A novel WO3-x/TiO2 film as photoanode was synthesized for photoelectrocatalytic(PEC) reduction of CO2 into formic acid(HCOOH). The films prepared by doctor blade method were characterized with X-ray diffractometer...A novel WO3-x/TiO2 film as photoanode was synthesized for photoelectrocatalytic(PEC) reduction of CO2 into formic acid(HCOOH). The films prepared by doctor blade method were characterized with X-ray diffractometer(XRD), scanning electron microscope(SEM) and transmission electron microscope(TEM). The existence of oxygen vacancies in the WO3-x was confirmed with an X-ray photoelectron spectroscopy(XPS), and the accurate oxygen index was determined by a modified potentiometric titrimetry method. After 3h of photoelectrocatalytic reduction, the formic acid yield of the WO3-x/TiO2 film is 872 nmol/cm^2, which is 1.83 times that of the WO3/TiO2 film. The results of PEC performance demonstrate that the introduction of WO3-x nanoparticles can improve the charge transfer performance so as to enhance the performance of PEC reduction of CO2 into formic acid.展开更多
A thin layer of TiO2 film was deposited on ITO surface via the liquid phase deposition (LPD) process. The photocurrent and electrochemical impedance spectroscopy (EIS) measurements indicated that the as-prepared L...A thin layer of TiO2 film was deposited on ITO surface via the liquid phase deposition (LPD) process. The photocurrent and electrochemical impedance spectroscopy (EIS) measurements indicated that the as-prepared LPD TiO2/ITO film had an excellent photoelectrochemical performance, which showed a sensitive and rapid response to the UV irradiation. The photogenerated electron-hole pairs could be effectively separated by applying an external bias to the TiO2 film electrode. The LPD TiO2/ITO film was employed to study the photoelectrocatalytic (PEC) degradation of 4-aminoantipyrine. Compared with other techniques, the PEC technique based on such a LPD film electrode had a synergetic effect for 4-aminoantipyrine degradation. When the applied bias potential was+0.8 V and the supporting electrolyte concentration of Na2SO4 was 0.1 mol/L, the highest degradation efficiency within 120 min could reach 95%for 0.1 mmol/L 4-aminoantipyrine solution at pH 2.0.展开更多
Zn-doped TiO2 (Zn?TiO2) thin films were prepared by the sol?gel method on titanium substrates with heat treatment at different temperatures. The effects of heat treatment temperatures and Zn doping on the structure, p...Zn-doped TiO2 (Zn?TiO2) thin films were prepared by the sol?gel method on titanium substrates with heat treatment at different temperatures. The effects of heat treatment temperatures and Zn doping on the structure, photocathodic protection and photoelectrochemical properties of TiO2 thin films were investigated. It is indicated that the photoelectrical performance of the Zn?TiO2 films is enhanced with the addition of Zn element compared with the pure-TiO2 film and the largest decline by 897 mV in the electrode potential is achieved under 300 °C heat treatment. SEM?EDS analyses show that Zn element is unevenly distributed in Zn?TiO2 films; XRD patterns reveal that the grain size of Zn?TiO2 is smaller than that of pure-TiO2; FTIR results indicate that Zn - O bond forms on Zn?TiO2 surface. Ultraviolet visible absorption spectra prove that Zn?TiO2 shifts to visible light region.Mott?Shottky curves show that the flat-band potential of Zn?TiO2 is more negative and charge carrier density is bigger than that ofpure-TiO2, implying that under the synergy of the width of the space-charge layer, carrier density and flat-band potential, Zn?TiO2 with 300 °C heat treatment displays the best photocathodic protection performance.展开更多
The hole injection,the radiative recombination and the device luminescent efficiencies of amorphous silicon carbide thin film p-i-n junction light emitting diodes are quantitatively calculated,and the effect of the ca...The hole injection,the radiative recombination and the device luminescent efficiencies of amorphous silicon carbide thin film p-i-n junction light emitting diodes are quantitatively calculated,and the effect of the carrier(especially the hole) injection and recombination processes on the device luminescent characteristics are revealed.Without considering the device junction temperature,it is found that the device luminescent efficiency mainly depends on the hole injection efficiency at low field and the hole radiative recombination efficiency at high field respectively.The theoretical analyses are in well agreement with the experimental results.展开更多
