdoctoral Science Foundation (no. 2017M622060), and the Fundamental Research Funds for Xiamen University (20720190002).该工作获得了科技部国家重点研发计划、国家自然科学基金等项目的资助，也得到了固体表面物理化学国家重点实验室、能源材料化学协同创新中心的支持

Room-temperature quantum interference in single perovskite quantum dot junctions

钙钛矿材料由于其高量子产率、载流子迁移率和独特的光致发光特性而在光电材料领域存在诸多潜在的重要应用。研究钙钛矿材料在纳米尺度下电荷输运的独特尺寸效应对钙钛矿光电器件的设计和开发具有重要的指导意义。洪文晶教授课题组基于机械可控裂结技术自主研发了具有皮米级位移调控灵敏度和飞安级电学测量精度的精密科学仪器，对南开大学李跃龙副教授团队合成的钙钛矿量子点进行了深入表征，研究工作成功将量子干涉的研究体系拓展至在光电领域具有重要应用的钙钛矿材料领域，为未来制备基于量子干涉效应的新型钙钛矿器件提供了一种全新的思路。 这一跨学科国际合作研究工作是在化学化工学院洪文晶教授、英国Lancaster 大学物理系Colin J. Lambert教授以及南开大学电子信息与光电工程学院李跃龙副教授的共同指导下完成的。化工系硕士研究生郑海宁、Lancaster University大学Songjun Hou博士、南开大学硕士研究生辛晨光为论文第一作者。博士后林禄春，博士研究生谭志冰、郑珏婷，硕士研究生蒋枫、张珑漪，本科生何文翔、李庆民等参与了论文的研究工作。刘俊扬特任副研究员、师佳副教授和萨本栋微纳米研究院杨扬副教授也参与了部分指导工作。The studies of quantum interference effects through bulk perovskite materials at the Ångstrom scale still remain as a major challenge. Herein, we provide the observation of roomtemperature quantum interference effects in metal halide perovskite quantum dots (QDs) using the mechanically controllable break junction technique. Single-QD conductance measurements reveal that there are multiple conductance peaks for the CH3NH3PbBr3 and CH3NH3PbBr2.15Cl0.85 QDs, whose displacement distributions match the lattice constant of QDs, suggesting that the gold electrodes slide through different lattice sites of the QD via Auhalogen coupling. We also observe a distinct conductance ‘jump’ at the end of the sliding process, which is further evidence that quantum interference effects dominate charge transport in these single-QD junctions. This conductance ‘jump’ is also confirmed by our theoretical calculations utilizing density functional theory combined with quantum transport theory. Our measurements and theory create a pathway to exploit quantum interference effects in quantum-controlled perovskite materials.This work was supported by the National Key R&D Program of China (2017YFA0204902, 2014DFE60170, 2018YFB1500105), the National Natural Science Foundation of China (Nos. 21673195, 21503179, 21490573, 61674084, 61874167), the Open Fund of the Key Laboratory of Optical Information Science & Technology (Nankai University) of China, the Fundamental Research Funds for the Central Universities of China (63181321, 63191414, 96173224), and the 111 Project (B16027), the Tianjin Natural Science Foundation (17JCYBJC41400), FET Open project 767187—QuIET, the EU project BAC-TO-FUEL and the UK EPSRC projects EP/N017188/1, EP/M014452/1. 该工作得到国家重点研发计划课题（2017YFA0204902）、国家自然科学基金（21673195、21503179、21490573）、厦门大学“人工智能分析引擎”双一流重大专项等项目的资助，也得到了固体表面物理化学国家重点实验室、能源材料化学协同创新中心的支持

Mechanism and Characterization of Electron Transport Through Metal/Molecule/Metal Junctions

