A Eu^3+-doped CaCO3 phosphor with red emission was prepared by microwave synthesis. The scanning electron microscopy (SEM) image and laser particle size analysis show that the CaCO3:Eu^3+ particles are needle-lik...A Eu^3+-doped CaCO3 phosphor with red emission was prepared by microwave synthesis. The scanning electron microscopy (SEM) image and laser particle size analysis show that the CaCO3:Eu^3+ particles are needle-like in the length range of 5.0-10.0 μm. The results of X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy indicate that pure aragonite CaCO3:Eu^3+ is prepared using microwave irradiation and the Eu^3+ ion as a luminescence center inhabits the site of Ca^2+. The photoluminescence excitation (PLE) spectrum shows that the strong broad band at around 270 nm and weak sharp lines in 300-550 nm are assigned to the charge transfer band of Eu^3+-O^2- and intra-configurational 4f-4f transitions of Eu^3+, respectively. The photoluminescence (PL) spectrum implies that the red luminescence can be attributed to the transitions from the ^5D0 excited level to the ^7FJ (J = 0, 1, 2, 3, 4) levels of Eu^3+ ions with the mainly electric dipole transition ^5D0 → ^7F2 (614 and 620 nm), and the Eu^3+ ions prefer to occupy the low symmetric site in the crystal lattice.展开更多
The development of an efficient artificial H_(2)O_(2) photosynthesis system is a challenging work using H_(2)O and O_(2) as starting materials.Herein,3D In_(2.77)S_(4) nanoflower precursor was in-situ deposited on K^(...The development of an efficient artificial H_(2)O_(2) photosynthesis system is a challenging work using H_(2)O and O_(2) as starting materials.Herein,3D In_(2.77)S_(4) nanoflower precursor was in-situ deposited on K^(+)-doped g-C_(3)N_(4)(KCN)nanosheets using a solvothermal method,then In_(2.77)S_(4)/KCN(IS/KCN)het-erojunction with an intimate interface was obtained after a calcination process.The investigation shows that the photocatalytic H_(2)O_(2) production rate of 50IS/KCN can reach up to 1.36 mmol g^(-1)h^(-1)without any sacrificial reagents under visible light irradiation,which is 9.2 times and 4.1 times higher than that of KCN and In_(2.77)S_(4)/respectively.The enhanced activity of the above composite can be mainly attributed to the S-scheme charge transfer route between KCN and In_(2.77)S_(4) according to density functional theory calculations,electron paramagnetic resonance and free radical capture tests,leading to an expanded light response range and rapid charge separation at their interface,as well as preserving the active electrons and holes for H_(2)O_(2) production.Besides,the unique 3D nanostructure and surface hydrophobicity of IS/KCN facilitate the diffusion and transportation of O_(2) around the active centers,the energy barriers of O_(2) protonation and H_(2)O_(2) desorption steps are ef-fectively reduced over the composite.In addition,this system also exhibits excellent light harvesting ability and stability.This work provides a potential strategy to explore a sustainable H_(2)O_(2) photo-synthesis pathway through the design of heterojunctions with intimate interfaces and desired reac-tion thermodynamics and kinetics.展开更多
This study delves into the charge transfer mechanism of boron (B)-doped 3C-SiC through first-principles investigations. We explore the effects of B doping on the electronic properties of 3C-SiC, focusing on a 12.5% im...This study delves into the charge transfer mechanism of boron (B)-doped 3C-SiC through first-principles investigations. We explore the effects of B doping on the electronic properties of 3C-SiC, focusing on a 12.5% impurity concentration. Our comprehensive analysis encompasses structural properties, electronic band structures, and charge density distributions. The optimized lattice constant and band gap energy of 3C-SiC were found