We synthesized a mesoporous film based on TiO2-reduced graphene oxide(RGO)hybrids using a one-step vapor-thermal method without the need for an additional annealing process.The vapor-thermally prepared TiO2-graphene h...We synthesized a mesoporous film based on TiO2-reduced graphene oxide(RGO)hybrids using a one-step vapor-thermal method without the need for an additional annealing process.The vapor-thermally prepared TiO2-graphene hybrid(VTH)features unique structures with an ultra-large specific surface area of^260 m^2 g^-1 and low aggregation,giving rise to enhanced light harvesting and increased charge generation and separation efficiency.It was observed that a mesoporous film with uniform pore distribution is simultaneously obtained during the VTH growth process.When a 5.0 wt%RGO VTH film was used as the active layer in photocatalysis,the highest photocatalytic activity for degradation of methyl orange was achieved.For another,when a 0.75 wt%RGO VTH film was used as the photoanode in a dye-sensitized solar cell,the power conversion efficiency reached 7.58%,which represents an increase of 73.1%compared to a solar cell using an a photoanode of pure TiO2 synthesized by a traditional solvothermal method.It is expected that this facile method for the synthesis of TiO2/graphene hybrid mesoporous films will be useful in practical applications for preparing other metal oxide/graphene hybrids with ultra-high photocatalytic activity and photovoltaic performance.展开更多
Self-made TiO2 nanoparticles were used as photoelectrode material of dye sensitized solar cell. The TiO2 thin film coats through spreading nanoparticles evenly onto the ITO glass via self-made spin-heat platform, and ...Self-made TiO2 nanoparticles were used as photoelectrode material of dye sensitized solar cell. The TiO2 thin film coats through spreading nanoparticles evenly onto the ITO glass via self-made spin-heat platform, and then TiO2 thin film is soaked in the dye N-719 more than 12 h to prepare the photoelectrode device. The TiO2 nanoparticles produced by electric-discharge-nanofluid-process have premium anatase crystal property, and its diameter can be controlled within a range of 20-50 nm. The surface energy zeta potential of nanofluid is from -22 mV to -28.8 mV, it is a stable particle suspension in the deionized water. A trace of surfactant Triton X-100 put upon the surface of ITO glass can produce a uniform and dense TiO2 thin film and heating up the spin platform to 200 oC is able to eliminate mixed surfac-tant. Self-made TiO2 film presents excellent dye absorption performance and even doesn't need heat treatment procedure to enhance essential property. Results of energy analysis show the thicker film structure will increase the short-circuit current density that causes higher conversion efficiency. But, as the film structure is large and thick, both the open-circuit voltage and fill factor will decline gradually to lead bad efficiency of dye-sensitized solar cell.展开更多
The photo-corrosion of electrodeposited polycrystalline CdSe electrode was inhibited effectively by coating a thin layer of the conductive polyaniline (PAN) film. The relation between the performance and internal ba...The photo-corrosion of electrodeposited polycrystalline CdSe electrode was inhibited effectively by coating a thin layer of the conductive polyaniline (PAN) film. The relation between the performance and internal band structure of such film-covered PAN/CdSe electrode was studied by the electrochemical modulation reflectance spectrum (EMRS). EMRS of both CdSe and PAN/CdSe electrodes in K4Fe(CN)6/K3Fe(CN)6 solution exhibited typical France-Keidysh oscillations, by which the values of the energy gap and flat band potential were determined. The EMRS results indicated that the energy band structure of CdSe electrode was not changed after coated with PAN film, so that the photoelectrochemical characteristic of PAN/CdSe electrode was rather similar to that of CdSe electrode.展开更多
A novel device, lateral PIN photodiode gated by transparent electrode (LPIN PD-GTE) fabricated on fully-depleted SOI film was proposed. ITO film was adopted in the device as gate electrode to reduce the light absorp...A novel device, lateral PIN photodiode gated by transparent electrode (LPIN PD-GTE) fabricated on fully-depleted SOI film was proposed. ITO film was adopted in the device as gate electrode to reduce the light absorption. Thin Si film was fully depleted under gate voltage to achieve low dark current and high photo4o-dark current ratio. The model of gate voltage was obtained and the numerical simulations were presented by ATLAS. Current-voltage characteristics of LPIN PD-GTE obtained in dark (dark current) and under 570 nm illumination (photo current) were studied to achieve the greatest photo-to-dark current ratio for active channel length from 2 to 12 /am. The results show that the photo-to-dark current ratio is 2.0×10^7, with dark current of around 5×10^-4 pA under VGK=0.6 V, PrN=5 mW/cm2, for a total area of 10μm×10μm in fully depleted SOI technology. Thus, the LPIN PD-GTE can be suitable for high-grade photoelectric systems such as blue DVD.展开更多
Thin films of ZnO were electrodeposited from an aqueous solution of Zn(NO3 )2 on indium tin oxide(ITO)-covered glass substrate. The analysis of X-ray diffraction(XRD) and scanning electron micrograph (SEM) ind...Thin films of ZnO were electrodeposited from an aqueous solution of Zn(NO3 )2 on indium tin oxide(ITO)-covered glass substrate. The analysis of X-ray diffraction(XRD) and scanning electron micrograph (SEM) indicated that the obtained ZnO films had a compact hexagonal wurtzite type structure with preferable (002) growth direction. A sharp near-UV emission peak located at 380 nm and a strong orange-red emission peak located at 593 nm were observed in the photoluminescence, when excited with 325 nm wavelength at room temperature. Then the prepared ZnO films were introduced as anode phosphors into the field emission test. It was found that orange-red cathode-luminescence was observed and the luminescent brightness was enhanced by annealing. When annealing temperature increased about 600 ℃, the photoluminescence with peak of 531 nm and the green cathode-luminescence were observed. The tests showed that the brightness of about 2 × 102 cd/m^2 was obtained at electric field of 2 V/μm for annealed sample. The results revealed that the film could be a good kind of low-voltage drived cathode-luminescence phosphor.展开更多
