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Amplitude-mode spectroscopy of chemically injected and photogenerated charge carriers in semiconducting single-walled carbon nanotubes

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Nano Research 2023年第4期16卷 5619-5625页

作者： Shai R。Vardeny Alan Phillips Kira A。Thurman ZValy Vardeny Jeffrey L.Blackburn Division of Electrical Electronicand Infocommunications EngineeringOsaka University2-1 Yamada-okaSuitaOsaka 565-0871Japan Materials Chemistryand Computation Science DirectorateNational Renewable Energy LaboratoryGoldenCO 80401USA Department of Physics Colorado School of MinesGoldenCO 80401USA Department of Physics&Astronomy University of UtahSalt Lake CityUT 84112USA

In one-dimensional semiconductors such as conjugated polymers and semiconducting single-walled carbon nanotubes(s-SWCNTs),injected charge carriers(electrons or holes)can have profound impacts on both electronic conductivity and optical spectra,even at low carrier densities.Understanding charge-related spectral features is a key fundamental challenge with important technological implications.Here,we employ a systematic suite of experimental and theoretical tools to understand the mid-infrared charge signatures of heavily p-type doped polymer-wrapped s-SWCNTs.Across a broad range of nanotube diameters,we find that hole charge carriers induce strong Fano anti-resonances in mid-infrared transmission spectra that correspond to defect-related(D-band)and in-plane tangential(G-band)Raman-active vibrational modes,along with antiresonances arising from infrared(IR)-active polymer and SWCNT modes.We employ^(13)C isotope-labeled s-SWCNTs and a removable wrapping polymer to clarify the relative intensities,energies,and sources of all observed anti-resonances.Simulations performed with the“amplitude mode model”are used to quantitatively reproduce Raman spectra and also help to explain the outsized intensity of the D-band anti-resonance,relative to the G-band,observed for both moderately and degenerately doped s-SWCNTs.The results provide a framework for future studies of ground-and excited-state charge carriers in s-SWCNTs and a variety of low-dimensional materials.

关键词： carbon nanotubes doping charge carriers phonons electron-phonon coupling

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Tuning the type of charge carriers in N-heterocyclic carbene-based molecular junctions through electrodes

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Chinese Physics B 2020年第11期29卷 290-296页

作者：王明郎王传奎 School of Physics and Electronics Shandong Normal UniversityJinan 250358China

Designing tunable molecular devices with different charge carriers in single-molecule junctions is crucial to the nextgeneration electronic technology.Recently,it has been demonstrated that the type of charge carriers depends on and can be tuned by controlling the molecular length and the number of interfacial covalent bonds.In this study,we show that the type of charge carriers can also be tuned by controlling the material and shape of electrodes.N-heterocyclic carbenes(NHCs)have attracted attention because of their ability to form strong,substitutional inert bonds in a variety of metals.Also,NHCs are more stable than the widely used thiol group.Therefore,we use electrodes to tune the type of charge carriers in a series of NHCs with different side groups.The ab initio calculations based on non-equilibrium Green’s formalism combined with density functional theory show that the dominant charge carrier switches from electrons to holes when gold electrodes are changed into platinum ones.The nature of the charge carriers can be identified by variations in the transport spectra at the Fermi level(EF),which are caused by the side groups.The projections of transport spectra onto the central molecules further validate our inferences.In addition,the transmission coefficient at EF is found to be dependent on the atomic interface structure.In particular,for the NHC without methyl or ethyl side groups,connecting a protruding atom on the electrode surface significantly enhances the transportability of both electrode materials.Overall,this study presents an effective approach to modifying transport properties,which has potential applications in designing functional molecular devices based on NHCs.

