Desheng Liu

Shandong University, Chi-nan-shih, Shandong Sheng, China

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Publications (34)79.5 Total impact

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    ABSTRACT: A series of n-acene-graphene (n=3, 4, 5, 6) devices, in which n-acene molecules are sandwiched between two Zigzag graphene nanoribbon (ZGNR) electrodes, are modeled through the spin polarized density functional theory combined with non-equilibrium Green’s function technique. Our theoretical results show that with n-acene molecules ranging from anthracene to hexacene, the spin-polarized electronic states near the Fermi level can be induced by the spin-polarized ZGNR electrodes, which strengthen gradually to facilitate the electronic transport. A nearly 100% spin filtering ratio and a dual-orientation spin-rectifying effect are observed in a wide region of bias voltage. Importantly, an over 8000% giant magnetoresistance is obtained in the low bias range from -0.1V to +0.1V. Moreover, negative differential resistance behaviors are detected in these devices. The potential mechanisms for these intriguing phenomena are proposed and these findings would be instructive for the design and synthesis of high-performance graphene-based spin-related devices.
    Physical Chemistry Chemical Physics 03/2015; 17(17). DOI:10.1039/C5CP00544B · 4.20 Impact Factor
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    ABSTRACT: Nanostructured devices based on graphitic carbon nitrides bridging zigzag graphene nanoribbons.•Spin negative differential resistance properties related with the bias range.•High spin-filtering efficiency in the edge bridged device.
    Organic Electronics 12/2014; 15(12). DOI:10.1016/j.orgel.2014.10.016 · 3.68 Impact Factor
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    ABSTRACT: We have studied the electronic transport behaviors of dithienylethene-based polymer between two metal surfaces using nonequilibrium Green’s functions combined with density functional theory. The present computational results show that the polymer with closed and open configurations really demonstrates switching behavior which confirms the experimental observation. It is also found that the switching behavior depends on the electronic properties of two configurations of polymer instead of the contact modes. The on-off ratios of conductance between the closed and open configurations reach up to two orders of magnitude. Negative differential resistance and rectification phenomena are also observed in such systems.
    RSC Advances 08/2014; 4(77). DOI:10.1039/C4RA06904H · 3.71 Impact Factor
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    ABSTRACT: We model several Au/conjugated molecule/Au junctions in the presence of molecular geometrical torsions. A rectification ratio of around 10 in the twisty diphenyldipyrimidinyl system is obtained, which is in good agreement with experiment. Deeper insight into the rectification mechanism of the conjugated molecular diodes is presented on the basis of simulations in a set of simpler but similar junctions. The rectification effect (the ratio) is significantly improved with increasing the molecular twist, while the conductance is reduced accordingly. Our results suggest that the rectification can be enhanced by the geometrical-torsion-induced reduction in the conjugation length of organic molecules.
    Journal of Applied Physics 08/2014; 116(7):073701-073701-6. DOI:10.1063/1.4893365 · 2.19 Impact Factor
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    ABSTRACT: A series of ferrocenylalkanethiol (HSCnFc) single molecular junctions are modeled and their rectification ratios (RRs) are up to 100 (for HSC11Fc), which agrees with the experiments of Whitesides et al. Not only explanation to the origin of the remarkable large RR is given, but also the reason why one order deviation of RR between HSC11Fc and HSC9Fc is discussed and depicted, which was not pointed out by previous researchers. The single asymmetric accessible molecular orbital (MO) model is evaluated, which is different from the Donor (D)–Acceptor (A) models reported before and a clear negative differential resistance (NDR) behavior is found and explained in the HSC11Fc based device.
    Organic Electronics 02/2014; 15(2):484–490. DOI:10.1016/j.orgel.2013.11.039 · 3.68 Impact Factor
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    ABSTRACT: By applying the asymmetrical gate voltage on the 1,4-bis (fullero[c]pyrrolidin-1-yl) benzene BDC20 molecule, we investigate theoretically its electronic transport properties using the density functional theory and nonequilibrium Green's function formalism for a unimolecule device with metal electrodes. Interestingly, the rectifying characteristic with very high rectification ratio, 91.7 and 24.0, can be obtained when the gate voltage is asymmetrically applied on the BDC20 molecular device. The rectification direction can be tuned by the different gate voltage applying regions. The rectification behavior is understood in terms of the evolution of the transmission spectrum and projected density of states spectrum with applied bias combined with molecular projected self-consistent Hamiltonian states analyses. Our finding implies that to realize and greatly promote rectifying performance of the BDC20 molecule the variable gate voltage applying position might be a key issue.
    RSC Advances 01/2014; 4(32):16537. DOI:10.1039/c3ra47408a · 3.71 Impact Factor
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    ABSTRACT: Molecular devices with nitro groups display unique electronic transport properties in experiments. By applying the non-equilibrium Green's function combined with density functional theory, we find that the orientation of the nitro group with respect to the backbone of the molecule has a crucial effect on the device performance and can show unusual experimental phenomena. Furthermore, molecular devices with a nitro group are sensitive to gate voltage and suitable for making effective single molecular field-effect transistors. These results provide an important theoretical support to experiments and the design of future molecular devices by using nitro groups.