This paper proposes a new mechanism to explain the performance of thin dye-sensitized solar cells (DSSC). Near-stoichiometric flower-like Cu2ZnSnS4 (CZTS) microspheres with a high specific surface area was fabri- ...This paper proposes a new mechanism to explain the performance of thin dye-sensitized solar cells (DSSC). Near-stoichiometric flower-like Cu2ZnSnS4 (CZTS) microspheres with a high specific surface area was fabri- cated for use as the photocathode in a DSSC. To improve the extraction and transfer of electrons, graphene was added to the CZTS. A DSSC with a 10-gin TiO2 pho- toanode layer exhibited a slightly degraded efficiency with a CZTS-graphene photocathode, relative to a Pt counter electrode (CE). Nevertheless, when the thickness of the TiO2 photoanode was reduced to 2 lam, the efficiency of a DSSC with a CZTS-graphene photocathode was greater than that of a Pt-DSSC. It is speculated that, unlike the Pt CE, a CZTS-graphene photocathode not only collects electrons from an external circuit and catalyzes the reduction of the triiodide ions in the electrolyte, but also utilizes unabsorbed photons to produce photo-excited electrons and suppresses charge recombination, thus enhancing the performance of the cell. The use of narrowband gap p-type semiconductors as photocathodes offers a new means of fabricating thin dye-sensitized solar cells and effectively improving the cell performance.展开更多
An accurate measurement of the refractive index is necessary for the optical design of both deep ultraviolet laser diodes and light-emitting diodes. Generally, the refractive indices along different crystallographic a...An accurate measurement of the refractive index is necessary for the optical design of both deep ultraviolet laser diodes and light-emitting diodes. Generally, the refractive indices along different crystallographic axes of anisotropic thin films are measured using variable angle spectroscopic ellipsometry.However, there are still some limitations concerning this method. Here we proposed a potential method to measure the band edge refractive index of wide bandgap semiconductor. An aperiodic oscillation emission phenomenon due to the Fabry-Perot effect was observed in the fluorescence spectrum of an AlN film with a thickness of 1500 nm. Based on the characteristics of the fluorescence spectrum and the definition of Fabry-Perot effect, we obtained the ordinary refractive index of the AlN thin film near the band edge directly. This refractive index measurement method is a supplement to the variable angle ellipsometry,and it is a more direct and effective method for transferred film and thinner samples to measure the fluorescence spectrum.展开更多
How to control the dipole orientation of organic emitters is a challenge in the field of organic light-emitting diodes(OLEDs).Herein,a linear thermally activated delayed fluorescence(TADF)molecule,PhNAI-PMSBA,bearing ...How to control the dipole orientation of organic emitters is a challenge in the field of organic light-emitting diodes(OLEDs).Herein,a linear thermally activated delayed fluorescence(TADF)molecule,PhNAI-PMSBA,bearing a 1,8-naphthalimide-acridine framework was designed by a doublesite long-axis extension strategy to actively control the dipole orientation.The horizontal ratio of emitting dipole orientation of PhNAI-PMSBA reaches 95%,substantially higher than that of isotropic emitters(67%).This unique feature is associated with the intrinsically horizontal molecular orientation of PhNAI-PMSBA and the good agreement between its transition dipole moment direction and molecular long axis.The PhNAI-PMSBA-based OLED achieves an ultrahigh optical outcoupling efficiency of 43.2%and thus affords one of the highest red electroluminescence with an external quantum efficiency of 22.3%and the Commission International de l’Eclairage 1931 coordinates at around(0.60,0.40).展开更多
Titanium dioxide (TiO2) thin films were grown onto Indium tin oxide (ITO) glass under atmospheric pressure by chemical va- por deposition (AP-MOCVD) using titanium tetraisopropoxide astitanium precursor. The as-...Titanium dioxide (TiO2) thin films were grown onto Indium tin oxide (ITO) glass under atmospheric pressure by chemical va- por deposition (AP-MOCVD) using titanium tetraisopropoxide astitanium precursor. The as-prepared TiOe/ITO films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and photoelectrochemical measurements. Their photocatalytic (PC) and photoelec- trocatalytic (PEC) activities were evaluated based on the results of methyl orange dye (MO) degradation experiments in aque- ous solution. The difference between the front side (EE, electrolyte/electrode interface) and the back side (SE, sub- strate/electrode interface) illumination was evaluated in both photocurrent and MO degradation experiments. The effect of the film thickness on degradation rate by PEC under the two illumination directions was also studied. Stability of TiO2/ITO film electrode was investigated in repetitive degradation experiments. Overall, the TiO2/ITO film with thickness ranging from 321 to1440 nm deposited by MOCVD method is an effective photoelectrode for MO degradation under SE illumination in PEC reaction system.展开更多
