A set of co-doped(Tb^(3+)/Dy^(3+))lithium zinc borate(LZB)glasses were developed by melt quenching.The structural evaluation was performed for synthesized glassy matrices.The Dy^(3+)and Tb^(3+)individually doped glass...A set of co-doped(Tb^(3+)/Dy^(3+))lithium zinc borate(LZB)glasses were developed by melt quenching.The structural evaluation was performed for synthesized glassy matrices.The Dy^(3+)and Tb^(3+)individually doped glasses exhibit intense yellow and green luminescence bands at 575 nm(^(4)F_(9/2)→^(6)H_(13/2))and543 nm(^(5)D_(4)→^(7)F_(5)),respectively.The sensitization effect of Dy^(3+)on Tb^(3+)was analyzed by increasing the Tb^(3+)content with respect to the optimum Dy^(3+)content(0.5 mol%)in Dy^(3+)/Tb^(3+).The spectral overlay of Dy^(3+)luminescence and Tb^(3+)absorption profiles,Dy^(3+)/Tb^(3+)PL spectra under different excitations 352,362,376,and 385 nm,shortening decay lifetimes of Dy^(3+)in Dy^(3+)/Tb^(3+)co-activated glasses,energy transfer(ET)parameters,chromaticity coordinates and their corresponding correlated temperatures all help to explain ET from Dy^(3+)to Tb^(3+).At 385 nm of Dy^(3+)excitation,the optimized co-activated(0.5Dy^(3+)+1.0Tb^(3+)):LZB glass displays cool white light emission.The non-radiative ET from Dy^(3+)to Tb^(3+)is dominated by electric dipole-dipole interaction and its ET efficiency was calculated to be 63%.At the same time,reverse ET from Tb^(3+)to Dy^(3+)was also analyzed.The shift in color coordinates from dominant yellow to greenish-yellow,green and white light emission suggests that Dy^(3+)/Tb^(3+)coactivated LZB glasses can be a potential candidate for UV converted multicolor and white light emitting devices.展开更多
The spectroscopic properties of a series of Dy^(3+)single-doped and Dy^(3+)/Nd^(3+),Dy^(3+)/Tb^(3+),and Dy^(3+)/Tm^(3+)co-doped YAlO_(3)(yttrium aluminum perovskite,YAP)phosphors were investigated and compared through...The spectroscopic properties of a series of Dy^(3+)single-doped and Dy^(3+)/Nd^(3+),Dy^(3+)/Tb^(3+),and Dy^(3+)/Tm^(3+)co-doped YAlO_(3)(yttrium aluminum perovskite,YAP)phosphors were investigated and compared through the measurements of optical absorption,emission spectra,and fluorescence decay curves.For the Dy^(3+)ion single-doped samples,the intensity of each absorption band increases with an increment in Dy^(3+)ion doping concentration,and the identified strong absorption peak at 447 nm indicates that Dy^(3+):YAP phosphors are suitable to be pumped by a blue laser diode(LD).For all co-doped samples,absorption peaks of Dy^(3+)ion along with some of the absorption bands of Nd^(3+),Tb^(3+),and Tm^(3+)ions are observed.Under 351 and 447 nm excitation,a prominent emission peak at 572 nm was obtained in all the samples,corresponding to Dy^(3+):^(4)F_(9/2)→^(6)H_(13/2)transition.Here,2 at%Dy^(3+):YAP phosphor exhibits the highest yellow emission intensity under 447 nm pumping.Among the three kinds of Dy^(3+)co-doped phosphors,Dy^(3+)/Tb^(3+):YAP phosphor possesses the dominant yellow emission.The fluorescence decay curves show exponential behaviour and are fitted well.The Commission International de L’Eclairage(CIE)chromaticity coordinates were calculated following the respective emission spectra,and it is found that all the coordinates locate in the yellow region.The energy transfer(ET)processes were investigated and the concentration quenching mechanism was discussed.The obtained results suggest that Dy^(3+)-activated YAP phosphors are good candidates for yellow LED applications.展开更多
Spherically shaped mesoporous silica nanoparticles （MSNs） having honeycomb like porous structure were synthesized by sol-gel method. Transmission electron microscopy （TEM）, surface area measurement and X-ray diffr...Spherically shaped mesoporous silica nanoparticles （MSNs） having honeycomb like porous structure were synthesized by sol-gel method. Transmission electron microscopy （TEM）, surface area measurement and X-ray diffractometry were used, revealing the hexagonal shaped pores in MSNs. MSNs with surface area of 1104.47 m^2/g and large porosity of 2.8 nm in pore diameter and 0.87 cm^3/g in pore volume were synthesized. TEM images showed spherical nanoparticles of - 200-300 nm having honeycomb like pores. Stilbene 420 laser dye was incorporated in MSNs and photoluminescence spectra of stilbene 420 in MSNs and in ethanol had been studied. Stilbene 420 laser dye showed high fluorescence intensity in the fluorescence spectra of MSNs than that of ethanol. The prolonged fluorescence lifetime decay of stilbene in MSNs and the increase in fluorescence intensity for stilbene 420 in MSNs would make these nanomaterials more useful for nanosensors and nanolasers application.展开更多
