As typical quarternary copper-based chalcogenides,Cu–Zn–Sn–S nanocrystals(CZTS NCs)have emerged as a newfashioned electrocatalyst in hydrogen evolution reactions(HERs).Oleylamine(OM),a reducing surfactant and solve...As typical quarternary copper-based chalcogenides,Cu–Zn–Sn–S nanocrystals(CZTS NCs)have emerged as a newfashioned electrocatalyst in hydrogen evolution reactions(HERs).Oleylamine(OM),a reducing surfactant and solvent,plays a significant role in the assisting synthesis of CZTS NCs due to the ligand effect.Herein,we adopted a facile one-pot colloidal method for achieving the structure evolution of CZTS NCs from 2D nanosheets to 1D nanorods assisted through the continuous addition of OM.During the process,the mechanism of OM-induced morphology evolution was further discussed.When merely adding pure 1-dodecanethiol(DDT)as the solvent,the CZTS nanosheets were obtained.As OM was gradually added to the reaction,the CZTS NCs began to grow along the sides of the nanosheets and gradually shrink at the top,followed by the formation of stable nanorods.In acidic electrolytic conditions,the CZTS NCs with 1.0 OM addition display the optimal HER activity with a low overpotential of 561 m V at 10 m A/cm^(2) and a small Tafel slope of 157.6 m V/dec compared with other CZTS samples.The enhancement of HER activity could be attributed to the contribution of the synergistic effect of the diverse crystal facets to the reaction.展开更多
Different concentrations of Mg^(2+) -doped hexagonal phase NaGdF_4:Yb^(3+), Er^(3+)nanocrystals(NCs) were synthesized by a modified solvothermal method. Successful codoping of Mg^(2+)ions in upconversion nanoparticles...Different concentrations of Mg^(2+) -doped hexagonal phase NaGdF_4:Yb^(3+), Er^(3+)nanocrystals(NCs) were synthesized by a modified solvothermal method. Successful codoping of Mg^(2+)ions in upconversion nanoparticles(UCNPs) was supported by XRD, SEM, EDS, and PL analyses. The effects of Mg^(2+)doping on the morphology and the intensity of the upconversion(UC) emission were discussed in detail. It turned out that with the concentration of Mg^(2+)increasing, the morphology of the nanoparticles turn to change gradually and the UC emission was increasing gradually as well. Notably the UC fluorescence intensities of Er^(3+)were gradually improved owing to the codoped Mg^(2+)and then achieved a maximum level as the concentration of Mg^(2+)ions was 60 mol% from the amendment of the crystal structure of β-NaGdF_4:Yb^(3+),Er^(3+)nanoparticles. Moreover, the UC luminescence properties of the rare-earth(Yb3+, Er^(3+)) ions codoped NaGdF_4 nanocrystals were investigated in detail under 980-nm excitation.展开更多
The acceleration ability of electrons in SiO2 and ZnS was compared through the variation of emission intensity based on ZnS∶Er electroluminescence during the reverse of polarity of sinusoidal voltage. In order to avo...The acceleration ability of electrons in SiO2 and ZnS was compared through the variation of emission intensity based on ZnS∶Er electroluminescence during the reverse of polarity of sinusoidal voltage. In order to avoid the influence of work function of electrode, cathodal and anodal materials were ITO （indium tin oxide）. The ratio of maximum emission intensity under positive and negative half period is 2.18. This result demonstrates that the electron acceleration ability of SiO2 is 2.18 times stronger than that of ZnS.展开更多
Series devices of ITO/ZnO/ZnO nanorods/MEH-PPV/Al have been fabricated.ITO and ZnO nanorods of some devices are treated by O_(2) plasma.The electroluminescence of different devices is detected under different biases.U...Series devices of ITO/ZnO/ZnO nanorods/MEH-PPV/Al have been fabricated.ITO and ZnO nanorods of some devices are treated by O_(2) plasma.The electroluminescence of different devices is detected under different biases.UV electroluminescence of ZnO nanorods at 380 nm is observed in all the devices.The intensity of 380 nm increases when both ITO and ZnO nanorods are treated.The turn-on voltage of the treated device is lower than that of the non-treated device,and the EL power is enhanced.When the thickness of MEH-PPV is sufficiently thin,only 380 nm electroluminescence,besides a weak defect emission at 760 nm,is detected.The enhancement mechanism of the electroluminescence of the treated devices is discussed.展开更多
