Yichun Liu

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

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Publications (253)797.12 Total impact

  • He Gou · Guorui Wang · Yanhong Tong · Qingxin Tang · Yichun Liu
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    ABSTRACT: ZnPc single-crystal nanobelts were grown by a physical vapor transport process with the length ranging from 20 to 150 μm and the width ranging from several tens of nanometers to several micrometers. Based on high crystalline ZnPc nanobelts, its single-crystal nanobelt transistors were realized. The field-effect mobility is as high as 0.75 cm2V-1s-1 with OTS modified SiO2 as dielectric, which is the highest value for the reported ZnPc devices. In addition, ZnPc nanobelt transistors show the excellently photosensitive properties with the high photoswitching ratio (|Ilight/Idark|) of 7.34 × 103 and the high photoresponsivity at 1.57 × 104 AW-1. These results indicate the future potential of ZnPc single-crystal transistors in organic electronic and optoelectronic applications.
    No preview · Article · Mar 2016 · Organic Electronics
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    ABSTRACT: Multi-heterojunction is more promising than single-heterojunction in photocatalysis due to the availability of more interfaces between each component. However, its photocatalytic activity is highly dependent on the contact mode of individual component. In this work, we assemble TiO2-WO3-Pt multi-heterojunction microspheres by ultrasonic spray pyrolysis and focus on their contact mode governed photocatalytic activity. The results reveal that highly crystalline WO3 nanosheets as building blocks could particularly enhance the photocatalytic activity of TiO2/WO3 system toward degrading gaseous acetaldehyde and isopropyl alcohol. Furthermore, loading of Pt nanoparticles on WO3 nanosheets could facilitate to a more prominent enhancement of activity than that of TiO2/Pt, benefiting from the two-electron reduction of oxygen at the interface of WO3/Pt. Meanwhile, high crystallinity of WO3 nanosheets allows a loading amount of Pt as low as 0.04 wt% in TiO2-WO3-Pt system, which reduces the catalyst cost in comparison with the conventional amount of 1wt%.
    No preview · Article · Feb 2016 · New Journal of Chemistry
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    Kexin Wang · Changlu Shao · Xinghua Li · Fujun Miao · Na Lu · Yichun Liu