to be 4.373 Å and 1.36 eV respectively, which is in agreement with previous research (Bui, 2012;Muchiri et al., 2018). Our results show that B doping narrows the band gap, enhances electrical conductivity, and influences charge transfer interactions. The charge density analysis reveals substantial interactions between B dopants and surrounding carbon atoms. This work not only enhances our understanding of the material’s electronic properties, but also highlights the importance of charge density analysis for characterizing charge transfer mechanisms and their implications in the 3C-SiC semiconductors.展开更多
Eu3+-doped ZnMoO4 with different doping concentrations were synthesized by a hydrothermal method. The effects of Eu3+ doping on the phase structure and photoluminescence (PL) properties of ZnMoO4 were investigated...Eu3+-doped ZnMoO4 with different doping concentrations were synthesized by a hydrothermal method. The effects of Eu3+ doping on the phase structure and photoluminescence (PL) properties of ZnMoO4 were investigated. The result showed that the introduction of Eu3~ could lead to phase transition of ZnMoO4. With the increase of Eu3-- doping amount, [3-ZnMoO4 was transformed to ct phase gradually, which led to different photoluminescence performances. The optimized doping concentration of Eu3+ was 6 mol% for the highest emission intensity at 615 nm. Its CIE chromaticity coordinates were (0.667, 0.331), which were very close to the values of standard chromaticity (0.67, 0.33) for National Television Standards Committee (NTSC) system. Therefore, Eu3+-doped ZnMoO4 is considered to be a promising red-emitting phosphor for white LED applications.展开更多
The photoluminescence (PL) characteristics of Eu^3+ and Li^+ co-doped ZnO PL materials against heat-treatment temperature were discussed. The PL xerogel and powder samples were prepared by solgel process. The emis...The photoluminescence (PL) characteristics of Eu^3+ and Li^+ co-doped ZnO PL materials against heat-treatment temperature were discussed. The PL xerogel and powder samples were prepared by solgel process. The emission spectra of all samples showed two broad bands peaking at 590 nm and 620 nm under UV-Vis excitation. But the relative intensity of red PL (620 nm) was much greater than that of green PL (590 nm) of the same sample, that s to say, the red color was the main luminescence. With heat-treatment temperature increase, the two kinds of colors PL intensity decreased, and both the red and green PL intensity of the xerogel samples was much greater than those of powder samples respectively. The XRD patterns revealed that Eu^3+ ions were successfully incorporated in ZnO crystals in xerogel samples. When heat-treatment temperature reached 350 ℃, the Eu^3+ began to separate out of the ZnO crystals and Eu2O3 crystals came into being. When the powder sample was subjected to UV-Vis excitation, the energy transfered from the host ZnO emission to Eu^3+ became weaker than the xerogel sample.展开更多
Single phase of BaGd0.9-xMxEu0.1B9O16(M=Al or Sc, 0≤x≤0.3) powder was prepared by the solid-state reaction and its photoluminescence(PL) properties were investigated under ultraviolet(UV) and vacuum ultraviole...Single phase of BaGd0.9-xMxEu0.1B9O16(M=Al or Sc, 0≤x≤0.3) powder was prepared by the solid-state reaction and its photoluminescence(PL) properties were investigated under ultraviolet(UV) and vacuum ultraviolet(VUV) excitation.Monitored with 613 nm emission, the excitation spectra of BaGd0.9-xMxEu0.1B9O16 consisted of three broad bands peaking at about 242, 208, and 142 nm, respectively.The one at about 242 nm originated from the charge transfer band(CTB) of O2-→Eu^3+.The other two were assigned to the absorption of the host, which was overlapped with absorptions among borate groups, f→d transition of RE3+(RE=Gd, Eu), and