Yichun Liu

Northeast Normal University, Hsin-ching, Jilin Sheng, China

Are you Yichun Liu?

Claim your profile

Publications (228)721.83 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Coexistence of nonvolatile and volatile resistive switching behaviors was demonstrated in Cu/amorphous carbon/Pt sandwich-structure memory devices by adjusting compliance currents (CCs) to control the size of Cu conductive filament (CF). It was observed that the retention time of the volatile switching strongly depends on the CF’s size, and can be tuned in a wide range from hundreds of milliseconds to tens of seconds. When the nanoscale CF contains only a small number of Cu atoms, the conductance quantization occurs in the relaxation process of resistance state. By quantitatively studying the dependence of relaxation time on CF’s size and temperature, the volatile behavior can be well understood within the framework of the Rayleigh instability, where the Cu-CF spontaneously dissolves to minimize the surface energy. The observed nonvolatile/volatile behaviors, as well as the spontaneous relaxation effect, bear many resemblances to the long-term/short-term plasticity of biological synapses, and thus can be fully utilized to develop artificial synaptic devices.
    Carbon 09/2015; 91. DOI:10.1016/j.carbon.2015.04.031 · 6.20 Impact Factor
  • Applied Surface Science 09/2015; DOI:10.1016/j.apsusc.2015.09.182 · 2.71 Impact Factor
  • Applied Physics Express 09/2015; 8(9):095202. DOI:10.7567/APEX.8.095202 · 2.37 Impact Factor
  • Source
    Mingyi Zhang · Changlu Shao · Xin Zhang · Yichun Liu
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, a two-step synthesis route combining an electrospinning technique and solvothermal method has been accepted as a straightforward protocol for the exploitation of BiOCl-carbon nanofibers (CNFs) hierarchical heterostructures. Photocatalytic tests showed that the BiOCl-CNFs heterostructures possess a much higher degradation rate of 4-nitrophenol (4-NP) than pure BiOCl. The enhanced photocatalytic activity could be attributed to the effective separation of photogenerated carriers driven by the photoinduced potential difference generated at the BiOCl-CNFs heterojunction interface. The ·OH radicals played a critical role in the photocatalytic degradation of 4-NP over the BiOCl–CNFs heterostructures. Moreover, the heterostructures could be reclaimed easily by sedimentation without a decrease of the photocatalytic activity.
    CrystEngComm 08/2015; DOI:10.1039/C5CE01012H · 4.03 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The conductive, transparent, and flexible SnO2:Sb single-crystal nanowires are shown as electrodes for F16CuPc single-crystal nanowire devices on the flexible plastic which includes anisotropic-transport OFETs, electrode-movable OFETs, and p-n junction photovoltaic devices. The SnO2:Sb nanowires provide the good energy level match and the excellent soft contact with F16CuPc nanowire, leading to the multifacet applications of the SnO2:Sb nanowire in nanowire electronics and optoelectronics, and the high device performance. Combined with their good size compatibility these results shows that the conductive SnO2:Sb single-crystal nanowire opens a window into the fundamental understanding of the intrinsic properties of highly ordered organic semiconductors, optimization and miniaturization of the organic nanocircuits, and development of new-generation flexible organic nanodevice.
    08/2015; DOI:10.1039/C5TC01920F
  • Changhua Wang · Xintong Zhang · Yichun Liu
    Applied Surface Science 08/2015; DOI:10.1016/j.apsusc.2015.08.055 · 2.71 Impact Factor
  • Guiru Xue · Qingxin Tang · Yanhong Tong · Yichun Liu
    [Show abstract] [Hide abstract]
    ABSTRACT: Conventional graphene nanoribbon (GNR) field-effect transistor (FET) fabrication involved the wet process with the separated nanoribbon formation and device fabrication. Here, we demonstrate one simple and novel non-solution method to integrate the GNR formation and the FET fabrication, where a gold film is used as mask for electrode deposition, following by using a SnO2 nanoribbon as mask for the formation of GNR. The channel length and width can be controlled by the widths of the gold film and the SnO2 nanoribbon, respectively. It is found that the GNR with the width up to 330 nm presents the promising ambipolar field-effect properties in air ambient, the hole and electron mobilities are respectively as high as 904 and 703 cm2 V−1 s−1, which benefits from the all dry process for both GNR fabrication and device fabrication.