金属/分子/金属结是分子电子学中的基本单元.根据电子的相位是否发生改变,分子结中的电子输运可以分为相干输运和非相干输运两类.在实验上,分子结的表征方法可以分为电学性质表征和非电学性质表征两类.本文借助能级图,首先对分子结的电子输运机理作了简明解释.在此基础上,结合文献报道和本课题组此前的工作,对分子结的一些常用电学表征方法,包括电流-电压特性曲线、电流-时间曲线、电导统计柱状图、转变电压谱、散粒噪声测试、非弹性电子隧道谱和热电效应法进行了介绍.Although molecular electronics emerged several decades ago,it is still concerning about fundamental issues so far.Metal/molecule/metal junction is a conceptually basic unit in molecular electronics.The mechanism of electron transport through metal/molecule/metal junction has attracted great interest.In general,the mechanisms for electron transport through metal/molecule/metal junctions can be divided into two categories: coherent transport and non-coherent transport according to the phase change of tunneling electrons.In this review,the electron transport mechanism is illustrated briefly by employing energy diagrams.Moreover,several extensively measured approaches for studying metal/molecule/metal junctions,including I-V characteristic curve,I-t trace and conductance histogram,transition voltage spectroscopy,shot noise,inelastic electron tunneling spectroscopy,and thermoelectricity are introduced through referring to some recent publications including our works.科技部-国家重大科学仪器设备开发专项项目(批准号:2011YQ030124); 国家自然科学基金(批准号:21321062;21373172)资助~

Study on PCR-ELISA for the Detection of Genetically Modified Organisms Products

建立并优化了转基因大豆与玉米的DNA提取方法,针对CaMV35S启动子和T-NOS终止子的序列特点设计特异性引物与探针,应用PCR-ELISA检测技术,建立了转基因大豆与玉米中常用外源基因的快速检测体系,并应用于进出境产品的转基因检测实际工作中。结果表明,建立的PCR-ELISA法具有操作简便、灵敏特异、结果准确的优点,可对转基因大豆、玉米及其它转基因产品进行定性和定量检测。The methods of extracting DNAfromgenetically modified organisms (GMOs )were studied and ob-timized.According to the characteristics of CaMV 35S promoter&T -NOS te rminator introduced into GMOs ,PCR -enzyme linked immunosorbent assay(PCR -ELISA)methods were suitable for screening of transgenic elements andtherefore established.Withthis methodwe analyzedsoybeans andcorns.The results showedthatthemethods of PCR -ELISAwere simple,rapid and reliable for qualitative a nd quantificational analysis of GMOs.厦门市科技计划资助项目(3502Z2001109

Protonation Tuning of Quantum Interference in Azulene-Type Single-Molecule Junctions

单分子尺度电输运性质的研究为从分子水平计分子材料和器件提供了直接实验依据。在单分子尺度，因电子不同传输路径引起的量子干涉效应对单分子尺度电输运性质有显著影响，而如何有效调控量子干涉效应从而控制分子器件电输运性质仍然是分子电子学领域重大挑战之一。在该项研究工作中，通过对奥甘菊系列分子单分子尺度电输运性质研究发现，5,7位取代的奥甘菊电输运能力低于其他取代位点奥甘菊分子，存在明显的相消量子干涉效应。奥甘菊系列分子作为刺激响应结构单元在未来分子器件和材料中有重要的应用前景，同时基于质子化地量子干涉效应调控也为单分子器件电输运性质的未来设计提供了新思路。 这一跨学科研究工作是在我院洪文晶教授、中科院化学所张德清研究员及刘子桐副研究员、英国Lancaster大学Colin Lambert教授的共同指导下完成的。我院2014级硕士研究生杨国钢、英国Lancaster大学物理系博士后Sara Sangtarash博士作为共同第一作者，我院研究生李晓慧、谭志冰、李瑞豪、郑珏婷等共同完成，师佳副教授、刘俊扬特任副研究员和微纳院杨扬助理教授也参与了部分研究工作。【Abstract】The protonation of azulene derivatives with quantum interference effects is studied by the conductance measurements of single-molecule junctions. Three azulene derivatives with different connectivities are synthesized and reacted with trifluoroacetic acid to form the protonated states. It is found that the protonated azulene molecular junctions produce more than one order of magnitude higher conductance than the neutral states, while the molecules with destructive interference show more significant changes. These experimental observations are supported by our recently-developed parameter free theory of connectivity, which suggests that the largest conductance change occurs when destructive interference near the Fermi energy in the neutral state is alleviated by protonation.这一工作得到了国家重点研发计划（2017YFA0204902）、自然科学基金项目（21673195，21190032，21372226，21503179）、千人计划青年项目、固体表面物理化学国家重点实验室、能源材料化学协同创新中心（2011-iChEM）以及石墨烯工程与产业研究院的支持