the charge transfer transition of O2-→Gd^3+.The maximum emission peak was observed at about 613 nm in the emission spectra of BaGd0.9-xMxEu0.1B9O16 under both 254 and 147 nm excitation, which originated from the electric dipole 5D0→7F2 transition of Eu^3+.When excited with 254 nm, the integral emission intensity of Eu^3+ increased after Al^3+ or Sc^3+ substituting Gd^3+ partly in BaGd0.9Eu0.1B9O16.Under 147 nm excitation, the integral emission intensity of Eu^3+ decreased after some Gd^3+ was replaced by Sc^3+, but increased after adding appropriate Al^3+ into BaGd0.9Eu0.1B9O16.展开更多
Al-doped and B, Al-codoped silica xerogel was fabricated by sol-gel process. The influence of B ions and annealing temperature on luminescent properties of phosphors were studied by using fluorescence spectrum, X-ray ...Al-doped and B, Al-codoped silica xerogel was fabricated by sol-gel process. The influence of B ions and annealing temperature on luminescent properties of phosphors were studied by using fluorescence spectrum, X-ray diffraction, DSC, TG/DTG analysis and IR spectrum. The heat treatment has a large effect on the luminescent properties. Under 248 nm excitation, the emission spectrum of samples heated shows characteristic emission peaks of Eu^3+ ions are, which are due to the transitions of ^5D0→^7FJ(J = 0, 1, 2, 3, 4) of Eu^3+ , respectively. The transition of ^5D0→^7F1 is split into two peaks.展开更多
A series of SrIn2 O4 :Eu^3+ phosphors are synthesized by a high temperature solid-state method, and their luminescent properties are investigated. They can be excited by 395-nm radiation, and produce red emission (...A series of SrIn2 O4 :Eu^3+ phosphors are synthesized by a high temperature solid-state method, and their luminescent properties are investigated. They can be excited by 395-nm radiation, and produce red emission (619 nm); however, they have a low absorption of near-ultraviolet light with the wavelength of 400nm–405 nm. When co-doped with A^+ (A=Li, Na, K), the emission intensity of SrIn2O4 :Eu^3+ is significantly enhanced, but its emission and excitation spectral profile is unchanged. With co-doping Sm^3+ , not only is the emission intensity of SrIn2 O4 :Eu^3+ enhanced, but also the absorption is broadened and strengthened in the range of 400 nm–405nm. The effect of Sm^3+ -doped content on the emission intensity of SrIn2O4 :Eu^3+ , Sm^3+ is investigated, and the optimal Sm^3+ content is 0.02 mol.展开更多
By using a whitelight lamp, an Ar+ ion laser whosewavelength was tuned to 457. 9 nmand a tunable Rh 6G dye laser(linewidth: 0. 5 cm-1) pumped bythe second harmonic of a Nd: YAGlaser as light sources and using amonochr...By using a whitelight lamp, an Ar+ ion laser whosewavelength was tuned to 457. 9 nmand a tunable Rh 6G dye laser(linewidth: 0. 5 cm-1) pumped bythe second harmonic of a Nd: YAGlaser as light sources and using amonochromator, a phase-lockingamplifier and a computer as the data detecting system, the transmission spectrum, fluorescence spectra, excitation spectrum and siteselective fluorescence spectra ofthe Eu3+: Y2SiO5 crystal were observed. More than thirty out of thetotal fifty spectral lines were observed for 5D0→7F0,1,2,3,4 transitions. The Eu3+ ions occupy twokinds of the Y3+ sites with the lowsymmetry in this crystal. The difference of the wavelengths of thetwo Eu3+ sites for 7F0→5D0 transition is about 0. 2 nm. It was foundthat the two sites were nonequivalent optical ones at room temperature. Crystal lattice constants a,b, c, and β of Eu3+: Y2SiO5 werealso measured by the X-ray diffraction method. The results show thatthe lattice constants a, b, and cof the crystal doped Eu3+ ions isvery close to those of the Y2SiO5crystal undoped Eu3+ ions.展开更多