Nanosized long-persistent phosphors SrS:Eu2+, Dy3+ were prepared by the hydrothermal method.The samples were characterized by X-ray powder diffraction, transmission electron microscopy, and charge-coupled device spect...Nanosized long-persistent phosphors SrS:Eu2+, Dy3+ were prepared by the hydrothermal method.The samples were characterized by X-ray powder diffraction, transmission electron microscopy, and charge-coupled device spectrometry.The persistence characteristic was studied using the decay curves.The results showed that the emission intensity decreased sharply with temperature increasing, although the particle size increased.The S2-vacancies caused by oxidization served as shallow traps, and Dy3+ served as deep traps in SrS:Eu2+, Dy3+.The afterglow intensity of SrS:Eu2+, Dy3+ was higher than that of SrS:Eu2+ prepared at the same temperature.However, the minimization span of initial afterglow with temperature for the former sample was larger than that for the latter.Binary-doped phosphor decayed more slowly than the singly doped one.The afterglow of SrS:Eu2+, Dy3+ decayed more quickly with the increase of sintering temperature.展开更多
Sputtering method was used to prepare Ni-Mo alloy electrodes for hydrogen production in alkaline solution. The influences of the working pressure during deposition and the substrate temperature on the electrochemical ...Sputtering method was used to prepare Ni-Mo alloy electrodes for hydrogen production in alkaline solution. The influences of the working pressure during deposition and the substrate temperature on the electrochemical behavior of electrode were characterized by steady-state polarization plot and Tafel polarization curve measurements. And the physical properties of electrodes were characterized by XRD, SEM, AFM and EDS. It is found that the overpotential is significantly influenced by the working pressure which affects critically the electrode surface morphology, and two Tafel regions are observed for each sample. The overpotential value does not change very much with the substrate temperature. The XRD results indicates that the electrodes should be considered nanocrystalline. Thornton model for the microstructure of sputter-deposited electrodes is referred to explain the observed microstructure change.展开更多
In order to investigate the impedance matching properties of microwave absorbers,the ternary nanocomposites of GO/PANI/Fe_3O_4(GPF) are prepared via a two-step method,GO/PANI composites are synthesized by dilute polym...In order to investigate the impedance matching properties of microwave absorbers,the ternary nanocomposites of GO/PANI/Fe_3O_4(GPF) are prepared via a two-step method,GO/PANI composites are synthesized by dilute polymerization in the presence of aniline monomer and GO,and GO/PANI/Fe_3O_4 is prepared via a co-precipitation method.The obtained nanocomposites are characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),and Fourier transform infrared spectroscopy(FTIR),respectively.The microwave absorbability reveals enhanced microwave absorption properties compared with GO,PANI,and GO/PANI.The maximum reflection loss of GO/PANI/Fe_3O_4 is up to-27 dB at 14 GHz with its thickness being 2 mm,and its absorption bandwidths exceeding-10 dB are more than 11.2 GHz with its thickness values being in the range from 1.5 mm-4 mm.It provides that GO/PANI/Fe_3O_4 can be used as an attractive candidate for microwave absorbers.展开更多
N-dodecanethiol capped zinc sulfide(Zn S) nanocrystals were synthesized by the one-pot approach and blended with poly(N-vinylcarbazole)(PVK) to fabricate electrical bistable devices. The corresponding devices did exhi...N-dodecanethiol capped zinc sulfide(Zn S) nanocrystals were synthesized by the one-pot approach and blended with poly(N-vinylcarbazole)(PVK) to fabricate electrical bistable devices. The corresponding devices did exhibit electrical bistability and negative differential resistance(NDR) effects. A large ON/OFF current ratio of 104 at negative voltages was obtained by applying different amplitudes of sweeping voltage. The observed conductance switching and the negative differential resistance are attributed to the electric-field-induced charge transfer between the nanocrystals and the polymer,and the charge trapping/detrapping in the nanocrystals.展开更多
A novel rare earth complex Eu(TTA)2(N-HPA)Phen (TTA=thenoyltrifluoroacetone, N-HPA=N-phenylanthranilic acid, and phen=1,10-phenathroline), which contains three different ligands, was synthesized. The Eu complex was bl...A novel rare earth complex Eu(TTA)2(N-HPA)Phen (TTA=thenoyltrifluoroacetone, N-HPA=N-phenylanthranilic acid, and phen=1,10-phenathroline), which contains three different ligands, was synthesized. The Eu complex was blended with poly N-vinylcarbazole (PVK) in different weight ratios and spin coated into films. The luminescence properties of films were investigated and energy transfer between PVK and the complex was discussed. Multilayer structural devices consisting of ITO/PVK∶Eu(TTA)2(N-HPA)phen/BCP/Alq3/A1 were fabricated with PVK∶Eu(TTA)2(N-HPA) as light-emitting layer. Increasing the concentration of Eu in the PVK thin film would inhibit the emission of PVK to different degrees. Finally, the pure red luminescence of europium(Ⅲ) was observed when the doping weight ratio was approximately 1∶5, which indicated an effective energy transfer from PVK to rare earth complex.展开更多