SnO2 nanosheet films about 200 nm in thickness are successfully fabricated on fluorine-doped tin oxide (FTO) glass by a facile solution-grown approach. The prepared SnO2 nanosheet film is appfied as an interfacial l...SnO2 nanosheet films about 200 nm in thickness are successfully fabricated on fluorine-doped tin oxide (FTO) glass by a facile solution-grown approach. The prepared SnO2 nanosheet film is appfied as an interfacial layer between the nanocrystalline TiO2 film and the FTO substrate in dye-sensitized solar cells (DSCs). Experimental results show that the introduction of a SnO2 nanosheet film not only suppresses the electron back-transport reaction at the electrolyte/FTO interface but also provides an efficient electron transition channel along the SnO2 nanosheets, and as a result, increasing the open circuit voltage and short current density, and finally improving the conversion efficiency for the DSCs from 3.89% to 4.62%.展开更多
ZnO-TiO2 hybrid photoanodes were fabricated via the doctor-blade method by integrating vertically-grown sparse ZnO arrays with hydrothermal TiO2 nanoparticles. A special surface-coating technique was developed to depo...ZnO-TiO2 hybrid photoanodes were fabricated via the doctor-blade method by integrating vertically-grown sparse ZnO arrays with hydrothermal TiO2 nanoparticles. A special surface-coating technique was developed to deposit a thin TiO2 layer on the surface of ZnO rods. Microstructure, optical and photoelectrochemical performance of the hybrid photoanodes were investigated. The denser ZnO array exhibited bad filling behavior of nanoparticles in the interspace of ZnO rods, strong scattering and low conversion efficiency (0.27%). The sparser array showed a much better integrated microstructure, improved transmittance and high conversion efficiency (2.68%). The surface modification of ZnO rods by the TiO2 thin layer was found useful in improving the interfacial microstructure between the ZnO rod and the TiO2 bulk film, and the total conversion efficiency of 3.01% was achieved, higher than that of the pure TiO2 nanoparticle cell (2.93%). The increased scattering effects on the incident light, the enhanced electron transportation at TiO2/dye/electrolyte interface, and the inhabited recombination were responsible for this improvement.展开更多
n-Si,believed as a promising photoanode candidate,has suffered from sluggish oxygen evolution reaction(OER)kinetics and poor chemical stability when exposed to aqueous electrolyte.Herein,CoO_(x)/Ni:CoOOH bilayers were...n-Si,believed as a promising photoanode candidate,has suffered from sluggish oxygen evolution reaction(OER)kinetics and poor chemical stability when exposed to aqueous electrolyte.Herein,CoO_(x)/Ni:CoOOH bilayers were successfully deposited on n-Si substrate by atomic layer-deposition(ALD)and photoassisted electrochemical deposition(PED)for stabilizing and catalyzing photoelectrochemical(PEC)water oxidation.In comparison to the n-Si/CoO_(x)photoanode as reference,the prepared n-Si/CoO_(x)/Ni:CoOOH photoanode upon the optimized PED process presents a much improved PEC performance for water splitting,with the onset potential cathodically shifted to~1.03 V vs.reversible hydrogen electrode(RHE)and the photocurrent density much increased to 20 mA cm^(−2)at 1.23 V vs.RHE.It is revealed that the introduction of Ni dopants increases the work functions of the deposited Ni:CoOOH overlayers,which gives rise to the upward band bending weakened at the n-Si/CoO_(x)/Ni:CoOOH cascading interface while strengthened at the Ni:CoOOH/electrolyte interface(with the band bending shifted from downward to upward),contributing to the decreased and the increased driving forces for charge transfer at the interfaces,respectively.Then,the balanced driving forces at the interfaces would endow the n-Si/CoO_(x)/Ni:CoOOH photoanode with the best PEC performance.Moreover,PED has been evidenced superior to ED to dope Ni into CoOOH with the formed overlayer effectively catalyzing and stabilizing PEC water splitting.展开更多
基金Project(21471054)supported by the National Natural Science Foundation of China
文摘A novel WO3-x/TiO2 film as photoanode was synthesized for photoelectrocatalytic(PEC) reduction of CO2 into formic acid(HCOOH). The films prepared by doctor blade method were characterized with X-ray diffractometer(XRD), scanning electron microscope(SEM) and transmission electron microscope(TEM). The existence of oxygen vacancies in the WO3-x was confirmed with an X-ray photoelectron spectroscopy(XPS), and the accurate oxygen index was determined by a modified potentiometric titrimetry method. After 3h of photoelectrocatalytic reduction, the formic acid yield of the WO3-x/TiO2 film is 872 nmol/cm^2, which is 1.83 times that of the WO3/TiO2 film. The results of PEC performance demonstrate that the introduction of WO3-x nanoparticles can improve the charge transfer performance so as to enhance the performance of PEC reduction of CO2 into formic acid.