关键词： molecular electronics charge carriers side groups non-equilibrium Green’s function

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Improving ionic conductivity of polymer-based solid electrolytes for lithium metal batteries

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Chinese Journal of Chemical Engineering 2022年第3期35卷 202-215页

作者： Q.Yang A.Wang J.Luo W.Tang Key Laboratory for Green Chemical Technology of Ministry of Education State Key Laboratory of Chemical EngineeringSchool of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China Shanghai Key Lab of Advanced High-Temperature Materials and Precision Forming School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Because of its superior safety and excellent processability,solid polymer electrolytes(SPEs)have attracted widespread attention.In lithium based batteries,SPEs have great prospects in replacing leaky and flammable liquid electrolytes.However,the low ionic conductivity of SPEs cannot meet the requirements of high energy density systems,which is also an important obstacle to its practical application.In this respect,escalating charge carriers(i.e.Li^(+))and Li^(+)transport paths are two major aspects of improving the ionic conductivity of SPEs.This article reviews recent advances from the two perspectives,and the underlying mechanism of these proposed strategies is discussed,including increasing the Li^(+)number and optimizing the Li^(+)transport paths through increasing the types and shortening the distance of Li^(+)transport path.It is hoped that this article can enlighten profound thinking and open up new ways to improve the ionic conductivity of SPEs.

关键词： Solid polymer electrolyte Ion conductivity charge carriers Transport paths Lithium battery

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Stable large-area monodomain in as-grown bulk ferroelectric single crystal Sn_(2)P_(2)S_(6)

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Journal of Advanced Dielectrics 2023年第3期13卷 1-7页

作者： Yingzhuo Lun Jiaqian Kang Wenfu Zhu Jianming Deng Xingan Jiang Cheng Zhu Qi Ren Xian Zi Ziyan Gao Tianlong Xia Zishuo Yao Xueyun Wang Jiawang Hong School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081P.R.China Guangdong Provincial Key Laboratory of Electronic Functional Materials and Devices Huizhou University HuizhouGuangdong 516007P.R.China Advanced Research Institute of Multidisciplinary Science Beijing Institute of Technology Beijing 100081P.R.China Beijing Key Laboratory of Optoelectronic Functional Materials&Micro-nano Devices Department of Physics Renmin University of ChinaBeijing 100872P.R.China School of Chemistry and Chemical Engineering Beijing Institute of Technology Beijing 100081P.R.China

Driven by the minimization of total energy,the multi-domain morphology is preferred in as-grown ferroelectrics to reduce the depolarization and strain energy during the paraelectric to ferroelectric phase transition.However,the complicated multi-domain is not desirable for certain high-performance ferroelectric electro-optic devices.In this work,we achieve a reproducible and stable large-area monodomain in as-grown bulk ferroelectric single crystal Sn_(2)P_(2)S_(6).The monodomain dominates the entire single crystal,which is attributed to the internal charge carriers from the photoexcited disproportionation reaction of Sn ions.The charge carriers effectively screen the depolarization field and therefore decrease the depolarization energy and facilitate the formation of monodomain.This work offers a potential approach for engineering bulk ferroelectrics with a stable monodomain,which is desirable for the high-performance ferroelectric electro-optic devices.

关键词： Sn_(2)P_(2)S_(6) monodomain ferroelectricity piezoelectric force microscopy disproportionation reaction charge carriers depolarization field screening

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charge storage mechanisms of cathode materials in rechargeable aluminum batteries

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Science China Chemistry 2021年第11期64卷 1888-1907页

作者： Jiashen Meng Lujun Zhu Aderemi B.Haruna Kenneth I.Ozoemena Quanquan Pang School of Materials Science and Engineering Peking UniversityBeijing100871China Beijing Key Laboratory of Theory and Technology for Advanced Batteries Materials Peking UniversityBeijing100871China Molecular Sciences Institute School of ChemistryUniversity of the WitwatersrandPrivate Bag 3PO WitsJohannesburg2050South Africa