By using an improved Bridgman method,0.3 mol%Tm^(3+)/0.6 mol%Tb^(3+)/y mol%Eu^(3+)(y=0,0.4,0.6,0.8)doped Na_(5)Y_(9)F_(32)single crystals were prepared.The x-ray diffraction,excitation spectra,emission spectra and flu...By using an improved Bridgman method,0.3 mol%Tm^(3+)/0.6 mol%Tb^(3+)/y mol%Eu^(3+)(y=0,0.4,0.6,0.8)doped Na_(5)Y_(9)F_(32)single crystals were prepared.The x-ray diffraction,excitation spectra,emission spectra and fluorescence decay curves were used to explore the crystal structure and optical performance of the obtained samples.When excited by 362 nm light,the cool white emission was realized by Na_(5)Y_(9)F_(32)single crystal triply-doped with 0.3 mol%Tm^(3+)/0.6 mol%Tb^(3+)/0.8 mol%Eu^(3+),in which the Commission Internationale de l’Eclairage(CIE)chromaticity coordinate was(0.2995,0.3298)and the correlated color temperature(CCT)was 6586 K.The integrated normalized emission intensity of the tridoped single crystal at 448 K could keep 62%of that at 298 K.The internal quantum yield(QY)was calculated to be~15.16%by integrating spheres.These results suggested that the single crystals tri-doped with Tm^(3+),Tb^(3+)and Eu^(3+)ions have a promising potential application for white light-emitting diodes(w-LEDs).展开更多
Ho^3+-doped titanium dioxide(TiO2:Ho^3+) downconversion(DC) nanowires were synthesized through a simple hydrothermal method followed by a subsequent calcination process after being immersed in Ho(NO3)3 aqueou...Ho^3+-doped titanium dioxide(TiO2:Ho^3+) downconversion(DC) nanowires were synthesized through a simple hydrothermal method followed by a subsequent calcination process after being immersed in Ho(NO3)3 aqueous solution. Moreover, TiO2:Ho^3+ nanowires(HTNWs) were used as the photoanode in dye-sensitized solar cells(DSSCs) to investigate their photoelectric properties. Scanning electron microscopy(SEM) and X-ray diffraction(XRD) were used to characterize the morphology and structure of the material, respectively. The photofluorescence and ultraviolet-visible absorption spectra of HTNWs reveal a DC from the near and middle ultraviolet light to visible light which matches the strong absorbed region of the N719 dye. Compared with the pure TNW photoanode, HTNWs DC photoanodes show greater photovoltaic efficiency. The photovoltaic conversion efficiency(η) of the DSSCs with HTNWs photoanode doped with 4% Ho2O3(mass fraction) is two times that with pure TNW photoanode. This enhancement could be attributed to HTNWs which could extend the spectral response range of DSSCs to the near and middle ultraviolet region and increase the short-circuit current density(Jsc) of DSSCs, thus leading to the enhancement of photovoltaic conversion efficiency.展开更多
基金supported by the National Natural Science Foundation of China (No. 10476024) the Science and Technology Bureau of Sichuan Province, China (No. 2006J13-059)
文摘A Eu^3+-doped CaCO3 phosphor with red emission was prepared by microwave synthesis. The scanning electron microscopy (SEM) image and laser particle size analysis show that the CaCO3:Eu^3+ particles are needle-like in the length range of 5.0-10.0 μm. The results of X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy indicate that pure aragonite CaCO3:Eu^3+ is prepared using microwave irradiation and the Eu^3+ ion as a luminescence center inhabits the site of Ca^2+. The photoluminescence excitation (PLE) spectrum shows that the strong broad band at around 270 nm and weak sharp lines in 300-550 nm are assigned to the charge transfer band of Eu^3+-O^2- and intra-configurational 4f-4f transitions of Eu^3+, respectively. The photoluminescence (PL) spectrum implies that the red luminescence can be attributed to the transitions from the ^5D0 excited level to the ^7FJ (J = 0, 1, 2, 3, 4) levels of Eu^3+ ions with the mainly electric dipole transition ^5D0 → ^7F2 (614 and 620 nm), and the Eu^3+ ions prefer to occupy the low symmetric site in the crystal lattice.