基金Projects(12JJ3013,11JJ5010,10JJ5002)supported by the Natural Science Foundation of Hunan Province,ChinaProject(2013CL04)supported by the Hunan Provincial Key Laboratory of Materials Protection for Electric Power and Transportation,Changsha University of Science and Technology,ChinaProject(2011RS4069)supported by the Planned Science and Technology Program of Hunan Province,China
文摘A thin layer of TiO2 film was deposited on ITO surface via the liquid phase deposition (LPD) process. The photocurrent and electrochemical impedance spectroscopy (EIS) measurements indicated that the as-prepared LPD TiO2/ITO film had an excellent photoelectrochemical performance, which showed a sensitive and rapid response to the UV irradiation. The photogenerated electron-hole pairs could be effectively separated by applying an external bias to the TiO2 film electrode. The LPD TiO2/ITO film was employed to study the photoelectrocatalytic (PEC) degradation of 4-aminoantipyrine. Compared with other techniques, the PEC technique based on such a LPD film electrode had a synergetic effect for 4-aminoantipyrine degradation. When the applied bias potential was+0.8 V and the supporting electrolyte concentration of Na2SO4 was 0.1 mol/L, the highest degradation efficiency within 120 min could reach 95%for 0.1 mmol/L 4-aminoantipyrine solution at pH 2.0.
基金Project(cstc2011jj A50008)supported by the Natural Science Foundation of Chongqing,ChinaProject(14ZB0025)supported by Education Department of Sichuan Province,China
文摘Zn-doped TiO2 (Zn?TiO2) thin films were prepared by the sol?gel method on titanium substrates with heat treatment at different temperatures. The effects of heat treatment temperatures and Zn doping on the structure, photocathodic protection and photoelectrochemical properties of TiO2 thin films were investigated. It is indicated that the photoelectrical performance of the Zn?TiO2 films is enhanced with the addition of Zn element compared with the pure-TiO2 film and the largest decline by 897 mV in the electrode potential is achieved under 300 °C heat treatment. SEM?EDS analyses show that Zn element is unevenly distributed in Zn?TiO2 films; XRD patterns reveal that the grain size of Zn?TiO2 is smaller than that of pure-TiO2; FTIR results indicate that Zn - O bond forms on Zn?TiO2 surface. Ultraviolet visible absorption spectra prove that Zn?TiO2 shifts to visible light region.Mott?Shottky curves show that the flat-band potential of Zn?TiO2 is more negative and charge carrier density is bigger than that ofpure-TiO2, implying that under the synergy of the width of the space-charge layer, carrier density and flat-band potential, Zn?TiO2 with 300 °C heat treatment displays the best photocathodic protection performance.
文摘The hole injection,the radiative recombination and the device luminescent efficiencies of amorphous silicon carbide thin film p-i-n junction light emitting diodes are quantitatively calculated,and the effect of the carrier(especially the hole) injection and recombination processes on the device luminescent characteristics are revealed.Without considering the device junction temperature,it is found that the device luminescent efficiency mainly depends on the hole injection efficiency at low field and the hole radiative recombination efficiency at high field respectively.The theoretical analyses are in well agreement with the experimental results.