We report on the fabrication and electrical characteristics of Ga-doped ZnO thin film transistors(TFTs).Low Ga-doped(0.7wt%)ZnO thin films were deposited on SiO_(2)/p−Si substrates by rf magnetron sputtering.The GZO T...We report on the fabrication and electrical characteristics of Ga-doped ZnO thin film transistors(TFTs).Low Ga-doped(0.7wt%)ZnO thin films were deposited on SiO_(2)/p−Si substrates by rf magnetron sputtering.The GZO TFTs show a mobility of 1.76 cm2/V⋅s,an on/off ratio of 1.0×10^(6),and a threshold voltage of 35 V.The time−dependent instability of the TFT is studied.The VTH shifts negatively.In addition,the device shows a decrease of the on/off ratio,mainly due to the increase of the off-current.The mechanisms of instability are discussed.展开更多
In this work, bathocuproine (BCP) and bathophenanthroline (Bphen), commonly used in small-molecule organic solar cells (OSCs), are adopted as the buffer layers to improve the performance of the polymer solar cells (PS...In this work, bathocuproine (BCP) and bathophenanthroline (Bphen), commonly used in small-molecule organic solar cells (OSCs), are adopted as the buffer layers to improve the performance of the polymer solar cells (PSCs) based on poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV): [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction. By inserting BCP or Bphen between the active layer and the top cathode, all the performance parameters are dramatically improved. The power conversion efficiency is increased by about 70% and 120% with 5-nm BCP and 12-nm Bphen layers, respectively, when compared with that of the devices without any buffer layer. The performance enhancement is attributed to BCP or Bphen (i) increasing the optical field, and hence the absorption in the active layer, (ii) effectively blocking the excitons generated in MEH-PPV from quenching at organic/aluminum (Al) interface due to the large band-gap of BCP or Bphen, which results in a significant reduction in series resistance (Rs), and (iii) preventing damage to the active layer during the metal deposition. Compared with the traditional device using LiF as the buffer layer, the BCP-based devices show a comparable efficiency, while the Bphen-based devices show a much larger efficiency. This is due to the higher electron mobility in Bphen than that in BCP, which facilitates the electron transport and extraction through the buffer layer to the cathode.展开更多
A series of Eu2+-doped fluorochlorozirconate glass-ceramics were prepared by solid state reaction method. X-ray diffraction, pho-toluminescence, photo-stimulated luminescence (PSL) and the turbidity of fluorozirconate...A series of Eu2+-doped fluorochlorozirconate glass-ceramics were prepared by solid state reaction method. X-ray diffraction, pho-toluminescence, photo-stimulated luminescence (PSL) and the turbidity of fluorozirconate glass containing BaCl2 nano- and micro-crystals were measured for the samples annealed at 290 °C for 10 min. The PSL was attributed to the characteristic emission of Eu2+ in nano-crystallites of BaCl2, which formed in the glass upon annealing. The PSL efficiency of the glass ceramic was increased by increasing the concentration of BaCl2, which, however, resulted in the decreasing in the transparency of the sample. The sample turned to a semi-transparent glass ceramic or even an opaque and milky white one from a near-transparent glass. The trade-off between optical trans-parency and PSL intensity over different concentrations of BaCl2 for X-ray imaging plate applications was briefly discussed.展开更多