    Physical Chemistry Chemical Physics 11/2012; 15(3). DOI:10.1039/c2cp41480e · 4.20 Impact Factor
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    ABSTRACT: The electronic transport properties of a gated Au/(C20)2/Au molecular device are studied using nonequilibrium Green's function in combination with density functional theory. The results show that different applied positions of the external transverse gate voltage can effectively tune the current–voltage (I–V) characteristic of molecular devices. Rectifying behaviors of the device can be realized when the gate voltage is applied asymmetrically on the left C20 molecule, and the rectification directions can also be modulated by the positive or negative value of the gate voltage. These results provide an important theoretical support to experiments and the design of a molecular rectifier.
    RSC Advances 10/2012; 2(30):11349-11353. DOI:10.1039/C2RA21146G · 3.71 Impact Factor
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    ABSTRACT: By applying non-equilibrium Green’s functions (NEGF) in combination with the density functional theory (DFT), we investigate the electronic transport properties of molecular junctions constructed by OPE derivatives with different side groups combined C60 molecules. The results show that the side groups play an important role in the properties of electron transport. Negative differential resistance (NDR) is observed in such devices. Especially for the molecule with electron-donating group (−OCH3), two NDR appear at different bias voltage regions. And the mechanism is proposed for the NDR behavior, owing to the shift of the molecular orbitals caused by the change in molecule charge.
    Science China: Physics, Mechanics and Astronomy 08/2012; 55(8). DOI:10.1007/s11433-012-4768-8 · 0.86 Impact Factor
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    Peng Zhao, DeSheng Liu
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    ABSTRACT: By applying non-equilibrium Green’s function in combination with density functional theory, we investigated the electronic transport properties of capped-carbon-nanotube-based molecular junctions with multiple N and B dopants. The results show that the electronic transport properties are strongly dependent on the numbers and positions of N and B dopants. Best rectifying behavior is observed in the case with one N and one B dopants, and it is deteriorated strongly with the increasing dopants. The rectifying direction is even reversed with the change of doping positions. Moreover, obvious negative differential resistance behavior at very low bias is observed in some doping cases.
    Chinese Science Bulletin 06/2012; 57(17). DOI:10.1007/s11434-012-5148-5 · 1.37 Impact Factor
  • Kun Gao, Shijie Xie, Sun Yin, Desheng Liu
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    ABSTRACT: By applying a femtosecond electric pump pulse to a polymer, biexcitons are obtained and the relation between its yield and the photoexciting process is also presented. The simulations are performed within the framework of an extended version of one-dimensional Su–Schrieffer–Heeger tight-binding model combined with a nonadiabatic evolution method. In the discussions, effects of both the photoexciting energy and intensity are considered. The main result is that the yield ratio of biexcitons and excitons increases rapidly with the photoexciting intensity, and there exists a critical photoexciting intensity, beyond which the yield efficiency of biexcitons is even higher than that of excitons. The result theoretically verifies that, by increasing the photoexciting intensity, we can obtain biexcitons efficiently, which is consistent with the experimental speculation.
    Organic Electronics 05/2012; 13(5):784–788. DOI:10.1016/j.orgel.2012.02.005 · 3.68 Impact Factor
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    Peng Zhao, DeSheng Liu, Wei Liang
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    ABSTRACT: We investigate using the Landauer formalism, which combines both the non-equilibrium Green’s function and density functional theory, the effects of separation and orientation between two electrodes of boron-doped capped-carbon-nanotube-based molecular junctions on negative differential resistance. The results show that this negative differential resistance behavior is strongly dependent on the separation and orientation between the two electrodes. A gap width of 0.35 nm and maximal symmetry achieves the best negative differential resistance behavior.
    Chinese Science Bulletin 03/2012; 57(9). DOI:10.1007/s11434-012-4972-y · 1.37 Impact Factor
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    ABSTRACT: Using first-principles calculations, we study the electronic transport properties in Au(C20)2Au molecular junctions with different contact interface configurations: point contact and bond contact. We observe that the transmission through the bond contact is considerably higher than that of point contact. Furthermore, the I–V characteristics are rather different. For the bond contact, we get a metallic behavior followed by a varistor-type behavior. While as for the point contact, the current increases very slowly in a nonlinear way and is one order of magnitude smaller than that of bond contact. We attribute these obvious differences to the distinct contact configurations.
    Physics Letters A 01/2012; 376(5):773–778. DOI:10.1016/j.physleta.2011.12.025 · 1.63 Impact Factor
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    ABSTRACT: By using nonequilibrium Green’s function in combination with density functional theory, we study the electronic transport properties of two typical π-conjugated molecules (dithiol-benzene and C4S2), sandwiched between two metallic electrodes made of different metals. The presence of two different electrodes leads to Fano resonances at certain energy. As a consequence, electronic transport in future molecular electric circuits can be substantially affected when the molecular devices placed between electrodes with different chemical potentials. The Fano line shapes reveal that there is nonresonant channel when two asymmetric electrodes are employed.