    Preview · Article · Jan 2016 · Materials
  • Fujun Miao · Changlu Shao · Xinghua Li · Kexin Wang · Na Lu · Yichun Liu
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    ABSTRACT: Design and synthesis of hierarchical carbon hybrids based pseudocapacitive electrodes is next step forward for achieving high-performance supercapacitors. Here, the freestanding electrospun carbon nanofibers/carbon nanotubes/polyaniline (CNFs/CNTs/PANI) ternary composites have been fabricated successfully. Importantly, the hierarchical carbon hybrids by dense CNTs forests decorated CNFs serving as supports are crucial for the ternary composites to achieve high electrochemical properties. The hierarchical CNFs/CNTs hybrids serving as inner current collectors can afford plentiful transport channels for more rapidly transporting and collecting electrons, greatly reduce the ion diffusion length, and increase the utilization of pseudocapacitive materials. As expected, the ternary composites as electrodes present high specific capacitance (i.e., 315 F/g at 1 A/g) and dramatic rate capability (i.e., 235 F/g at 32 A/g) in three-electrode configuration. Moreover, the as-fabricated flexible solid-state supercapacitor based on the ternary composites also achieves desired electrochemical properties with high capacitance, high-rate capability, high energy/power density (i.e., 5.1 Wh/kg at 10.1 kW/kg) and remarkable cycling stability (i.e., 92% capacitance retention after 10,000 cycles at 2 A/g). These extraordinary electrochemical properties can be attributed to the well-designed structural advantages and synergistic effects.
    No preview · Article · Jan 2016 · ACS Sustainable Chemistry & Engineering
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    ABSTRACT: We demonstrate a forming-free electrochemical metallization resistive memory device (Ag/TiOxNy/Pt) based on the nanoporous titanium oxynitride (TiOxNy) thin film. Due to the nanoporous structure of TiOxNy, Ag atoms can migrate into the film during the Ag electrode evaporation process, resulting in a pre-formed Ag conductive filament inside the switching layer. This is responsible for the forming-free resistive switching behavior. Subsequently, resistive switching with attractive performance is achieved after a reset process, including good endurance, low operation voltages, and fast switching speed. The forming-free and reliable switching characteristics suggest that nanoporous TiOxNy thin film is one of the promising material candidates for future nonvolatile memory applications.
    No preview · Article · Jan 2016 · Journal of Alloys and Compounds
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    ABSTRACT: Freestanding electrodes with high capacitive performances are designed and constructed for flexible solid-state supercapacitors. Self-supporting electrospun CNFs (carbon nanofibers) networks with high surface areas and good conductivities were used as both internal current collectors and supports for pseudocapacitive materials. Repetitive in situ chemical polymerization of aniline monomers was adopted to deposit PANI (polyaniline) nanoflakes on CNFs continuously, with the advantages of good uniformity and controllable mass loading of PANI on CNFs. The specific capacitances of the as-synthesized series of CNFs/PANI composites based electrodes increased dramatically from 257 to 407 F/g accompanying with the increased mass loading of PANI from 32 to 78 wt.%. Moreover, two pieces of the obtained freestanding CNFs/PANI composite electrodes were also assembled into a solid-state supercapacitor by using polyvinyl alcohol/H2SO4 gel as electrolyte. The as-fabricated device presented excellent electrochemical performance with a specific capacitance of 201 F/g, an energy density of 4.5 Wh/kg at the power density of 103 W/kg, 80% capacitance retention after 6000 cycles, low leakage current and self-discharge characteristics and good flexibility. The flexible solid-state supercapacitors based on the freestanding CNFs/PANI composites might have potential applications in portable and flexible electronics.
    Full-text · Article · Jan 2016 · Energy
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    ABSTRACT: The morphology of TiO2 one-dimensional structures played an important role in improving the photovoltaic performance of nanostructural solar cells. Herein we utilized a low-temperature solution-deposited rutile layer to adjust the morphology of TiO2 nanorod (NR) arrays on SnO2:F (FTO) conductive glass. The higher concentration of TiCl4 precursor solution for the deposition of seed layer can generate more nucleation sites for the growth of TiO2 NRs, which raises the density of the TiO2 NR arrays and further restrains the growth of TiO2 at transverse direction. The obtained TiO2 NR arrays were successfully incorporated into dye-sensitized solar cells (DSSCs) as the photoanodes. The denser TiO2 NR arrays, resulted from the TiCl4 precursor solution with higher concentration, provided larger surface for the adsorption of dyes, and thus improved the light harvesting of solar cells. More importantly, the seed layers were proved to present effective blocking effect in preventing the electron recombination at FTO/electrolyte interface, which increased open-circuit voltage of DSSCs of ~110 mV. It is a convenient method to control the morphology of TiO2 NR photoanode and back electron reaction via seed layers, which could be used in other nanostructural photoelectrochemical devices.
    Full-text · Article · Jan 2016 · RSC Advances
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    ABSTRACT: Localized surface plasmon (LSP)-enhanced ultraviolet LEDs have been constructed via spin-coating Ag nanoparticles onto ZnO/SiO2 core/shell nanorod array/p-GaN heterostructures. Different from the previous reports where the dielectric spacer-layer thickness was determined only through photoluminescence (PL) characterization, the SiO2 shell thickness in this work is also optimized by actual electroluminescence (EL) measurements to maximize the enhancement. It is interesting to find that the enhancement ratios derived from PL and EL measurements demonstrate different thickness dependences on SiO2 shell: an optimal 3.5-fold PL enhancement was obtained at the SiO2 thickness of 16 nm, while an "abnormal" 7-fold EL enhancement was achieved at the thickness of 12 nm. Time-resolved spectroscopy studies, as well as theoretical estimations and numerical simulations, reveal that the higher-ratio EL enhancement stems from joint contributions, both internal-quantum-efficiency improvement induced by exciton-LSP coupling and light-extraction-efficiency improvement aroused by photon-LSP coupling.
    No preview · Article · Jan 2016 · ACS Applied Materials & Interfaces
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    ABSTRACT: We present a facile method to obtain MoS2-based nonvolatile memory field-effect transistors by oxygen plasma treatment on the MoS2 surface that is in contact with a dielectric. The oxygen plasma treatment provides a way of introducing deep defects into the MoS2 surface. Only those deep defects located at the semiconductor/dielectric interface can behave as charge trapping sites to develop the memory capability. No memory properties can be observed when the MoS2 surface far from the conductive channel was treated with oxygen plasma. This method brings promising advantages to MoS2-based memory devices obtained using a simple fabrication method and small device dimensions.
    No preview · Article · Jan 2016 · Applied Physics Express

