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Confined subdiffusion in three dimensions

Chinese Physics B 2014年第11期23卷 145-151页

作者：覃善林何勇 Hunan Key Laboratory for Super-microstructure and Ultrafast Process Institute of Super Microstructure and Ultrafast Process in Advanced MaterialsSchool of Physics and Electronics Central South University

Three-dimensional （3D） Fick＇s diffusion equation and fractional diffusion equation are solved for different reflecting boundaries. We use the continuous time random walk model （CTRW） to investigate the time-averaged mean square dis- placement （MSD） of a 3D single particle trajectory. Theoretical results show that the ensemble average of the time-averaged MSD can be expressed analytically by a Mittag-Leffler function. Our new expression is in agreement with previous formu- las in two limiting cases：（^-δ2） ~ △1 in short lag time and （^-δ2} ~ △1 -α in long lag time. We also simulate the experimental data of mRNA diffusion in living E. coli using a 3D CTRW model under confined and crowded conditions. The simulation results are well consistent with experimental results. The calculations of power spectral density （PSD） further indicate the subdiffsive behavior of an individual trajectory.

关键词： confined subdiffusion three dimensions time-averaged mean squared displacement

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The influence of phonon bath on the control of single photon

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Chinese Physics B 2015年第6期24卷 591-597页

作者：张威芦海涛 Institute of Super-Microstructure and Ultrafast Process in Advanced Materials School of Physics and ElectronicsCentral South University

The influence of vacuum fluctuation and phonon bath on the probability of single photon emission are both consid- ered in the two-level system model theoretically; by using the master equations and generating function method we get the analytical expression of the second-order fluorescence correlation function, probability of single photon emission, and Mandel＇s Q parameter. The results manifest that the coupling between the phonon bath and single photon source destroys the superposition state induced by the square laser pulse, the Rabi oscillation damped rapidly with the increasing of tem- perature. Theoretically, when the structure parameter of arsenide quantum dots tx scaled to O. 1 times of the sample, the critical coherence-temperature will rise up to hundreds of Kelvin, which means a step forward to the realization of coherent control of single photon source at room temperature.

关键词： single photon generating function photon bath phonon bath

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Electronic and transport properties of V-shaped defect zigzag MoS_2 nanoribbons

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Chinese Physics B 2014年第4期23卷 557-561页

作者：李新梅龙孟秋崔丽玲肖金徐慧 Institute of Super-microstructure and Ultrafast Process in Advanced Materials School of Physics and ElectronicsCentral South University School of Science Hunan University of Technology

Based on the nonequilibrium Green＇s function （NEGF） in combination with density functional theory （DFT） calcu- lations, we study the electronic structures and transport properties of zigzag MoS2 nanoribbons （ZMNRs） with V-shaped vacancy defects on the edge. The vacancy formation energy results show that the zigzag vacancy is easier to create on the edge of ZMNR than the armchair vacancy. Both of the defects can make the electronic band structures of ZMNRs change from metal to semiconductor. The calculations of electronic transport properties depict that the currents drop off clearly and rectification ratios increase in the defected systems. These effects would open up possibilities for their applications in novel nanoelectronic devices.

关键词： transport property zigzag MoS2 nanoribbons V-shaped defect first-principles

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Research on the protection of black phosphorus (BP) by the monolayer 7,7,8,8-tetracyanoquinodimethane (TCNQ)

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Synthetic Metals 2025年 312卷

作者： Zhao, Yuan Liu, Xiaoliang Yang, Baopeng Zhang, Jianhua Huang, Han Xie, Haipeng Niu, Dongmei Gao, Yongli Institute of Super-Microstructure and Ultrafast Process in Advanced Materials School of Physics Central South University Changsha410083 China Department of Physics and Astronomy University of Rochester RochesterNY14627 United States