Rechargeable aluminum batteries(RABs)have attracted great interest as one of the most promising candidates for large-scale energy storage because of their high volumetric capacity,low cost,high safety and the abundance of aluminum.However,compared with the aluminum anodes,the cathode materials face more problems including low specific capacity,relatively sluggish kinetics in most host structures and/or limited cycle lifespan,which pose the major challenge for RABs in further practical applications.During the past years,intensive efforts have been devoted to developing new cathode materials and/or designing engineered nanostructures to greatly improve RABs’electrochemical performances.In addition to nanotechnologybased electrode structure designs,the intrinsic chemical structures and charge storage mechanisms of cathode materials play an equally crucial role,if not more,in revolutionizing the battery performances.This review,here,focuses on current understandings into the charge storage mechanisms of cathode materials in RABs from a chemical reaction point of view.First,the fundamental chemistry,charge storage mechanisms and design principles of RAB cathode materials are highlighted.Based on different ion charge carriers,the current cathode materials are classified into four groups,including Al^(3+)-hosting,Al Cl_(4)^(-)-hosting,Al Cl_(2)^(+)/Al Cl_(2)^(+)-hosting,and Cl^(-)-hosting cathode materials.Next,the respective typical electrode structures,optimization strategies,electrochemical performances and charge storage mechanisms are discussed in detail to establish their chemistry-structure-property relationships.This review on current understandings of the cathode charge storage mechanisms will lay the ground and hopefully set new directions into the rational design of high-performance cathode materials in RABs,and open up new opportunities for designing new electrolyte systems with respect to the targeted cathode systems.

关键词： rechargeable aluminum batteries charge storage mechanisms cathode materials charge carriers large-scale energy storage

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Exciton emission dynamics in single InAs/GaAs quantum dots due to the existence of plasmon-field-induced metastable states in the wetting layer

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Chinese Physics B 2021年第9期30卷 552-557页

作者：黄君辉陈昊卓志瑶王健李叔伦丁琨倪海桥牛智川江德生窦秀明孙宝权 State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China College of Materials Science and Optoelectronic Technology University of Chinese Academy of SciencesBeijing 100049China Beijing Academy of Quantum Information Sciences Beijing 100193China

A very long lifetime exciton emission with non-single exponential decay characteristics has been reported for single InA-s/GaAs quantum dot(QD)samples,in which there exists a long-lived metastable state in the wetting layer(WL)through radiative field coupling between the exciton emissions in the WL and the dipole field of metal islands.In this article we have proposed a new three-level model to simulate the exciton emission decay curve.In this model,assuming that the excitons in a metastable state will diffuse and be trapped by QDs,and then emit fluorescence in QDs,a stretchedlike exponential decay formula is derived as I(t)=At^(β−1)e^(−(rt)^(β)),which can describe well the long lifetime decay curve with an analytical expression of average lifetime(τ)=1/rГ(1/β+1),where G is the Gamma function.Furthermore,based on the proposed three-level model,an expression of the second-order auto-correlation function g^(2)(t)which can fit the measured g^(2)(t)curve well,is also obtained.

关键词： quantum dots collective excitations charge carriers time resolved spectroscopy

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A Novel Electrochemical Method for Enhancing the Conductivity of Polyaniline Solid Matrices in Pre-Formed Films

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Chemical Research in Chinese Universities 2001年第Z1期17卷 43-页

作者： HAN Chien-Chung Department of Chemistry National Tsing Hua University

A fast, simple and environmentally friendly new electrochemical method capable of enhancing the conductivity of a preformed polyaniline film has been found. Utilizing this method of electrochemical forcing pre-treatment at a certain effective voltage, a polyaniline solid matrix can be made more conductive. For example, the conductivity of a preformed polyaniline film (as thick as 10 μm) can be easily enhanced by about an order of magnitude within a pretreatment time of only ca. 5 min. The UV-Vis-NIR and ESR spectroscopic evidences indicated that the charge carriers in the polyaniline matrix are more delocalized after such electrochemical pretreatments. The results of CV studies indicated that the resultant polyaniline film has higher charge transport efficiency and a greater redox rate. Such phenomenon may be linked with a possible backbone conformational change, as induced by this novel electrochemical pretreatment, within the solid matrix ofpolyaniline film.

关键词： polyaniline film solid matrix electrochemical method conformational change charge transport charge carriers method of

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