文摘The development of an efficient artificial H_(2)O_(2) photosynthesis system is a challenging work using H_(2)O and O_(2) as starting materials.Herein,3D In_(2.77)S_(4) nanoflower precursor was in-situ deposited on K^(+)-doped g-C_(3)N_(4)(KCN)nanosheets using a solvothermal method,then In_(2.77)S_(4)/KCN(IS/KCN)het-erojunction with an intimate interface was obtained after a calcination process.The investigation shows that the photocatalytic H_(2)O_(2) production rate of 50IS/KCN can reach up to 1.36 mmol g^(-1)h^(-1)without any sacrificial reagents under visible light irradiation,which is 9.2 times and 4.1 times higher than that of KCN and In_(2.77)S_(4)/respectively.The enhanced activity of the above composite can be mainly attributed to the S-scheme charge transfer route between KCN and In_(2.77)S_(4) according to density functional theory calculations,electron paramagnetic resonance and free radical capture tests,leading to an expanded light response range and rapid charge separation at their interface,as well as preserving the active electrons and holes for H_(2)O_(2) production.Besides,the unique 3D nanostructure and surface hydrophobicity of IS/KCN facilitate the diffusion and transportation of O_(2) around the active centers,the energy barriers of O_(2) protonation and H_(2)O_(2) desorption steps are ef-fectively reduced over the composite.In addition,this system also exhibits excellent light harvesting ability and stability.This work provides a potential strategy to explore a sustainable H_(2)O_(2) photo-synthesis pathway through the design of heterojunctions with intimate interfaces and desired reac-tion thermodynamics and kinetics.
文摘This study delves into the charge transfer mechanism of boron (B)-doped 3C-SiC through first-principles investigations. We explore the effects of B doping on the electronic properties of 3C-SiC, focusing on a 12.5% impurity concentration. Our comprehensive analysis encompasses structural properties, electronic band structures, and charge density distributions. The optimized lattice constant and band gap energy of 3C-SiC were found to be 4.373 Å and 1.36 eV respectively, which is in agreement with previous research (Bui, 2012;Muchiri et al., 2018). Our results show that B doping narrows the band gap, enhances electrical conductivity, and influences charge transfer interactions. The charge density analysis reveals substantial interactions between B dopants and surrounding carbon atoms. This work not only enhances our understanding of the material’s electronic properties, but also highlights the importance of charge density analysis for characterizing charge transfer mechanisms and their implications in the 3C-SiC semiconductors.
文摘Eu3+-doped ZnMoO4 with different doping concentrations were synthesized by a hydrothermal method. The effects of Eu3+ doping on the phase structure and photoluminescence (PL) properties of ZnMoO4 were investigated. The result showed that the introduction of Eu3~ could lead to phase transition of ZnMoO4. With the increase of Eu3-- doping amount, [3-ZnMoO4 was transformed to ct phase gradually, which led to different photoluminescence performances. The optimized doping concentration of Eu3+ was 6 mol% for the highest emission intensity at 615 nm. Its CIE chromaticity coordinates were (0.667, 0.331), which were very close to the values of standard chromaticity (0.67, 0.33) for National Television Standards Committee (NTSC) system. Therefore, Eu3+-doped ZnMoO4 is considered to be a promising red-emitting phosphor for white LED applications.
基金the National Defense Foundation Research Item of China(No.K 1203061109)
文摘The photoluminescence (PL) characteristics of Eu^3+ and Li^+ co-doped ZnO PL materials against heat-treatment temperature were discussed. The PL xerogel and powder samples were prepared by solgel process. The emission spectra of all samples showed two broad bands peaking at 590 nm and 620 nm under UV-Vis excitation. But the relative intensity of red PL (620 nm) was much greater than that of green PL (590 nm) of the same sample, that s to say, the red color was the main luminescence. With heat-treatment temperature increase, the two kinds of colors PL intensity decreased, and both the red and green PL intensity of the xerogel samples was much greater than those of powder samples respectively. The XRD patterns revealed that Eu^3+ ions were successfully incorporated in ZnO crystals in xerogel samples. When heat-treatment temperature reached 350 ℃, the Eu^3+ began to separate out of the ZnO crystals and Eu2O3 crystals came into being. When the powder sample was subjected to UV-Vis excitation, the energy transfered from the host ZnO emission to Eu^3+ became weaker than the xerogel sample.