    Synthetic Metals 07/2015; 205. DOI:10.1016/j.synthmet.2015.03.024 · 2.25 Impact Factor
  • The Journal of Physical Chemistry C 07/2015; DOI:10.1021/acs.jpcc.5b04409 · 4.77 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Despite the excellent photo-generated charge separation and transport properties of 1D rutile TiO2 nanowire (NW) array, insufficient light harvesting due to low surface area is a key factor that limiting the photovoltaic performance of TiO2 NW-based solar cells. Herein, we apply semiconductor Sb2S3 as light absorber and sprayed p-CuI as hole conductor for TiO2 NW solar cells. The Sb2S3-sensitized device displays significantly improved light absorption than its corresponding dye-sensitized device, with a peak incident-photon-to-current conversion efficiency (IPCE) of 64%. Moreover, CuI film deposited by spray technique enables improved pore filling and better electrical contact between Sb2S3 absorber and CuI, as well as CuI crystals themselves, and facilitates hole transfer from Sb2S3 to CuI crystals and hole transportation in CuI layer. As a result, the TiO2 NW/Sb2S3/CuI-spray/Au device exhibits an overall power conversion efficiency of 1.18% under AM 1.5G simulated solar irradiation, which is about 2.88 times and 2.11 times higher than TiO2 NW/N719/CuI-spray/Au and TiO2 NW/Sb2S3/CuI-drop coating/Au devices, respectively. This study thus demonstrates the superiority of Sb2S3 sensitizer for TiO2 NW solar cells and spray technique for preparation of p-CuI hole conductor.
    New Journal of Chemistry 07/2015; DOI:10.1039/C5NJ00299K · 3.09 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Hierarchical heterostructures of p-type BiOCl nanosheets/n-type TiO2 nanofibers (p-BiOCl/n-TiO2 HHs) were prepared by combining the electrospinning technique and solvothermal method. BiOCl nanosheets with exposed {001} facets were densely and uniformly grown on the electrospun TiO2 nanofibers. The obtained p-BiOCl/n-TiO2 HHs exhibited enhanced UV-light photocatalytic activity due to the effects of p-n heterojunctions and high surface areas. Experiments proved that the generation rate of hydroxyl radicals for p-BiOCl/n-TiO2 HHs was much larger than that of TiO2 nanofibers. Moreover, the p-BiOCl/n-TiO2 HHs could be recycled easily by sedimentation because of their nanofibrous nonwoven web structure.
    Catalysis Communications 07/2015; 67. DOI:10.1016/j.catcom.2015.03.037 · 3.70 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Clarification of the energy-transfer (ET) mechanism is of vital importance for constructing efficient upconversion nanoplatforms for biological/biomedical applications. Yet, most strategies of optimizing these nanoplatforms were casually based on a dynamic ET assumption. In this work, we have modeled quantitatively the shell-thickness-dependent interplay between dynamic and static ET in nanosystems and validated the model in a typical biofunctional upconversion nanoplatform composed of NaYF4:Er, Yb/NaYF4 upconversion nanoparticles (UCNPs), and energy-acceptor photosensitizing molecule Rose Bengal (RB). It was determined that with a proper thickness shell, the energy transferred via dynamic ET as well as static ET in this case could be significantly improved by ∼4 and ∼9 fold, respectively, compared with the total energy transferred from bare core UCNPs. Our results shall form the bedrock in designing highly efficient ET-based biofunctional nanoplatforms.Keywords: NaYF4:Yb3+; Er3+/NaYF4; Förster resonant energy transfer; reabsorption; inner filter effect; quantitative analysis; optimal shell thickness; upconversion
    Journal of Physical Chemistry Letters 07/2015; 6(13):2518-2523. DOI:10.1021/acs.jpclett.5b00999 · 7.46 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this study, investigation of the unipolar resistive switching (RS) of InGaZnO film indicates that the reset voltage polarity can strongly affect the RS region. The dependence of the RS characteristics on the top electrode (Pt, Al, or Cu) was investigated. Asymmetrical electrodes (Cu/InGaZnO/Al) were chosen and the dependence of the RS parameters (e.g., high and low resistance states, set and reset voltages) on these two diverse electrodes can provide two indicators to trace the location of the RS region. The RS region is usually located near the anode when the applied set and reset voltages have the same polarity. In comparison, when the reset voltage has the opposite polarity to the set voltage, the RS region prefers to be located near the anode of the reset process rather than the cathode (which is used as the anode in the set process), indicating the movement of the RS region during the reset process. With the aid of joule heating, oxygen ions can overcome the energy barrier during the reset process under small voltage, resulting in the CFs restructuring and having the inverse shape, which is responsible for the drift mechanism of the RS region.