Small molecule organic photovoltaics(SMPVs) were prepared by utilizing liquid crystalline donor material BTR-Cl and two similar optical bandgap non-fullerene acceptor materials BTP-BO-4 F and Y6.The BTPBO-4 F and Y6 h...Small molecule organic photovoltaics(SMPVs) were prepared by utilizing liquid crystalline donor material BTR-Cl and two similar optical bandgap non-fullerene acceptor materials BTP-BO-4 F and Y6.The BTPBO-4 F and Y6 have the similar optical bandgap and different absorption coefficients.The corresponding binary SMPVs exhibit different short circuit current density(/sc)(20.38 vs.23.24 mA cm^(-2)),and fill factor(FF)(70.77% vs.67.21%).A 14.46% power conversion efficiency(PCE) is acquired in ternary SMPVs with 30 wt% Y6,companied with a JSC of 24.17 mA cm^(-2) a FF of 68.78% and an open circuit voltage(Voc) of 0.87 V.The improvement on PCE of ternary SMPVs should originate from the well trade-off between phase separation and photon harvesting of ternary active layers by incorporating 30 wt% Y6 in acceptors.This work may deliver insight onto the improved performance of SMPVs by superposing the superiorities of binary SMPVs with similar optical bandgap acceptors into one ternary cell.展开更多
The rare earth ternary complex of Eu 3+ with thenoyltrifluoroacetone,and 4,7-2NH2 phenanthroline was synthesized and well characterized by UV,fluorescent,IR spectrometry and X-ray diffractometry(XRD)as well as element...The rare earth ternary complex of Eu 3+ with thenoyltrifluoroacetone,and 4,7-2NH2 phenanthroline was synthesized and well characterized by UV,fluorescent,IR spectrometry and X-ray diffractometry(XRD)as well as elemental analysis.The results show that the complex of Eu(III)emits strong red luminescence when excited by UV light,and Eu(TTA)3(2NH2-Phen)has the higher sensitized luminescent efficiency and longer lifetime than Eu(TTA)3(Phen).In device of ITO/PVK/Eu(TTA)3(2NH2-Phen)/Al,the spectra of Eu(TTA)3(2NH2-Phen)with different ratios for spin-cast film were monitored.The main emitting peak at 614 nm can be attributed to the transition of 5 D0→ 7 F2 of Eu 3+ and this process results in the enhancement of red emission from electroluminescence device.The effect and mechanism of the ligands on the luminescence properties of europium complex were discussed.The results show that the luminescence intensity of the title complexes greatly increases in comparison with that of their corresponding complexes,revealing that the second ligands form very good synergistic effect with the first ligands.The title complexes possess excellent thermal stability properties,and are hopefully developed into fine PL and EL red materials.展开更多
Molybdenum disulfide quantum dots(MoS_2QDs) were synthesized via a hydrothermal method using sodium molybdate and cysteine as molybdenum and sulfur sources, respectively. The optimal hydrothermal time was studied. Fur...Molybdenum disulfide quantum dots(MoS_2QDs) were synthesized via a hydrothermal method using sodium molybdate and cysteine as molybdenum and sulfur sources, respectively. The optimal hydrothermal time was studied. Furthermore, the as synthesized water-soluble MoS_2QDs were used as a fluorescence probe for the sensitive and selective detection of copper ions. The fluorescence of the MoS_2QDs was quenched after the addition of copper ions; the reason may be that the transfer of the excited electron from QDs to copper ions leads to the reduction of the radiative recombination.The fluorescence quenching of MoS_2QDs is linearly dependent on the copper ions concentration ranging from 0.1 μM to600 μM, the limit of detection is 0.098 μM, which is much lower than that of existing methods. Moreover, the MoS_2QDs show highly selectivity towards the detection of copper ions.展开更多
基金partially supported by National Natural Science Foundation of China (12274021 and 62075005)。
文摘As typical quarternary copper-based chalcogenides,Cu–Zn–Sn–S nanocrystals(CZTS NCs)have emerged as a newfashioned electrocatalyst in hydrogen evolution reactions(HERs).Oleylamine(OM),a reducing surfactant and solvent,plays a significant role in the assisting synthesis of CZTS NCs due to the ligand effect.Herein,we adopted a facile one-pot colloidal method for achieving the structure evolution of CZTS NCs from 2D nanosheets to 1D nanorods assisted through the continuous addition of OM.During the process,the mechanism of OM-induced morphology evolution was further discussed.When merely adding pure 1-dodecanethiol(DDT)as the solvent,the CZTS nanosheets were obtained.As OM was gradually added to the reaction,the CZTS NCs began to grow along the sides of the nanosheets and gradually shrink at the top,followed by the formation of stable nanorods.In acidic electrolytic conditions,the CZTS NCs with 1.0 OM addition display the optimal HER activity with a low overpotential of 561 m V at 10 m A/cm^(2) and a small Tafel slope of 157.6 m V/dec compared with other CZTS samples.The enhancement of HER activity could be attributed to the contribution of the synergistic effect of the diverse crystal facets to the reaction.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60577020 and 60672004, the National High-Tech Research and Development Program of China under Grant No 2007AA01Z270.