基金supported by the Science Program of the Education Office, Jiangxi Province (GJJ08345)the Young Foundation of Jiangxi Univer-sity of Finance and Economy
文摘Single phase of BaGd0.9-xMxEu0.1B9O16(M=Al or Sc, 0≤x≤0.3) powder was prepared by the solid-state reaction and its photoluminescence(PL) properties were investigated under ultraviolet(UV) and vacuum ultraviolet(VUV) excitation.Monitored with 613 nm emission, the excitation spectra of BaGd0.9-xMxEu0.1B9O16 consisted of three broad bands peaking at about 242, 208, and 142 nm, respectively.The one at about 242 nm originated from the charge transfer band(CTB) of O2-→Eu^3+.The other two were assigned to the absorption of the host, which was overlapped with absorptions among borate groups, f→d transition of RE3+(RE=Gd, Eu), and the charge transfer transition of O2-→Gd^3+.The maximum emission peak was observed at about 613 nm in the emission spectra of BaGd0.9-xMxEu0.1B9O16 under both 254 and 147 nm excitation, which originated from the electric dipole 5D0→7F2 transition of Eu^3+.When excited with 254 nm, the integral emission intensity of Eu^3+ increased after Al^3+ or Sc^3+ substituting Gd^3+ partly in BaGd0.9Eu0.1B9O16.Under 147 nm excitation, the integral emission intensity of Eu^3+ decreased after some Gd^3+ was replaced by Sc^3+, but increased after adding appropriate Al^3+ into BaGd0.9Eu0.1B9O16.
文摘Al-doped and B, Al-codoped silica xerogel was fabricated by sol-gel process. The influence of B ions and annealing temperature on luminescent properties of phosphors were studied by using fluorescence spectrum, X-ray diffraction, DSC, TG/DTG analysis and IR spectrum. The heat treatment has a large effect on the luminescent properties. Under 248 nm excitation, the emission spectrum of samples heated shows characteristic emission peaks of Eu^3+ ions are, which are due to the transitions of ^5D0→^7FJ(J = 0, 1, 2, 3, 4) of Eu^3+ , respectively. The transition of ^5D0→^7F1 is split into two peaks.
基金Project supported by the National Natural Science Foundation of China (Grant No. 50902042)the Natural Science Foundation of Hebei Province, China(Grant Nos. E2009000209 and E2010000283)+1 种基金the Education Bureau Foundation of Hebei Province, China (Grant No. 2009313)the Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Ministry of Education, China (Grant No. 2010LOI12)
文摘A series of SrIn2 O4 :Eu^3+ phosphors are synthesized by a high temperature solid-state method, and their luminescent properties are investigated. They can be excited by 395-nm radiation, and produce red emission (619 nm); however, they have a low absorption of near-ultraviolet light with the wavelength of 400nm–405 nm. When co-doped with A^+ (A=Li, Na, K), the emission intensity of SrIn2O4 :Eu^3+ is significantly enhanced, but its emission and excitation spectral profile is unchanged. With co-doping Sm^3+ , not only is the emission intensity of SrIn2 O4 :Eu^3+ enhanced, but also the absorption is broadened and strengthened in the range of 400 nm–405nm. The effect of Sm^3+ -doped content on the emission intensity of SrIn2O4 :Eu^3+ , Sm^3+ is investigated, and the optimal Sm^3+ content is 0.02 mol.