文摘We synthesized a mesoporous film based on TiO2-reduced graphene oxide(RGO)hybrids using a one-step vapor-thermal method without the need for an additional annealing process.The vapor-thermally prepared TiO2-graphene hybrid(VTH)features unique structures with an ultra-large specific surface area of^260 m^2 g^-1 and low aggregation,giving rise to enhanced light harvesting and increased charge generation and separation efficiency.It was observed that a mesoporous film with uniform pore distribution is simultaneously obtained during the VTH growth process.When a 5.0 wt%RGO VTH film was used as the active layer in photocatalysis,the highest photocatalytic activity for degradation of methyl orange was achieved.For another,when a 0.75 wt%RGO VTH film was used as the photoanode in a dye-sensitized solar cell,the power conversion efficiency reached 7.58%,which represents an increase of 73.1%compared to a solar cell using an a photoanode of pure TiO2 synthesized by a traditional solvothermal method.It is expected that this facile method for the synthesis of TiO2/graphene hybrid mesoporous films will be useful in practical applications for preparing other metal oxide/graphene hybrids with ultra-high photocatalytic activity and photovoltaic performance.
文摘Self-made TiO2 nanoparticles were used as photoelectrode material of dye sensitized solar cell. The TiO2 thin film coats through spreading nanoparticles evenly onto the ITO glass via self-made spin-heat platform, and then TiO2 thin film is soaked in the dye N-719 more than 12 h to prepare the photoelectrode device. The TiO2 nanoparticles produced by electric-discharge-nanofluid-process have premium anatase crystal property, and its diameter can be controlled within a range of 20-50 nm. The surface energy zeta potential of nanofluid is from -22 mV to -28.8 mV, it is a stable particle suspension in the deionized water. A trace of surfactant Triton X-100 put upon the surface of ITO glass can produce a uniform and dense TiO2 thin film and heating up the spin platform to 200 oC is able to eliminate mixed surfac-tant. Self-made TiO2 film presents excellent dye absorption performance and even doesn't need heat treatment procedure to enhance essential property. Results of energy analysis show the thicker film structure will increase the short-circuit current density that causes higher conversion efficiency. But, as the film structure is large and thick, both the open-circuit voltage and fill factor will decline gradually to lead bad efficiency of dye-sensitized solar cell.
文摘The photo-corrosion of electrodeposited polycrystalline CdSe electrode was inhibited effectively by coating a thin layer of the conductive polyaniline (PAN) film. The relation between the performance and internal band structure of such film-covered PAN/CdSe electrode was studied by the electrochemical modulation reflectance spectrum (EMRS). EMRS of both CdSe and PAN/CdSe electrodes in K4Fe(CN)6/K3Fe(CN)6 solution exhibited typical France-Keidysh oscillations, by which the values of the energy gap and flat band potential were determined. The EMRS results indicated that the energy band structure of CdSe electrode was not changed after coated with PAN film, so that the photoelectrochemical characteristic of PAN/CdSe electrode was rather similar to that of CdSe electrode.
基金Project(61040061) supported by the National Natural Science Foundation of ChinaProject supported by Hunan Provincial Innovation Foundation for Postgraduate Students,China
文摘A novel device, lateral PIN photodiode gated by transparent electrode (LPIN PD-GTE) fabricated on fully-depleted SOI film was proposed. ITO film was adopted in the device as gate electrode to reduce the light absorption. Thin Si film was fully depleted under gate voltage to achieve low dark current and high photo4o-dark current ratio. The model of gate voltage was obtained and the numerical simulations were presented by ATLAS. Current-voltage characteristics of LPIN PD-GTE obtained in dark (dark current) and under 570 nm illumination (photo current) were studied to achieve the greatest photo-to-dark current ratio for active channel length from 2 to 12 /am. The results show that the photo-to-dark current ratio is 2.0×10^7, with dark current of around 5×10^-4 pA under VGK=0.6 V, PrN=5 mW/cm2, for a total area of 10μm×10μm in fully depleted SOI technology. Thus, the LPIN PD-GTE can be suitable for high-grade photoelectric systems such as blue DVD.
基金Science and Technology Foundation of Education Ministry of China(205091)
文摘Thin films of ZnO were electrodeposited from an aqueous solution of Zn(NO3 )2 on indium tin oxide(ITO)-covered glass substrate. The analysis of X-ray diffraction(XRD) and scanning electron micrograph (SEM) indicated that the obtained ZnO films had a compact hexagonal wurtzite type structure with preferable (002) growth direction. A sharp near-UV emission peak located at 380 nm and a strong orange-red emission peak located at 593 nm were observed in the photoluminescence, when excited with 325 nm wavelength at room temperature. Then the prepared ZnO films were introduced as anode phosphors into the field emission test. It was found that orange-red cathode-luminescence was observed and the luminescent brightness was enhanced by annealing. When annealing temperature increased about 600 ℃, the photoluminescence with peak of 531 nm and the green cathode-luminescence were observed. The tests showed that the brightness of about 2 × 102 cd/m^2 was obtained at electric field of 2 V/μm for annealed sample. The results revealed that the film could be a good kind of low-voltage drived cathode-luminescence phosphor.