  • No preview · Article · Jan 2016 · IEEE Transactions on Electron Devices
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    Full-text · Dataset · Dec 2015
  • Xi Chen · Yanhong Tong · Guorui Wang · Qingxin Tang · Yichun Liu
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    ABSTRACT: The transport properties and mechanism of the three-terminal field-effect nanowire cross junction have been systematically investigated. An interesting phenomenon, such as applied voltage bias on nanowire cross junction makes the ON/OFF current ratio of the transistor improved by over 2 orders of magnitude, has been observed. Different from the two-terminal nanowire cross junctions, the cross junction induced potential barrier in three-terminal counterparts is found to be capable to prevent the current of the top semiconductor nanowire from injecting into the bottom nanowire at off state, while to make the current of the top semiconductor nanowire contribute to the current of the bottom nanowire at on state, resulting in the current switch between on state and off state by the gate voltage modulation. (C) 2015 AIP Publishing LLC.
    No preview · Article · Dec 2015 · Applied Physics Letters
  • Xiaoli Zhao · Yanhong Tong · Qingxin Tang · Yichun Liu
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    ABSTRACT: D conformal organic single-crystal transistors and circuits based on a new type of elastic and flexible electrode are reported by Qingxin Tang, Yichun Liu, and co-workers in article number 1500239. The fabrication strategy makes the use of organic single crystals for conformal electronics possible. The cover image shows examples of these new electrodes, which are extremely light, adhered onto soap bubbles.
    No preview · Article · Dec 2015
  • Xiaoli Zhao · Yanhong Tong · Qingxin Tang · Yichun Liu