<span style="font-family:Verdana;">This manuscript presents a simple method for excess minority carriers’ lifetime measurement</span><span style="font-family:""> </span&g...<span style="font-family:Verdana;">This manuscript presents a simple method for excess minority carriers’ lifetime measurement</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">within the base region of p-n junction polycrystalline solar </span><span style="font-family:Verdana;">cell</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">in transient mode.</span><span style="font-family:""> </span><span style="font-family:Verdana;">This work is an experimental transient</span><span style="font-family:Verdana;"> 3-Dimensionnal study.</span><span style="font-family:""> </span><span style="font-family:Verdana;">The magnitude of the magnetic field B is varied from 0 mT to 0.045 mT. Indeed, the solar cell is illuminated by a stroboscopic flash with air mass 1.5</span><span style="font-family:""> </span><span style="font-family:Verdana;">and under magnetic field in transient state.</span><span style="font-family:""> </span><span style="font-family:Verdana;">The experimental details are assumed in a figure. The procedure is outlined by the Open Circuit Voltage Decay analysis. Effective minority carrier life-time is calculated by fitting the linear zone of the transient voltage decay curve</span><span style="font-family:""> </span><span style="font-family:Verdana;">because linear decay is an ideal decay. The kaleidagraph software permits access to the slope of the curve which is inversely proportional to the</span><span style="font-family:""> </span><span style="font-family:Verdana;">lifetime. The external magnetic effects</span><span style="font-family:""> </span><span style="font-family:Verdana;">on minority carriers’ effective lifetime </span><span style="font-family:Verdana;">is</span><span style="font-family:Verdana;"> then</span><span style="font-family:""> </span><span style="font-family:Verdana;">presented and analyzed.</span><span style="font-family:""> </span><span style="font-family:Verdana;">The analysis show</span><span s展开更多
Porphyrins occur in a number of important biomolecules and are also synthetically made for use as probe component of chemical and biological sensors. The performance of dye sensitized solar cells with two different po...Porphyrins occur in a number of important biomolecules and are also synthetically made for use as probe component of chemical and biological sensors. The performance of dye sensitized solar cells with two different porphyrin dyes was investigated in this work. The two porphyrin complexes comprised of a metal-free 5, 10, 15, 20-meso-tetrakis-(9H-2-fluorene-yl) porphyrin (H2TFP) and its Zinc complex (ZnTFP). UV-Vis, Fluorescence, and Fourier transformed infrared measurements of the two dyes were carried out to evaluate their absorption, emission and binding characteristics. Both dyes absorbed light in the UV-visible region all the way to the near-infrared. The surface morphology and elemental analysis of the porphyrin dye sensitized photoanodes were determined using Field Emission Scanning Electron Microscopy Imaging and Transmission Electron Microscopy Imaging. Cyclic voltammetry studies, current-voltage characteristics and the electrochemical impedance spectroscopic studies were also carried out. Solar-to-electric energy efficiency of H2TFP dye sensitized solar cell was higher (0.11%) than that of the zinc complex (0.08%). Thus the metal free porphyrin generated more power than the zinc complex under similar conditions. The impedance measurement also displayed less overall resistance for the free porphyrin (50 Ω) compared with the zinc complex (130 Ω). The LUMO levels of H2TFP and ZnTFP sensitizers were -0.87 eV and -0.77 eV respectively. Both of these LUMO values are higher than the lower bound level of the conduction band of TiO2 (-4.0 eV), ensuring the efficient injection of an electron from the excited porphyrin dye to the conduction band of the titanium dioxide.展开更多
A series of barium-tungstate-based phosphors doped with different concentrations of Dy<sup>3+</sup> were synthesized by solid-state reaction method. Photoluminescence properties and decay lifetime of Dy<...A series of barium-tungstate-based phosphors doped with different concentrations of Dy<sup>3+</sup> were synthesized by solid-state reaction method. Photoluminescence properties and decay lifetime of Dy<sup>3+</sup>-doped BaWO<sub>4</sub> samples were studied. The results indicated that luminescent properties of BaWO<sub>4</sub>:Dy<sup>3+</sup> depended on the Dy<sup>3+</sup> concentration, and the inner energy could transfer from to Dy<sup>3+</sup>. The quality of the light was checked by estimating CIE parameters, and the results showed that BaWO<sub>4</sub>:Dy<sup>3+</sup> was a potential candidate as blue-green luminescent materials in white LED because of its excellent emission spectrum excited by UV light.展开更多