基金This work was supported by the National Natural Science Foundation of China (51272033, 51572037 and 51335002), the Priority Academic Program Development of Jiangsu Higher Education Institutions and the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (14KJA430001).
文摘This paper proposes a new mechanism to explain the performance of thin dye-sensitized solar cells (DSSC). Near-stoichiometric flower-like Cu2ZnSnS4 (CZTS) microspheres with a high specific surface area was fabri- cated for use as the photocathode in a DSSC. To improve the extraction and transfer of electrons, graphene was added to the CZTS. A DSSC with a 10-gin TiO2 pho- toanode layer exhibited a slightly degraded efficiency with a CZTS-graphene photocathode, relative to a Pt counter electrode (CE). Nevertheless, when the thickness of the TiO2 photoanode was reduced to 2 lam, the efficiency of a DSSC with a CZTS-graphene photocathode was greater than that of a Pt-DSSC. It is speculated that, unlike the Pt CE, a CZTS-graphene photocathode not only collects electrons from an external circuit and catalyzes the reduction of the triiodide ions in the electrolyte, but also utilizes unabsorbed photons to produce photo-excited electrons and suppresses charge recombination, thus enhancing the performance of the cell. The use of narrowband gap p-type semiconductors as photocathodes offers a new means of fabricating thin dye-sensitized solar cells and effectively improving the cell performance.
基金This work was financially supported by the National Natural Science Foundation of China(91333207,61427901,61604178,91833301 and U1505252).
文摘An accurate measurement of the refractive index is necessary for the optical design of both deep ultraviolet laser diodes and light-emitting diodes. Generally, the refractive indices along different crystallographic axes of anisotropic thin films are measured using variable angle spectroscopic ellipsometry.However, there are still some limitations concerning this method. Here we proposed a potential method to measure the band edge refractive index of wide bandgap semiconductor. An aperiodic oscillation emission phenomenon due to the Fabry-Perot effect was observed in the fluorescence spectrum of an AlN film with a thickness of 1500 nm. Based on the characteristics of the fluorescence spectrum and the definition of Fabry-Perot effect, we obtained the ordinary refractive index of the AlN thin film near the band edge directly. This refractive index measurement method is a supplement to the variable angle ellipsometry,and it is a more direct and effective method for transferred film and thinner samples to measure the fluorescence spectrum.
基金the National Natural Science Foundation of China(51873158,51573141,91833304 and 91433201)the National Key R&D Program of China(2016YFB0401002)+4 种基金Shenzhen Science and Technolgy Program(KQTD20170330110107046 and JCYJ20190808151209557)the Key Technological Innovation Program of Hubei Province(2018AAA013)the Natural Science Foundation for Distinguished Young Scholars of Hubei Province(2017CFA033)the support from the Ministry of Science and Technology of Taiwan(MOST 107-2221-E-002-160-MY3 and 108-2221-E-002-148-MY3)the post-doctoral fellowship from the Ministry of Education(MOE)of Taiwan。
文摘How to control the dipole orientation of organic emitters is a challenge in the field of organic light-emitting diodes(OLEDs).Herein,a linear thermally activated delayed fluorescence(TADF)molecule,PhNAI-PMSBA,bearing a 1,8-naphthalimide-acridine framework was designed by a doublesite long-axis extension strategy to actively control the dipole orientation.The horizontal ratio of emitting dipole orientation of PhNAI-PMSBA reaches 95%,substantially higher than that of isotropic emitters(67%).This unique feature is associated with the intrinsically horizontal molecular orientation of PhNAI-PMSBA and the good agreement between its transition dipole moment direction and molecular long axis.The PhNAI-PMSBA-based OLED achieves an ultrahigh optical outcoupling efficiency of 43.2%and thus affords one of the highest red electroluminescence with an external quantum efficiency of 22.3%and the Commission International de l’Eclairage 1931 coordinates at around(0.60,0.40).
基金financial support to this study by the National Natural Science Foundation of China (21076188, 20836008, 20976158, 20990221and 21076189)the Key Innovation Team for Science and Technology of Zhejiang Province of China (2009R50047)
文摘Titanium dioxide (TiO2) thin films were grown onto Indium tin oxide (ITO) glass under atmospheric pressure by chemical va- por deposition (AP-MOCVD) using titanium tetraisopropoxide astitanium precursor. The as-prepared TiOe/ITO films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and photoelectrochemical measurements. Their photocatalytic (PC) and photoelec- trocatalytic (PEC) activities were evaluated based on the results of methyl orange dye (MO) degradation experiments in aque- ous solution. The difference between the front side (EE, electrolyte/electrode interface) and the back side (SE, sub- strate/electrode interface) illumination was evaluated in both photocurrent and MO degradation experiments. The effect of the film thickness on degradation rate by PEC under the two illumination directions was also studied. Stability of TiO2/ITO film electrode was investigated in repetitive degradation experiments. Overall, the TiO2/ITO film with thickness ranging from 321 to1440 nm deposited by MOCVD method is an effective photoelectrode for MO degradation under SE illumination in PEC reaction system.