    Physica Status Solidi (A) Applications and Materials 07/2015; DOI:10.1002/pssa.201532235 · 1.62 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: It has long been known that efficient interfacial charge transfer between different phases of TiO2 is beneficial for enhanced photocatalysis. However, there has been considerable debate over the direction of charge transfer across the interface of different TiO2 phases. In this work, we study a case of TiO2 with novel anatase/TiO2(B) heterojunction (ABHJ), wherein charge carrier transfer across the heterojunction interface is intensively investigated. The ABHJ is prepared by a two-step alkaline hydrothermal route and features nanotubes with large surface area. Comprehensive analysis including UV-Vis-DR, XPS, Mott-Schottky measurement, EPR and transient photovoltage techniques provide evidence for a type II band alignment in ABHJ and migration of photogenerated electrons from anatase to TiO2(B), by which could effectively inhibit the recombination rate of photo-induced electrons-holes. Photocatalytic tests demonstrate that as-obtained ABHJ shows higher activity than both single phase and P25 for not only hydrogen production but also photodegradation of gaseous acetaldehyde, which is due to the synergistic effect between efficient charge separation at the interface and high surface area.
    Dalton Transactions 06/2015; 44(29). DOI:10.1039/C5DT01860A · 4.20 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Structural design of TiO2 photoanode is proved to be a useful approach in improving the energy conversion efficiency of dye-sensitized solar cells (DSSCs). Herein, bilayer TiO2 photoanode consisting of rutile nanowires (NWs) infiltrated with anatase nanoparticles (NPs) as bottom layer, and spherical voids (450nm) in NP film as top layer is prepared via a simple one-time spray technique on 1D TiO2 NW array. The bilayer structure exhibits excellent dye-loading property and efficient light scattering ability, as confirmed by dye-desorption, diffuse transmittance and reflectance spectra, and incident-photon-to-current conversion efficiency (IPCE) results. As a result, DSSC based on the bilayer photoanode ((1.6+2.6) μm) exhibits a remarkably 3.2 times and 3.5 times higher photocurrent output and overall energy conversion efficiency than 1D TiO2 NW device (1.6μm), under AM 1.5G simulated solar irradiation. The enhanced device performance can be ascribed to the synergistic effect of a large surface area for sufficient dye-loading, efficient light scattering for sufficient light harvesting, fast charge transport for efficient charge collection and highly porous structure of the spherical voids top layer for fast diffusion of I-/I3- electrolyte in the bilayer TiO2 photoanode. This study provides a facile route toward improving the photovoltaic performance of 1D TiO2 NW array solar cells based on constructing bilayer structure via a simple one-time spray technique.
    New Journal of Chemistry 06/2015; 39(6). DOI:10.1039/C5NJ00216H · 3.09 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Au nanoshells consisting of a dielectric core with a metallic layer of nanometer thickness exhibit tunable local surface plasmon resonance property. The core size has a great effect on the aggregation state of formed Au nanoshells, which leads to the variation of the intensity of surface enhanced Raman scattering (SERS). This paper reports a controllable aggregation for the fabrication of Au nanoshells with different size of core. TEM results demonstrated that formed Au nanoshells showed obvious aggregation with decreasing the size of core. By SERS analysis, different aggregation state leads to different SERS signal intensity. By comparison, Au nanoshells with core size of 50-80 nm exhibit high SERS enhancement effect.
    04/2015; 2(4):045004. DOI:10.1088/2053-1591/2/4/045004
  • [Show abstract] [Hide abstract]