基金supported by the National Natural Science Foundation of China(Nos.10774013,10974013,60978060,and 10804006)the National Natural Science Foundation of China for Distinguished Young Scholars(No.60825407)the Doctor Science Creative Grants of Beijing Jiaotong University(No.141028522)
基金supported by the National High Technology Research and Development Program of China(Grant No.2013AA032205)the Key Project of Beijing Scientific Committee,China(Grant No.D161100003416001)+1 种基金the Fundamental Research Funds for the Central Universities,China(Grant No.2016JBM066)the National Natural Science Foundation of China(Grant Nos.51272022 and 11474018)
文摘Different concentrations of Mg^(2+) -doped hexagonal phase NaGdF_4:Yb^(3+), Er^(3+)nanocrystals(NCs) were synthesized by a modified solvothermal method. Successful codoping of Mg^(2+)ions in upconversion nanoparticles(UCNPs) was supported by XRD, SEM, EDS, and PL analyses. The effects of Mg^(2+)doping on the morphology and the intensity of the upconversion(UC) emission were discussed in detail. It turned out that with the concentration of Mg^(2+)increasing, the morphology of the nanoparticles turn to change gradually and the UC emission was increasing gradually as well. Notably the UC fluorescence intensities of Er^(3+)were gradually improved owing to the codoped Mg^(2+)and then achieved a maximum level as the concentration of Mg^(2+)ions was 60 mol% from the amendment of the crystal structure of β-NaGdF_4:Yb^(3+),Er^(3+)nanoparticles. Moreover, the UC luminescence properties of the rare-earth(Yb3+, Er^(3+)) ions codoped NaGdF_4 nanocrystals were investigated in detail under 980-nm excitation.
文摘The acceleration ability of electrons in SiO2 and ZnS was compared through the variation of emission intensity based on ZnS∶Er electroluminescence during the reverse of polarity of sinusoidal voltage. In order to avoid the influence of work function of electrode, cathodal and anodal materials were ITO （indium tin oxide）. The ratio of maximum emission intensity under positive and negative half period is 2.18. This result demonstrates that the electron acceleration ability of SiO2 is 2.18 times stronger than that of ZnS.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60576016, 10774013, 10804006 and 10434030 （key project）, the National High-Tech Research and Development Program of China under Grant No 2006AA03Z0412, the Natural Science Foundation of Beijing under Grant No 2073030, the National Basic Research Program of China under Grant No 2003CB314707, and Beijing Jiao Tong University under Grants Nos 2005SM057, 2006XM043 and 141028522.
文摘与不同的钒集中做的 ZnO 电影被反应磁控管用一个锌目标劈啪作响与钒做了的 dc 扔到玻璃底层上。钒集中被精力检验散光谱学(版本) 和在 ZnO 薄电影的钒的费用状态被 X 光光电子描绘光谱学。X 光衍射(XRD ) 的结果证明所有这些电影有 wurtzite 结构并且主要在 c 轴取向成长。在扔的电影的谷物尺寸和剩余压力被适合 XRD 结果估计。这些电影的光性质被测量发射度学习。光常数(折射索引和扑灭系数) 和电影厚度被适合发射度获得。所有结果与做钒在关系被讨论。
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10374001, 10434030 and 60576016）, the State Key Development Program for Basic Research of China （Grant No 2003CB314707）, the Excellent Doctor＇s Science and Technology Innovation Foundation of Beijing Jiaotong University （Grant No 48011）, Russian Foundation of Basic Research （Grant Nos 04-02- 16942 and 02-02-39007）.
基金Supported by the National High-Tech Research and Development Programme of China under Grant No 2007AA01Z270, the National Natural Science Foundation of China under Grant No 60877057 and the Ph.D. S＆T Innovation Fund of Beijing Jiaotong University.
基金Supported by the National Basic Research Program of China(2010CB327705)the National Natural Science Foundation of China(10974013 and 51272022)+1 种基金the New Century Excellent Talents in University(NCET-10-0220)the Fundamental Research Funds for the Central Universities(2012JBZ001).
文摘Series devices of ITO/ZnO/ZnO nanorods/MEH-PPV/Al have been fabricated.ITO and ZnO nanorods of some devices are treated by O_(2) plasma.The electroluminescence of different devices is detected under different biases.UV electroluminescence of ZnO nanorods at 380 nm is observed in all the devices.The intensity of 380 nm increases when both ITO and ZnO nanorods are treated.The turn-on voltage of the treated device is lower than that of the non-treated device,and the EL power is enhanced.When the thickness of MEH-PPV is sufficiently thin,only 380 nm electroluminescence,besides a weak defect emission at 760 nm,is detected.The enhancement mechanism of the electroluminescence of the treated devices is discussed.
