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

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

大熊猫粪便皮质醇激素分布与取样对策

粪便皮质醇激素对衡量动物应激强度具有较好的指示作用,但其检测准确性受诸多因素影响。为了评估不同取样方式对大熊猫(Ailuropoda melanoleuca)粪便皮质醇测定产生的影响,将粪便横向纵向四等分分割,采用冻干研筛法与酶联免疫吸附法(ELISA)处理每部分粪便和测定激素含量,旨在分析粪便激素分布情况以进一步探讨取样对策。结果显示:每部分粪便的皮质醇含量无显著差异(df=3,F=0.033,P=0.992),粪便在四等分处理下的激素分布比较均匀,即每部分粪便激素均能在一定程度上代表整体水平。1/2取样所产生的变异系数小于1/4取样,前者的检测准确性更高。粪便湿重与尺寸大小存在显著正相关性(r=0.897,Py=2.3x-29.3(y为粪便湿重,x为粪便大小,R2=0.804,F=418.846,P<0.001)。粪便干重由粪便类型、尺寸和含水率决定。在野外工作中,建议采用纵向1/2的取样对策

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

Prediction of Energy Resolution in the JUNO Experiment

International audienceThis paper presents the energy resolution study in the JUNO experiment, incorporating the latest knowledge acquired during the detector construction phase. The determination of neutrino mass ordering in JUNO requires an exceptional energy resolution better than 3% at 1 MeV. To achieve this ambitious goal, significant efforts have been undertaken in the design and production of the key components of the JUNO detector. Various factors affecting the detection of inverse beta decay signals have an impact on the energy resolution, extending beyond the statistical fluctuations of the detected number of photons, such as the properties of liquid scintillator, performance of photomultiplier tubes, and the energy reconstruction algorithm. To account for these effects, a full JUNO simulation and reconstruction approach is employed. This enables the modeling of all relevant effects and the evaluation of associated inputs to accurately estimate the energy resolution. The study reveals an energy resolution of 2.95% at 1 MeV. Furthermore, the study assesses the contribution of major effects to the overall energy resolution budget. This analysis serves as a reference for interpreting future measurements of energy resolution during JUNO data taking. Moreover, it provides a guideline in comprehending the energy resolution characteristics of liquid scintillator-based detectors