基金supported by the National Natural Science Foundation of China (Nos.20903073 and 20671070)the Key Project of Education Ministry of China (No.207008)+1 种基金the Natural Science Foundation of Tianjin (No.09JCYBJC07000)the Science and Technology Developing Foundation for Tianjin Universities (No.20080309)
文摘SnO2 nanosheet films about 200 nm in thickness are successfully fabricated on fluorine-doped tin oxide (FTO) glass by a facile solution-grown approach. The prepared SnO2 nanosheet film is appfied as an interfacial layer between the nanocrystalline TiO2 film and the FTO substrate in dye-sensitized solar cells (DSCs). Experimental results show that the introduction of a SnO2 nanosheet film not only suppresses the electron back-transport reaction at the electrolyte/FTO interface but also provides an efficient electron transition channel along the SnO2 nanosheets, and as a result, increasing the open circuit voltage and short current density, and finally improving the conversion efficiency for the DSCs from 3.89% to 4.62%.
基金supported by the National Basic Research Program of China (Grant Nos. 2009CB623304 and 2011CB013805the National Natural Science Foundation of China (Grant Nos. 51072214 and 51002174)
文摘ZnO-TiO2 hybrid photoanodes were fabricated via the doctor-blade method by integrating vertically-grown sparse ZnO arrays with hydrothermal TiO2 nanoparticles. A special surface-coating technique was developed to deposit a thin TiO2 layer on the surface of ZnO rods. Microstructure, optical and photoelectrochemical performance of the hybrid photoanodes were investigated. The denser ZnO array exhibited bad filling behavior of nanoparticles in the interspace of ZnO rods, strong scattering and low conversion efficiency (0.27%). The sparser array showed a much better integrated microstructure, improved transmittance and high conversion efficiency (2.68%). The surface modification of ZnO rods by the TiO2 thin layer was found useful in improving the interfacial microstructure between the ZnO rod and the TiO2 bulk film, and the total conversion efficiency of 3.01% was achieved, higher than that of the pure TiO2 nanoparticle cell (2.93%). The increased scattering effects on the incident light, the enhanced electron transportation at TiO2/dye/electrolyte interface, and the inhabited recombination were responsible for this improvement.
基金supported by the National Key Research and Development Program of China (2018YFB1502003)the National Natural Science Foundation of China (21875183)+3 种基金the Natural Science Basic Research Program of Shaanxi Province (2019JCW-10)the National Program for the Support of Top-notch Young Professionalsthe Fundamental Research Funds for the Central UniversitiesThe Youth Innovation Team of Shaanxi Universities
文摘n-Si,believed as a promising photoanode candidate,has suffered from sluggish oxygen evolution reaction(OER)kinetics and poor chemical stability when exposed to aqueous electrolyte.Herein,CoO_(x)/Ni:CoOOH bilayers were successfully deposited on n-Si substrate by atomic layer-deposition(ALD)and photoassisted electrochemical deposition(PED)for stabilizing and catalyzing photoelectrochemical(PEC)water oxidation.In comparison to the n-Si/CoO_(x)photoanode as reference,the prepared n-Si/CoO_(x)/Ni:CoOOH photoanode upon the optimized PED process presents a much improved PEC performance for water splitting,with the onset potential cathodically shifted to~1.03 V vs.reversible hydrogen electrode(RHE)and the photocurrent density much increased to 20 mA cm^(−2)at 1.23 V vs.RHE.It is revealed that the introduction of Ni dopants increases the work functions of the deposited Ni:CoOOH overlayers,which gives rise to the upward band bending weakened at the n-Si/CoO_(x)/Ni:CoOOH cascading interface while strengthened at the Ni:CoOOH/electrolyte interface(with the band bending shifted from downward to upward),contributing to the decreased and the increased driving forces for charge transfer at the interfaces,respectively.Then,the balanced driving forces at the interfaces would endow the n-Si/CoO_(x)/Ni:CoOOH photoanode with the best PEC performance.Moreover,PED has been evidenced superior to ED to dope Ni into CoOOH with the formed overlayer effectively catalyzing and stabilizing PEC water splitting.