基金supported by the National Natural Science Foundation of China (10774012 and 10434030)Beijing Jiaotong University Program (2007XM048, 2006XM038)
文摘Nanosized long-persistent phosphors SrS:Eu2+, Dy3+ were prepared by the hydrothermal method.The samples were characterized by X-ray powder diffraction, transmission electron microscopy, and charge-coupled device spectrometry.The persistence characteristic was studied using the decay curves.The results showed that the emission intensity decreased sharply with temperature increasing, although the particle size increased.The S2-vacancies caused by oxidization served as shallow traps, and Dy3+ served as deep traps in SrS:Eu2+, Dy3+.The afterglow intensity of SrS:Eu2+, Dy3+ was higher than that of SrS:Eu2+ prepared at the same temperature.However, the minimization span of initial afterglow with temperature for the former sample was larger than that for the latter.Binary-doped phosphor decayed more slowly than the singly doped one.The afterglow of SrS:Eu2+, Dy3+ decayed more quickly with the increase of sintering temperature.
基金Project(2003CB214501) supported by the National Basic Research Program of China Project(48010) supported by the Excellent Doctor’s Science and Technology Innovation Foundation of Beijing Jiaotong University, China
文摘Sputtering method was used to prepare Ni-Mo alloy electrodes for hydrogen production in alkaline solution. The influences of the working pressure during deposition and the substrate temperature on the electrochemical behavior of electrode were characterized by steady-state polarization plot and Tafel polarization curve measurements. And the physical properties of electrodes were characterized by XRD, SEM, AFM and EDS. It is found that the overpotential is significantly influenced by the working pressure which affects critically the electrode surface morphology, and two Tafel regions are observed for each sample. The overpotential value does not change very much with the substrate temperature. The XRD results indicates that the electrodes should be considered nanocrystalline. Thornton model for the microstructure of sputter-deposited electrodes is referred to explain the observed microstructure change.
基金supported by the National Basic Research Program of China(Grant Nos.2011CB932700 and 2011CB932703)the National Natural Science Foundation of China(Grant Nos.61335006,61378073,and 61077044)+1 种基金the Beijing Natural Science Foundation,China(Grant No.4132031)the Fundamental Research Funds for the Central Universities of Beijing Jiaotong University,China(Grant No.2014YJS136)
文摘In order to investigate the impedance matching properties of microwave absorbers,the ternary nanocomposites of GO/PANI/Fe_3O_4(GPF) are prepared via a two-step method,GO/PANI composites are synthesized by dilute polymerization in the presence of aniline monomer and GO,and GO/PANI/Fe_3O_4 is prepared via a co-precipitation method.The obtained nanocomposites are characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),and Fourier transform infrared spectroscopy(FTIR),respectively.The microwave absorbability reveals enhanced microwave absorption properties compared with GO,PANI,and GO/PANI.The maximum reflection loss of GO/PANI/Fe_3O_4 is up to-27 dB at 14 GHz with its thickness being 2 mm,and its absorption bandwidths exceeding-10 dB are more than 11.2 GHz with its thickness values being in the range from 1.5 mm-4 mm.It provides that GO/PANI/Fe_3O_4 can be used as an attractive candidate for microwave absorbers.
基金supported by the National Natural Science Foundation of China(Grant No.61377028)the Natural Science Funds for Distinguished Young Scholar,China(Grant No.61125505)the Fundamental Research Funds for the Central Universities,China(Grant No.2014JBZ009)
文摘N-dodecanethiol capped zinc sulfide(Zn S) nanocrystals were synthesized by the one-pot approach and blended with poly(N-vinylcarbazole)(PVK) to fabricate electrical bistable devices. The corresponding devices did exhibit electrical bistability and negative differential resistance(NDR) effects. A large ON/OFF current ratio of 104 at negative voltages was obtained by applying different amplitudes of sweeping voltage. The observed conductance switching and the negative differential resistance are attributed to the electric-field-induced charge transfer between the nanocrystals and the polymer,and the charge trapping/detrapping in the nanocrystals.