    Applied Physics Letters 01/2012; 5(1). DOI:10.1063/1.3676190 · 3.52 Impact Factor
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    ABSTRACT: The electronic transport properties of an all-carbon mechanically controlled molecular device based on carbon nanotubes are studied using non-equilibrium Green's function in combination with density functional theory. A segment of (10,0) single-walled carbon nanutube (SWCNT) is placed concentrically outside a (5,0) SWCNT, namely, a (5,0)@(10,0) double-walled carbon nanotube (DWCNT). It is found that the position, orientation and length scaling of the (10,0) SWCNT have crucial effects on the electronic transport properties of the system. When the (10,0) SWCNT is mechanically pushed forward along the axial direction, alternation of on/off switching behavior under low bias and negative differential resistance behavior under high bias are observed. Significant changes in the electronic transport properties arise when rotating the (10,0) SWCNT around the common axis or adding carbon atom layers in the transport direction. Theoretical explanations are proposed for these phenomena.
    Physical Chemistry Chemical Physics 11/2011; 14(2):668-74. DOI:10.1039/c1cp22882j · 4.20 Impact Factor
  • Peng Zhao, Desheng Liu
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    ABSTRACT: Using first-principles density functional theory and the non-equilibrium Green’s function formalism, we have studied the electronic transport properties of the dumbbell-like fullerene dimer C131-based molecular junction. Our results show that the current–voltage curve displays an obvious negative differential resistance phenomenon in a certain bias voltage range. The negative differential resistance behavior can be understood in terms of the evolution of the transmission spectrum and the projected density of states with applied bias voltage. The present findings could be helpful for the application of the C131 molecule in the field of single molecular devices or nanometer electronics.
    Solid State Communications 10/2011; 151(20):1424-1427. DOI:10.1016/j.ssc.2011.07.007 · 1.70 Impact Factor
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    ABSTRACT: We report first-principles calculations of the current-voltage characteristic and the conductance of carbon-based molecular wires with different length capped with sulfur ends between two metallic electrodes made of different metals. The optimized molecular structure of carbon chain in the junction is presented on the structure of polyyne. The conductance of the polyyne wires shows oscillatory behavior depending on the number of carbon atoms (triple bonds). Current rectification is found and rectification direction presents inversion with the odd and even number of carbon atoms.
    Physics Letters A 09/2011; 375(41):3618–3623. DOI:10.1016/j.physleta.2011.08.032 · 1.63 Impact Factor
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    ABSTRACT: The electronic transport properties of a gated single 1,3-benzenedithiol molecular device are studied by using nonequilibrium Green's function in combination with density functional theory, which is hoped to complement the experiments. The results show that the external transverse gate electrodes can effectively tune the electronic transport properties of the molecular devices. Negative differential resistance behaviors are observed almost at the same source-drain bias when applied different gate voltages. Mechanisms are proposed for these phenomena. Designs of using one gated molecular device to realize five basic logic gates are also put forward.
    Applied Physics Letters 08/2011; 99(4-99):043304 - 043304-3. DOI:10.1063/1.3615691 · 3.52 Impact Factor
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    ABSTRACT: By applying nonequilibrium Green’s function formalism combined with the first-principles density functional theory, we investigate the electronic transport in two molecular junctions constituted by a substituted oligo (phenylene ehtynylene) sandwiched between two Au electrodes. Our calculations show that the weak molecule-electrode coupling is responsible for the observation of the negative differential resistance (NDR) effect in experiments. When the coupling is weak, the projected density of states (PDOS) of the molecule and the electrodes undergoes a mismatch-match-mismatch procedure, which increases and then decreases the transmission peak intensities, leading to a NDR effect. We also find that the localization/delocalization of the molecular orbitals and the change of charge state of the molecule have no direct relation with the NDR effect, because they change little as the voltage increases. Keywordsnegative differential resistance–substituted oligo (phenylene ehtynylene)–molecular junction–density functional theory–nonequilibrium Green’s function formalism
    Science China: Physics, Mechanics and Astronomy 08/2011; 54(8):1455-1460. DOI:10.1007/s11433-011-4406-x · 0.86 Impact Factor
  • Kun Gao, Shijie Xie, Sun Yin, Desheng Liu
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    ABSTRACT: Charge-transfer (CT) state in a donor–acceptor polymer heterojunction is theoretically investigated. The simulations are performed within the framework of an extended version of the one-dimensional Su–Schrieffer–Heeger tight-binding model combined with a nonadiabatic evolution method. We firstly focus on the formation and stability of a CT state in a static picture, in which case the effect of the energy offset is mainly concerned. Subsequently, dynamic process for the CT state formation and recombination is addressed. It is found that there exists a critical energy offset for the charge transfer and recombination, which is determined by both the exciton binding energy and the CT state one. The investigation may give a light to the optoelectronic and magnetic applications for organic polymers.
    Organic Electronics 06/2011; 12(6):1010-1016. DOI:10.1016/j.orgel.2011.03.024 · 3.68 Impact Factor