    ABSTRACT: Bipolar resistive-switching (RS) memories were demonstrated based on an Ag/amorphous-carbon (a-C)/Pt sandwich structure. Here, the Ag-nanoclusters (NCs) were embedded into the a-C film via the sputtering deposition and thermal agglomeration. Versus the device without Ag-NCs, the embedding of the Ag-NCs in the a-C film favors the formation of incomplete Ag conducting filaments (CFs). This can act as tip electrodes for the RS. Therein, the local electric field can be enhanced and concentrated and lead to a simplified CF structure. Therefore, embedding Ag-NCs with a proper concentration into the electrolyte layer can effectively decrease the forming/switching voltages and improve the RS uniformity.
    Materials Letters 04/2015; 154. DOI:10.1016/j.matlet.2015.04.052 · 2.49 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Doping with impurities as well as introducing oxygen vacancies has been recognized as important means to enhance photocatalytic activity of TiO2 under visible-light irradiation. Here we report that simple ethanol impregnation followed with mild heat treatment (150-400oC) can render TiO2 nanoparticles colored and enhance visible-light photocatalytic activity of the material. The coloration and photocatalytic activity for β-naphthol and rhodamine B (RhB) degradation were observed to be dependent on heat-treatment temperature, and the highest activity as well as the most coloration was obtained at temperatures around 200 to 250oC. Comprehensive analyses based on X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) investigations as well as first-principle density functional calculation suggest that the simple ethanol impregnation treatment leads to the generation of oxygen vacancy on TiO2 surface which should be responsible for the coloration and enhanced photocatalytic activity.
    ACS Applied Materials & Interfaces 03/2015; 7(14). DOI:10.1021/acsami.5b00888 · 6.72 Impact Factor
  • Xin Xie · Meiling Zheng · Shencheng Fu · Xiuli Wang · Ye Li · Yichun Liu
    [Show abstract] [Hide abstract]
    ABSTRACT: Spirooxazine could be used as optical storage medium due to the excellent photochromic characteristic. In this paper, dynamics of holographic grating recording in spirooxazine-doped PMMA polymers was investigated using two coherent green beams (532 nm) and auxiliary blue-violet beam (405 nm) of various powers. The diffraction efficiency and growth rate of holographic gratings as well as the production rate of H-aggregation of merocyanine were strongly dependent on the auxiliary light power. In terms of these effects, an Aggregation Model was proposed, which was found to be in good agreement with the measurements. The corresponding dynamic parameters were obtained by fitting the experimental results, indicating that both the thermal rate constant and the aggregating rate constant increase exponentially versus the auxiliary light power. With the help of this model, the maximum brightness of reconstruction images was calculated and proved experimentally at the blue-violet light power of 57 mW. The results present a new approach to enhance the efficiency in spirooxazine-based films for holographic storage.
    Optics Communications 03/2015; 338. DOI:10.1016/j.optcom.2014.10.061 · 1.45 Impact Factor
  • Source
    Dataset: c3dt51958a
  • Lei Wang · Haiyang Xu · Yichun Liu · Linjiang Shen
    [Show abstract] [Hide abstract]
    ABSTRACT: A p-ZnO:N/n-GaN heterojuction light emitting diode was successfully constructed by thermal oxidation of Zn3N2 film which was deposited on n-type GaN substrates by N-plasma assisted pulsed laser deposition technology. The p-ZnO:N/n-GaN light emitting diode showed a typical diode current–voltage (I–V) characteristic and an electroluminescence emission of 517 nm was observed. This green electroluminescence emission came from the p-ZnO:N layer, which was confirmed by analyzing the results of x-ray diffraction, I–V measurement and electroluminescence spectra comprehensively.
    02/2015; 2(2):025901. DOI:10.1088/2053-1591/2/2/025901

Publication Stats

4k Citations
721.83 Total Impact Points


  • 2000–2015
    • Northeast Normal University
      • • Center for Advanced Optoelectronic Functional Materials Research
      • • Department of Chemistry
      Hsin-ching, Jilin Sheng, China
  • 2002–2006
    • Changchun Institute of Optics, Fine Mechanics and Physics
      Hsin-ching, Jilin Sheng, China
  • 2003
    • National Space Science
      Peping, Beijing, China
  • 2000–2003
    • Chinese Academy of Sciences
      • Graduate School
      Peping, Beijing, China