基金Project supported bythe National Natural Science Foundation of China (60576016 ,10374001) Natural Science Foundationof Beijing (2073030) +1 种基金"973"National Key Basic Research Foundation of China (2003CB314707) National Natural Sci-ence Foundation of China (10434030)
文摘A novel rare earth complex Eu(TTA)2(N-HPA)Phen (TTA=thenoyltrifluoroacetone, N-HPA=N-phenylanthranilic acid, and phen=1,10-phenathroline), which contains three different ligands, was synthesized. The Eu complex was blended with poly N-vinylcarbazole (PVK) in different weight ratios and spin coated into films. The luminescence properties of films were investigated and energy transfer between PVK and the complex was discussed. Multilayer structural devices consisting of ITO/PVK∶Eu(TTA)2(N-HPA)phen/BCP/Alq3/A1 were fabricated with PVK∶Eu(TTA)2(N-HPA) as light-emitting layer. Increasing the concentration of Eu in the PVK thin film would inhibit the emission of PVK to different degrees. Finally, the pure red luminescence of europium(Ⅲ) was observed when the doping weight ratio was approximately 1∶5, which indicated an effective energy transfer from PVK to rare earth complex.
基金Supported by the National Natural Science Foundation of China under Grant No 50972007the Beijing Municipal Natural Science Foundation under Grant No 4092035+2 种基金the National Basic Research Program of China under Grant No 2011CB932703the National Science Fund for Distinguished Young Scholars under Grant No 60825407the Special Items Fund of the Beijing Municipal Commission of Education,and the Opened Fund of the State Key Laboratory on Integrated Optoelectronics.
文摘We report on the fabrication and electrical characteristics of Ga-doped ZnO thin film transistors(TFTs).Low Ga-doped(0.7wt%)ZnO thin films were deposited on SiO_(2)/p−Si substrates by rf magnetron sputtering.The GZO TFTs show a mobility of 1.76 cm2/V⋅s,an on/off ratio of 1.0×10^(6),and a threshold voltage of 35 V.The time−dependent instability of the TFT is studied.The VTH shifts negatively.In addition,the device shows a decrease of the on/off ratio,mainly due to the increase of the off-current.The mechanisms of instability are discussed.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60978060, 10804006, and 10974013)the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20090009110027)+4 种基金the Research Fund for the Youth Scholars of the Doctoral Program of Higher Education, China (Grant No. 20070004031)the Beijing Municipal Natural Science Foundation of China (Grant No. 1102028)the Beijing Municipal Science & Technology Commission of China (Grant No. Z090803044009001)the National Basic Research Program of China (Grant No. 2010CB327705)the International Science and Technology Cooperation Program (Grant No. 2008DFA61420)
文摘In this work, bathocuproine (BCP) and bathophenanthroline (Bphen), commonly used in small-molecule organic solar cells (OSCs), are adopted as the buffer layers to improve the performance of the polymer solar cells (PSCs) based on poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV): [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction. By inserting BCP or Bphen between the active layer and the top cathode, all the performance parameters are dramatically improved. The power conversion efficiency is increased by about 70% and 120% with 5-nm BCP and 12-nm Bphen layers, respectively, when compared with that of the devices without any buffer layer. The performance enhancement is attributed to BCP or Bphen (i) increasing the optical field, and hence the absorption in the active layer, (ii) effectively blocking the excitons generated in MEH-PPV from quenching at organic/aluminum (Al) interface due to the large band-gap of BCP or Bphen, which results in a significant reduction in series resistance (Rs), and (iii) preventing damage to the active layer during the metal deposition. Compared with the traditional device using LiF as the buffer layer, the BCP-based devices show a comparable efficiency, while the Bphen-based devices show a much larger efficiency. This is due to the higher electron mobility in Bphen than that in BCP, which facilitates the electron transport and extraction through the buffer layer to the cathode.
基金supported by the National Natural Science Foundation of China (10644002)Beijing Municipal Science & Technology Commission Foundation (Y0406001040711)the Foundation of Beijing Jiaotong University (2006XM051)
文摘A series of Eu2+-doped fluorochlorozirconate glass-ceramics were prepared by solid state reaction method. X-ray diffraction, pho-toluminescence, photo-stimulated luminescence (PSL) and the turbidity of fluorozirconate glass containing BaCl2 nano- and micro-crystals were measured for the samples annealed at 290 °C for 10 min. The PSL was attributed to the characteristic emission of Eu2+ in nano-crystallites of BaCl2, which formed in the glass upon annealing. The PSL efficiency of the glass ceramic was increased by increasing the concentration of BaCl2, which, however, resulted in the decreasing in the transparency of the sample. The sample turned to a semi-transparent glass ceramic or even an opaque and milky white one from a near-transparent glass. The trade-off between optical trans-parency and PSL intensity over different concentrations of BaCl2 for X-ray imaging plate applications was briefly discussed.
