A thioester-functionalized triphenylamine hole-transporting molecule (TPD-SAc) was synthesized and self-assembled to form a monolayer on an ultra-thin Au film supported on indium-tin oxide glass. The modified surfac...A thioester-functionalized triphenylamine hole-transporting molecule (TPD-SAc) was synthesized and self-assembled to form a monolayer on an ultra-thin Au film supported on indium-tin oxide glass. The modified surface was characterized by aqueous contact angle, ellipsometer, atomic force microscopy, X-ray photoelectron spectroscopy, and ultraviolet pho- toelectron spectrometer to substantiate the formation of compact and pinhole-free monolayers. The modified organic light emitting diode device [indium-tin oxide/Au (5 nm)/self-assembled monolayers (SAM)/TPD (50 nm)/Alq3 (40 nm)/TPBI (15 nm)/LiF (1 nm)/A1 (100 nm)] showed a luminance of 7303.90 cd/m^2 and a current efficiency of 8.49 cd/A with 1.78 and 2.29-fold increase, respectively, compared to the control device without SAM. The improvements were attributed to the enhanced compatibility of the organic-inorganic interface, matched energy level by introduction of an energy mediating step and superior hole-injection property of SAM molecules.展开更多
The recently discovered(Li_(1-x) Fe_x)OHFe Se superconductor with T c about 40 K provides a good platform for investigating the magnetization and electrical transport properties of Fe Se-based superconductors. By usin...The recently discovered(Li_(1-x) Fe_x)OHFe Se superconductor with T c about 40 K provides a good platform for investigating the magnetization and electrical transport properties of Fe Se-based superconductors. By using a hydrothermal ion-exchange method,we have successfully grown crystals of(Li_(1-x) Fe_x)OHFe Se. X-ray diffraction on the sample shows the single crystalline Pb O-type structure with the c-axis preferential orientation. Magnetic susceptibility and resistive measurements show an onset superconducting transition at around T c=38.3 K. Using the magnetization hysteresis loops and Bean critical state model, a large critical current J s is observed in low temperature region. The critical current density is suppressed exponentially with increasing magnetic field.Temperature dependencies of resistivity under various currents and fields are measured, revealing a robust superconducting current density and bulk superconductivity.展开更多
The thermal phonon transport is a key matter for heat managing in materials science which is crucial for device miniaturization and power density increase. Herein, we report the synthesis, structure and characterizati...The thermal phonon transport is a key matter for heat managing in materials science which is crucial for device miniaturization and power density increase. Herein, we report the synthesis, structure and characterization of a new compound, Cs2Ge3Ga6Se14, with a unique anisotropic structure simultaneously containing Ge^3+ and Ge^2+ that adopt(Ge1)2^3+ Se6 dimer or(Ge2)^2+Se6 octahedron, respectively. The thermal conductivity was measured to be 0.57–0.48 W m^-1 K^-1 from 323 to 773 K, the lowest value among all the known Ge-containing compounds, approaching its glass limit according to the Cahill’s formulation. More importantly, we discover for the first time that the vibration uncoupling of Ge with different valence states hinders the effective thermal energy transport between the(Ge1)2^3+ Se6 dimer and(Ge2)^2+Se6 octahedron, and consequently lowers the thermal conductivity. In addition, we propose a structure factor f = sin(180) ×d/l(i =A, B)iGe Qi, with which a structure map of the Cs2 Ge3 M6 Q14 family is given.展开更多
We investigate theoretically single photon transport properties in coupled-resonator waveguide coupling with a nanocavity interacting with an external mirror. By using the discrete coordinates approach, transmission a...We investigate theoretically single photon transport properties in coupled-resonator waveguide coupling with a nanocavity interacting with an external mirror. By using the discrete coordinates approach, transmission and reflection amplitudes of the propagating single photon in the waveguide are obtained. The influence of the coupling strength between the nanocavity and the external mirror on the single photon scattering spectra is discussed. We also extend the results to the waveguide with linear and quadratic form dispersion relations.展开更多
We investigated the electronic energy band and transport features of graphene superlattice with periodically modulated magnetic vector potential and electrostatic potential. It is found that both parallel magnetic vec...We investigated the electronic energy band and transport features of graphene superlattice with periodically modulated magnetic vector potential and electrostatic potential. It is found that both parallel magnetic vector potential and electrostatic potential can decisively shift Dirac point in a different way, which may be an efficient way to achieve electron or hole filter. We a/so find that applying modulated parallel and anti-parallel magnetic vector potential to the electrons can efficiently change electronic states between pass and stop states, which can be useful in designing electron or hole switches and lead to large magneto-resistance.展开更多
Using self-flux method,we have successfully grown the parent phase of the single crystals of CaFeAsF1-x.The X-ray di?raction indicates good crystallinity.In-plane resistivity shows a bad metallic behavior with a sharp...Using self-flux method,we have successfully grown the parent phase of the single crystals of CaFeAsF1-x.The X-ray di?raction indicates good crystallinity.In-plane resistivity shows a bad metallic behavior with a sharp drop of resistivity at about T SDW=119K.This anomaly is associated with the possible spin density wave(SDW)order.Interestingly near T SDW,the resistivity exhibits a cusp-like feature,which may be understood as the strong coupling effect between the electrons and the antiferromagnetic(AF)spin fluctuations.A reduction of fluorine or application of a high pressure will suppress the SDW feature and induce superconductivity.Hall effect measurements reveal a positive Hall coefficient below T SDW indicating a dominant role of the hole-like charge carriers in the parent phase.Strong magnetoresistance has been observed below T SDW suggesting multiple conduction channels of the charge carriers.展开更多
基金supported by the National Natural Science Foundation of China(Nos.21506151,21576195 and 21776207)
文摘A thioester-functionalized triphenylamine hole-transporting molecule (TPD-SAc) was synthesized and self-assembled to form a monolayer on an ultra-thin Au film supported on indium-tin oxide glass. The modified surface was characterized by aqueous contact angle, ellipsometer, atomic force microscopy, X-ray photoelectron spectroscopy, and ultraviolet pho- toelectron spectrometer to substantiate the formation of compact and pinhole-free monolayers. The modified organic light emitting diode device [indium-tin oxide/Au (5 nm)/self-assembled monolayers (SAM)/TPD (50 nm)/Alq3 (40 nm)/TPBI (15 nm)/LiF (1 nm)/A1 (100 nm)] showed a luminance of 7303.90 cd/m^2 and a current efficiency of 8.49 cd/A with 1.78 and 2.29-fold increase, respectively, compared to the control device without SAM. The improvements were attributed to the enhanced compatibility of the organic-inorganic interface, matched energy level by introduction of an energy mediating step and superior hole-injection property of SAM molecules.