    No preview · Article · Nov 2015
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    ABSTRACT: The coexistence of uniform bipolar and unipolar resistive-switching (RS) characteristics was demonstrated in a double-layer AggnS-Ag/CuAlO2/Pt memory device. By changing the compliance current (CC) from 1 mA to 10 mA, the RS behavior can be converted from the bipolar mode (BRS) to the unipolar mode (URS). The temperature dependence of low resistance states further indicates that the CFs are composed of the Ag atoms and Cu vacancies for the BRS mode and URS mode, respectively. For this double-layer structure device, the thicker conducting filaments (CFs) will be formed in the ZnS-Ag layer, and it can act as tip electrodes. Thus, the formation and rupture of these two different CFs are located in the CuAlO2 layer, realizing the uniform and stable BRS and URS.
    No preview · Article · Nov 2015 · Applied Surface Science
  • Sisi Cui · Bing Yao · Xue Sun · Junli Hu · Yifa Zhou · Yichun Liu
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    ABSTRACT: Nanofibers of natural polymers represent an essential class of materials in biomedicine. Pectin is a plant-sourced anionic polysaccharide widely used in food products and biomedicine owning to its abundance, biocompatibility and inherent bioactivity. However, current electrospun pectin nanofibers are suffered from high content of carrier polymer, which may lead to low integrity and mechanical strength as well as in vivo toxicity. We report here a strategy to reduce the content of carrier polymer, polyethylene oxide (PEO) in our study, in pectin nanofibers, via electrospinning at low loading followed with selective washing. With improved electrospinning condition, we first enabled electrospinning of pectin nanofibers at low PEO loading. Then the PEO was removed by washing with a selective solvent to give pectin nanofibers containing only 1.5% PEO. The strategy was versatile to pectins from various sources and of various degree of esterification. The pectin nanofibers exhibited Young's modulus as high as 358.5MPa. In view of their rich bioactivity, the pectin nanofibers of low content of carrier polymer are promising materials for a wide range of biomedical applications.
    No preview · Article · Oct 2015
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    ABSTRACT: The electron transport layer (ETL) plays an important role in planar heterojunction perovskite solar cell (PSCs), by affecting the light-harvesting, electron injection and transportation processes, and especially the crystallization of perovskite absorber. In this work, we utilized a commercial TKD-TiO2 nanoparticle with a small diameter of 6 nm for the first time to prepare a compact ETL by spin coating. The packing of small-size particles endowed TKD-TiO2 ETL an appropriate surface-wettability, which is beneficial to the crystallization of perovskite deposited via solution-processed method. The uniform and high-transmittance TKD-TiO2 films were successfully incorporated into PSCs as ETLs. Further careful optimization of ETL thickness gave birth to a highest power conversion efficiency of 11.0%, which was much higher than that of PSC using an ETL with the same thickness made by spray pyrolysis. This TKD-TiO2 provided a universal solar material suitable for the further large-scale production of PSCs. The excellent morphology and the convenient preparation method of TKD-TiO2 film gave it an extensive application in photovoltaic devices.
    No preview · Article · Oct 2015 · Journal of Energy Chemistry
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    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.
    No preview · Article · Sep 2015 · Carbon
  • Manshu Han · Jiangang Ma · Haiyang Xu · Yichun Liu
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    ABSTRACT: In this paper, single crystalline Bi2Se3 nanostructures including nanowires, nanoribbons, nanoplates and bridge-like nanostructures have been grown by physical vapor deposition. By investigating the morphological evolution of the Bi2Se3 nanostructures, we found that Bi2Se3 nanoribbons with the long axis along <112 @#x0305;0> could facilitate the formation of bridge-like nanostructures. Subsequently, a two-step growth process had been developed to increase both the size and the amount of the bridge-like Bi2Se3 nanostructures effectively, which shows great promise to realize the growth of large-size two dimensional materials for various optoelectronic and spintronic applications.
    No preview · Article · Sep 2015 · CrystEngComm
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    ABSTRACT: A simple top electrode preparation process, employing continuous graphene oxide films as electrode supporting layers, was adopted to fabricate a ZnO nanorod array/p-GaN heterojunction LED. The achieved LED demonstrated different electroluminescence behaviors under forward and reverse biases: a yellow-red emission band was observed under forward bias, whereas a blue-UV emission peak was obtained under reverse bias. Electroluminescence spectra under different currents and temperatures, as well as heterojunction energy-band alignments, reveal that the yellowred emission under forward bias originates from recombinations related to heterointerface defects, whereas the blue-UV electroluminescence under reverse bias is ascribed to transitions from near-band-edge and Mg-acceptor levels in p-GaN.
    No preview · Article · Sep 2015 · Applied Physics Express

Publication Stats

5k Citations
797.12 Total Impact Points

Institutions

  • 2000-2016
    • Northeast Normal University
      • • Center for Advanced Optoelectronic Functional Materials Research
      • • Department of Chemistry
      Hsin-ching, Jilin Sheng, China
  • 2015
    • Changchun Normal University
      Hsin-ching, Jilin Sheng, China
  • 2003-2006
    • Changchun Institute of Optics, Fine Mechanics and Physics
      Hsin-ching, Jilin Sheng, China
    • National Space Science
      Peping, Beijing, China
  • 2000-2003
    • Chinese Academy of Sciences
      • Graduate School
      Peping, Beijing, China