基金the financial supporting from the NSFC(61975006,61675017)NSFRPSI(Y72Z090Q10)+3 种基金the NSFCQ(cstc2019jcyj-msxm X0400)the NYTPP(R52A199Z11)the YIPACAS(E0296104)the BNSF(4192049)。
文摘Small molecule organic photovoltaics(SMPVs) were prepared by utilizing liquid crystalline donor material BTR-Cl and two similar optical bandgap non-fullerene acceptor materials BTP-BO-4 F and Y6.The BTPBO-4 F and Y6 have the similar optical bandgap and different absorption coefficients.The corresponding binary SMPVs exhibit different short circuit current density(/sc)(20.38 vs.23.24 mA cm^(-2)),and fill factor(FF)(70.77% vs.67.21%).A 14.46% power conversion efficiency(PCE) is acquired in ternary SMPVs with 30 wt% Y6,companied with a JSC of 24.17 mA cm^(-2) a FF of 68.78% and an open circuit voltage(Voc) of 0.87 V.The improvement on PCE of ternary SMPVs should originate from the well trade-off between phase separation and photon harvesting of ternary active layers by incorporating 30 wt% Y6 in acceptors.This work may deliver insight onto the improved performance of SMPVs by superposing the superiorities of binary SMPVs with similar optical bandgap acceptors into one ternary cell.
基金Project(B201015)supported by the Natural Science Foundation of Heilongjiang Province,ChinaProject(11551482)supported by the Scientific and Technical Research Project of Education Department of Heilongjiang Province,China+3 种基金Projects(L2010-124,L2010-144)supported by the Research Fund for Jiamusi University,ChinaProject(E08050204)supported by the Research Fund for the Provincial Key Laboratory of Biomaterials Jiamusi University,ChinaProject(2009-360)supported by Health Commission of Heilongjiang Province,ChinaProject supported by Key Laboratory of Luminescence and Optical Information,Beijing Jiaotong University,China
文摘The rare earth ternary complex of Eu 3+ with thenoyltrifluoroacetone,and 4,7-2NH2 phenanthroline was synthesized and well characterized by UV,fluorescent,IR spectrometry and X-ray diffractometry(XRD)as well as elemental analysis.The results show that the complex of Eu(III)emits strong red luminescence when excited by UV light,and Eu(TTA)3(2NH2-Phen)has the higher sensitized luminescent efficiency and longer lifetime than Eu(TTA)3(Phen).In device of ITO/PVK/Eu(TTA)3(2NH2-Phen)/Al,the spectra of Eu(TTA)3(2NH2-Phen)with different ratios for spin-cast film were monitored.The main emitting peak at 614 nm can be attributed to the transition of 5 D0→ 7 F2 of Eu 3+ and this process results in the enhancement of red emission from electroluminescence device.The effect and mechanism of the ligands on the luminescence properties of europium complex were discussed.The results show that the luminescence intensity of the title complexes greatly increases in comparison with that of their corresponding complexes,revealing that the second ligands form very good synergistic effect with the first ligands.The title complexes possess excellent thermal stability properties,and are hopefully developed into fine PL and EL red materials.
基金Project supported by the National Key R&D Program of China(Grant No.2016YFA0202302)the National Natural Science Foundation of China(Grant Nos.61335006,61527817,and 61378073)+1 种基金the Overseas Expertise Introduction Center for Discipline Innovation,111 Center,Chinathe National Basic Research Program of China(Grant No.KSJB17030536)
文摘Molybdenum disulfide quantum dots(MoS_2QDs) were synthesized via a hydrothermal method using sodium molybdate and cysteine as molybdenum and sulfur sources, respectively. The optimal hydrothermal time was studied. Furthermore, the as synthesized water-soluble MoS_2QDs were used as a fluorescence probe for the sensitive and selective detection of copper ions. The fluorescence of the MoS_2QDs was quenched after the addition of copper ions; the reason may be that the transfer of the excited electron from QDs to copper ions leads to the reduction of the radiative recombination.The fluorescence quenching of MoS_2QDs is linearly dependent on the copper ions concentration ranging from 0.1 μM to600 μM, the limit of detection is 0.098 μM, which is much lower than that of existing methods. Moreover, the MoS_2QDs show highly selectivity towards the detection of copper ions.