基金supported by the National Natural Science Foundation of China(Grant No.11534005)the Ministry of Science and Technology of China(Grant Nos.2011CBA00102 and 2012CB821403)
文摘The recently discovered(Li_(1-x) Fe_x)OHFe Se superconductor with T c about 40 K provides a good platform for investigating the magnetization and electrical transport properties of Fe Se-based superconductors. By using a hydrothermal ion-exchange method,we have successfully grown crystals of(Li_(1-x) Fe_x)OHFe Se. X-ray diffraction on the sample shows the single crystalline Pb O-type structure with the c-axis preferential orientation. Magnetic susceptibility and resistive measurements show an onset superconducting transition at around T c=38.3 K. Using the magnetization hysteresis loops and Bean critical state model, a large critical current J s is observed in low temperature region. The critical current density is suppressed exponentially with increasing magnetic field.Temperature dependencies of resistivity under various currents and fields are measured, revealing a robust superconducting current density and bulk superconductivity.
基金supported by the National Natural Science Foundation of China (21975032 and 21571020)the National Key Research and Development Program of China (2018YFA0702100)
文摘The thermal phonon transport is a key matter for heat managing in materials science which is crucial for device miniaturization and power density increase. Herein, we report the synthesis, structure and characterization of a new compound, Cs2Ge3Ga6Se14, with a unique anisotropic structure simultaneously containing Ge^3+ and Ge^2+ that adopt(Ge1)2^3+ Se6 dimer or(Ge2)^2+Se6 octahedron, respectively. The thermal conductivity was measured to be 0.57–0.48 W m^-1 K^-1 from 323 to 773 K, the lowest value among all the known Ge-containing compounds, approaching its glass limit according to the Cahill’s formulation. More importantly, we discover for the first time that the vibration uncoupling of Ge with different valence states hinders the effective thermal energy transport between the(Ge1)2^3+ Se6 dimer and(Ge2)^2+Se6 octahedron, and consequently lowers the thermal conductivity. In addition, we propose a structure factor f = sin(180) ×d/l(i =A, B)iGe Qi, with which a structure map of the Cs2 Ge3 M6 Q14 family is given.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11105001 and 61472282the Anhui Provincial Natural Science Foundation under Grant Nos.1408085QA22,1608085MA09,and 1508085MF129
文摘We investigate theoretically single photon transport properties in coupled-resonator waveguide coupling with a nanocavity interacting with an external mirror. By using the discrete coordinates approach, transmission and reflection amplitudes of the propagating single photon in the waveguide are obtained. The influence of the coupling strength between the nanocavity and the external mirror on the single photon scattering spectra is discussed. We also extend the results to the waveguide with linear and quadratic form dispersion relations.
基金Supported by the Key Program of the National Natural Science Foundation of China under Grant No. 10832005
文摘We investigated the electronic energy band and transport features of graphene superlattice with periodically modulated magnetic vector potential and electrostatic potential. It is found that both parallel magnetic vector potential and electrostatic potential can decisively shift Dirac point in a different way, which may be an efficient way to achieve electron or hole filter. We a/so find that applying modulated parallel and anti-parallel magnetic vector potential to the electrons can efficiently change electronic states between pass and stop states, which can be useful in designing electron or hole switches and lead to large magneto-resistance.
基金supported by the National Basic Research Program of China(Grant Nos.2011CBA00102,2010CB923002 and 2012CB821403)the National Natural Science Foundation of China and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Using self-flux method,we have successfully grown the parent phase of the single crystals of CaFeAsF1-x.The X-ray di?raction indicates good crystallinity.In-plane resistivity shows a bad metallic behavior with a sharp drop of resistivity at about T SDW=119K.This anomaly is associated with the possible spin density wave(SDW)order.Interestingly near T SDW,the resistivity exhibits a cusp-like feature,which may be understood as the strong coupling effect between the electrons and the antiferromagnetic(AF)spin fluctuations.A reduction of fluorine or application of a high pressure will suppress the SDW feature and induce superconductivity.Hall effect measurements reveal a positive Hall coefficient below T SDW indicating a dominant role of the hole-like charge carriers in the parent phase.Strong magnetoresistance has been observed below T SDW suggesting multiple conduction channels of the charge carriers.