Black phosphorus (BP) has attracted widespread attention in multiple research fields due to its excellent optoelectronic properties, such as adjustable direct bandgap, optical and electrical anisotropy. However, the poor air stability of BP limits its practical application. To protect BP through physical isolation and chemical passivation, a strong n-type organic semiconductor, 7,7,8,8-tetracyanoquinodimethane (TCNQ) was deposited on BP. The protective effect and the underlying mechanisms have been comprehensively investigated through various interface characterization techniques and density functional theory (DFT) calculations. It is found that the high adsorption energy (AE) between TCNQ and BP leads to the desorption of TCNQ from BP surface and TCNQ forms a dense monolayer (ML) film on BP in a stable lying configuration, which can protect BP from air exposure to some extent. Due to the higher work function (WF) of TCNQ compared to BP, the electron of BP at the interface are transferred to TCNQ through the quinone ring, resulting in a redistribution of electrons near the quinone ring of TCNQ and a shift of the C 1 s peak as well as the Raman peaks of C-C and C-C-H. The electron transfer from BP to TCNQ not only leads to an upward bending of the conduction band (CB) of BP at the interface, increasing the electron transfer barrier (ETB) between BP and O2, but also depletes the lone pair electrons of BP at the interface, protecting the shallow layer BP from oxidation and degradation. The ML of TCNQ and the shallow layer of BP significantly delays the contact between inner layer of BP and air, prolonging the stability of BP in air for more than 10 days. In addition, it is also confirmed that ML TCNQ has the minimal impact on the intrinsic structure and properties of BP. This work provides a new strategy for the protection and application of BP. © 2025 Elsevier B.V.

关键词： Dense and monolayer (ML) TCNQ film Desorption of TCNQ Physical isolation and chemical passivation Protection of BP

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Adsorption of oil contamination on water surface with nanoscale MoS2 powder and MoS2 self-reclamation and reutilization 3rd

Adsorption of oil contamination on water surface with nanosc...

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3rd Annual International Conference on Material Science and Environmental Engineering, ICMSEE 2015

作者： Li, X.H. Wang, P. Lv, B.S. He, J. Xiao, S. Department of Physics and Electronics Institute of Super-Microstructure and Ultrafast Process in Advanced Materials Central South University Changsha China

ISBN: (纸本)9781138029385

In this paper, the adsorption of oil contamination on water surface is studied using nanoscale MoS2 powder. After the application of MoS2 powder, the adsorption of oil contamination on water surface was found to be 2.1 times as its own weight at room temperature, with spheres, compound of MoS2 powder and oil sinking to the bottom of water. MoS2-oil spheres solidified after over 14-hour standing and can be physically recycled. After the high-heat treatment and grinding process, the recovery rate can reach up to 92%. The secondary oil absorption capacity can reach up to 90% as at the first time. The characteristics of this study are the observation of nanoscale MoS2 adsorbing oil contamination and sinking to the bottom automatically. This method can be used as a possible application in the treatment of oil contamination in a closed pipeline. Meanwhile, this study lays the foundation for oil contamination treatment with MoS2 in the future. © 2016 Taylor and Francis Group, London.

关键词： Sulfur compounds

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Random Copolymers Based on Thieno[3,4-c]pyrrole-4,6-dione and Isoindigo Building Blocks for Polymer Solar Cells

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Chinese Journal of Chemistry 2014年第6期32卷 521-526页

作者： Ping Deng Jian Xiong Shugang Li Yibing Wu Junliang Yang Qing Zhang School of Chemistry and Chemical Engineering Shanghai Jiao Tong UniversityShanghai 200240China Institute of Super Microstructure and Ultrafast Process in Advanced Materials School of Physics and ElectronicsCentral South UniversityChangshaHunan 410083China

Three random conjugated polymers,RP-TiI,RP-2TiI and RP-TVTiI based on both thieno[3,4-c]pyrrole-4,6-dione and isoindigo units have been synthesized by Stille cross-coupling *** optical and electrochemical properties of new polymers have been *** resulted polymers showed broad absorption spectra and appropriate energy levels for polymer solar cell *** bulk heterojunction devices based on the blend of the polymer RP-TiI and PC_(61)BM showed a power conversion efficiency of 1.75%.

关键词： thieno[3,4-c]pyrrole-4 6-dione isoindigo random copolymers polymer solar cells

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Substrate-dependent Growth of CH3NH3PbI3Films Deposited by Vacuum Evaporation 8

Substrate-dependent Growth of CH3NH3PbI3Films Deposited by V...