文摘By using a whitelight lamp, an Ar+ ion laser whosewavelength was tuned to 457. 9 nmand a tunable Rh 6G dye laser(linewidth: 0. 5 cm-1) pumped bythe second harmonic of a Nd: YAGlaser as light sources and using amonochromator, a phase-lockingamplifier and a computer as the data detecting system, the transmission spectrum, fluorescence spectra, excitation spectrum and siteselective fluorescence spectra ofthe Eu3+: Y2SiO5 crystal were observed. More than thirty out of thetotal fifty spectral lines were observed for 5D0→7F0,1,2,3,4 transitions. The Eu3+ ions occupy twokinds of the Y3+ sites with the lowsymmetry in this crystal. The difference of the wavelengths of thetwo Eu3+ sites for 7F0→5D0 transition is about 0. 2 nm. It was foundthat the two sites were nonequivalent optical ones at room temperature. Crystal lattice constants a,b, c, and β of Eu3+: Y2SiO5 werealso measured by the X-ray diffraction method. The results show thatthe lattice constants a, b, and cof the crystal doped Eu3+ ions isvery close to those of the Y2SiO5crystal undoped Eu3+ ions.
基金Project supported by the National Natural Science Foundation of China(Grant No.62275133)the Natural Science Foundation of Zhejiang Province of China(Grant No.LY22E020002)+1 种基金the Natural Science Foundation of Ningbo(Grant Nos.2021J077 and 202003N4099)K.C.Wong Magna Fund in Ningbo University
文摘By using an improved Bridgman method,0.3 mol%Tm^(3+)/0.6 mol%Tb^(3+)/y mol%Eu^(3+)(y=0,0.4,0.6,0.8)doped Na_(5)Y_(9)F_(32)single crystals were prepared.The x-ray diffraction,excitation spectra,emission spectra and fluorescence decay curves were used to explore the crystal structure and optical performance of the obtained samples.When excited by 362 nm light,the cool white emission was realized by Na_(5)Y_(9)F_(32)single crystal triply-doped with 0.3 mol%Tm^(3+)/0.6 mol%Tb^(3+)/0.8 mol%Eu^(3+),in which the Commission Internationale de l’Eclairage(CIE)chromaticity coordinate was(0.2995,0.3298)and the correlated color temperature(CCT)was 6586 K.The integrated normalized emission intensity of the tridoped single crystal at 448 K could keep 62%of that at 298 K.The internal quantum yield(QY)was calculated to be~15.16%by integrating spheres.These results suggested that the single crystals tri-doped with Tm^(3+),Tb^(3+)and Eu^(3+)ions have a promising potential application for white light-emitting diodes(w-LEDs).
基金Project(2012FU125X03)supported by Open Research Fund Project of National Engineering Research Center of SeafoodChina+3 种基金Project(2011–191)supported by the Key Science and Technology Platform of Liaoning Provincial Education DepartmentChinaProject(2010–354)supported by the Science and Technology Platform of DalianChina
文摘Ho^3+-doped titanium dioxide(TiO2:Ho^3+) downconversion(DC) nanowires were synthesized through a simple hydrothermal method followed by a subsequent calcination process after being immersed in Ho(NO3)3 aqueous solution. Moreover, TiO2:Ho^3+ nanowires(HTNWs) were used as the photoanode in dye-sensitized solar cells(DSSCs) to investigate their photoelectric properties. Scanning electron microscopy(SEM) and X-ray diffraction(XRD) were used to characterize the morphology and structure of the material, respectively. The photofluorescence and ultraviolet-visible absorption spectra of HTNWs reveal a DC from the near and middle ultraviolet light to visible light which matches the strong absorbed region of the N719 dye. Compared with the pure TNW photoanode, HTNWs DC photoanodes show greater photovoltaic efficiency. The photovoltaic conversion efficiency(η) of the DSSCs with HTNWs photoanode doped with 4% Ho2O3(mass fraction) is two times that with pure TNW photoanode. This enhancement could be attributed to HTNWs which could extend the spectral response range of DSSCs to the near and middle ultraviolet region and increase the short-circuit current density(Jsc) of DSSCs, thus leading to the enhancement of photovoltaic conversion efficiency.