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8th Annual International Conference on Material Science and Engineering, ICMSE 2020

作者： Lu, Ying Han, Qiang Zhao, Yuan Yang, Chenggang Li, Youzhen Liu, Xiaoliang Institute of Super-Microstructure and Ultrafast Process in Advanced Materials School of Physics and Electronics Central South University Changsha410083 China

CH3NH3PbI3 (MAPbI3) films were prepared by dual-source vacuum evaporation on Au, poly(3,4-ethylenedioxythiophene) (PEDOT), and indium-tin-oxide(ITO) with the similar deposition parameters. The films were characterized with X-ray diffraction (XRD), steady-state photoluminescence (PL) and Raman spectroscopy. The interface electronic structures of co-evaporated MAPbI3 films on different substrates were studied with ultraviolet photoemission spectroscopy (UPS) and X-ray photoemission spectroscopy (XPS). The research indicates that Au is more suitable for the film growth than the other substrates, especially when the film is very thin. The poor adsorption of the precursors may make it difficult to form MAPbI3 thin film on ITO. Furthermore, it is found that the charge transfer efficiency at the interface between PEDOT and MAPbI3 is relatively high, which indicates that PEDOT can act as an effective hole transport layer for MAPbI3-based devices. © Published under licence by IOP Publishing Ltd.

关键词： Vacuum evaporation

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Polarization dependent nonlinear absorption in Au nanowire array

Polarization dependent nonlinear absorption in Au nanowire a...

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作者： Xing, Ruo Chen Xiao, Si He, Jun Institute of Super-microstructure and Ultrafast Process in Advanced Materials School of Physics and Electronics Central South University Changsha 410083 China Hunan Key Laboratory for Super-microstructure and Ultrafast Process Central South University Changsha 410083 China

ISBN: (纸本)9783038351214

The polarization dependent nonlinear absorption was observed in ordered Au nanowire array. The linear and nonlinear polarized absorption at 780 nm is investigated by Z-scan. When the angle between the polarization direction of input laser and the long axis of Au nanowires is 90°(perpendicular), the linear absorption reaches the maximum and the nonlinear absorption reaches the minimum. The nonlinear absorption coefficient β decreases from positive to negative as the angle increase from 0° to 90°. There may be two nonlinear absorption mechanisms resulting in this phenomenon: two-photon absorption and saturable absorption in nanoscale. © (2014) Trans Tech Publications, Switzerland.

关键词： Polarization

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Characteristics research of gallium arsenide solar cells under femtosecond laser illumination

Characteristics research of gallium arsenide solar cells und...

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作者： Xiao, Si Gao, Yi Tan Tian, Xiu Qin He, Jun Institute of Super-microstructure and Ultrafast Process in Advanced Materials Department of Physics and Electronics Central South University Changsha 410083 China Hunan Key Laboratory for Super-microstructure and Ultrafast Process Central South University Changsha 410083 China

ISBN: (纸本)9783038351214

Femtosecond laser with ultrashort pulse (≤35fs) is used to investigate the damage threshold and light-to-electric conversion efficiency of gallium arsenide solar cells. Different from nanosecond or picosecond lasers, the damage threshold of the solar cell illuminated by femtosecond laser is slightly higher than that under the illumination of continuous-waves laser with the same wavelength. Because the thermal non-equilibrium effect becomes obvious, heat conduction phenomenon no longer obeys the law of Fourier, when the heating pulse time of femtosecond laser is equal to or shorter than the electron- phonon coupling time. The photovoltaic properties of gallium arsenide solar cells under femtosecond pulse laser illumination are measured. The device shows better short circuit current and the light-to-electric conversion efficiency under femtosecond pulse laser than that under continuous-waves laser of the same wavelength. © (2014) Trans Tech Publications, Switzerland.

关键词： Solar cells

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Fano Resonance Effect in CO-Adsorbed Zigzag Graphene Nanoribbons

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Chinese Physics Letters 2017年第9期34卷 91-94页

作者： Gao Wang Meng-Qiu Long Dan Zhang Advanced Research Center Central South University Changsha 410083 Institute of Super Microstructure and Ultrafast Process Central South University Changsha 410083 School of Science Hunan University of Technology Zhuzhou 412007

Quantum interference plays an important role in tuning the transport property of nano-devices. Using the non- equilibrium Green＇s Function method in combination with density functional theory, we investigate the influence to the transport property of a CO molecule adsorbed on one edge of a zigzag graphene nanoribbon device. Our results show that the CO molecule-adsorbed zigzag graphene nanoribbon devices can exhibit the Fano resonance phenomenon. Moreover, the distance between CO molecules and zigzag graphene nanoribbons is closely related to the energy sites of the Fano resonance. Our theoretical analyses indicate that the Fano resonance would be attributed to the interaction between CO molecules and the edge of the zigzag graphene nanoribbon device, which results in the localization of electrons and significantly changes the transmission spectrum.

关键词： DOS Fano Resonance Effect in CO-Adsorbed Zigzag Graphene Nanoribbons CO

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