The nanoparticles of a spirooxazine （SPO） and its photomerocyanine （PMC） were prepared through the reprecipitation method. Two distinct features were observed. One is that the decaying lifetime for PMC nanoparticl...The nanoparticles of a spirooxazine （SPO） and its photomerocyanine （PMC） were prepared through the reprecipitation method. Two distinct features were observed. One is that the decaying lifetime for PMC nanoparticles was 600 times of that for the dispersed molecules, and the other is that the fluorescence intensity of SPO nanoparticles was enhanced by 240 times of that of the dispersed monomer.展开更多
基金Project supported by the National Research Foundation of Korea(NRF)grant funded by the Korea Government(MSIT)(2020R1C1C1014787)。
文摘A set of co-doped(Tb^(3+)/Dy^(3+))lithium zinc borate(LZB)glasses were developed by melt quenching.The structural evaluation was performed for synthesized glassy matrices.The Dy^(3+)and Tb^(3+)individually doped glasses exhibit intense yellow and green luminescence bands at 575 nm(^(4)F_(9/2)→^(6)H_(13/2))and543 nm(^(5)D_(4)→^(7)F_(5)),respectively.The sensitization effect of Dy^(3+)on Tb^(3+)was analyzed by increasing the Tb^(3+)content with respect to the optimum Dy^(3+)content(0.5 mol%)in Dy^(3+)/Tb^(3+).The spectral overlay of Dy^(3+)luminescence and Tb^(3+)absorption profiles,Dy^(3+)/Tb^(3+)PL spectra under different excitations 352,362,376,and 385 nm,shortening decay lifetimes of Dy^(3+)in Dy^(3+)/Tb^(3+)co-activated glasses,energy transfer(ET)parameters,chromaticity coordinates and their corresponding correlated temperatures all help to explain ET from Dy^(3+)to Tb^(3+).At 385 nm of Dy^(3+)excitation,the optimized co-activated(0.5Dy^(3+)+1.0Tb^(3+)):LZB glass displays cool white light emission.The non-radiative ET from Dy^(3+)to Tb^(3+)is dominated by electric dipole-dipole interaction and its ET efficiency was calculated to be 63%.At the same time,reverse ET from Tb^(3+)to Dy^(3+)was also analyzed.The shift in color coordinates from dominant yellow to greenish-yellow,green and white light emission suggests that Dy^(3+)/Tb^(3+)coactivated LZB glasses can be a potential candidate for UV converted multicolor and white light emitting devices.
基金Projects supported by the National Natural Science Foundation of China(51872286,51832007,51472240,61675204)Science and Technology Plan Leading Project of Fujian Province(2018H0046)+3 种基金State Key Laboratory of Rare Earth Resource Utilization(RERU2018004,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences)the National Key Research and Development Program of China(2016YFB0701002)the fund of the State Key Laboratory of Solidification Processing(SKLSP201908,Northwestern Polytechnical University)Natural Science Foundation of Jiangxi Province(20181BAB211009)。
文摘The spectroscopic properties of a series of Dy^(3+)single-doped and Dy^(3+)/Nd^(3+),Dy^(3+)/Tb^(3+),and Dy^(3+)/Tm^(3+)co-doped YAlO_(3)(yttrium aluminum perovskite,YAP)phosphors were investigated and compared through the measurements of optical absorption,emission spectra,and fluorescence decay curves.For the Dy^(3+)ion single-doped samples,the intensity of each absorption band increases with an increment in Dy^(3+)ion doping concentration,and the identified strong absorption peak at 447 nm indicates that Dy^(3+):YAP phosphors are suitable to be pumped by a blue laser diode(LD).For all co-doped samples,absorption peaks of Dy^(3+)ion along with some of the absorption bands of Nd^(3+),Tb^(3+),and Tm^(3+)ions are observed.Under 351 and 447 nm excitation,a prominent emission peak at 572 nm was obtained in all the samples,corresponding to Dy^(3+):^(4)F_(9/2)→^(6)H_(13/2)transition.Here,2 at%Dy^(3+):YAP phosphor exhibits the highest yellow emission intensity under 447 nm pumping.Among the three kinds of Dy^(3+)co-doped phosphors,Dy^(3+)/Tb^(3+):YAP phosphor possesses the dominant yellow emission.The fluorescence decay curves show exponential behaviour and are fitted well.The Commission International de L’Eclairage(CIE)chromaticity coordinates were calculated following the respective emission spectra,and it is found that all the coordinates locate in the yellow region.The energy transfer(ET)processes were investigated and the concentration quenching mechanism was discussed.The obtained results suggest that Dy^(3+)-activated YAP phosphors are good candidates for yellow LED applications.
文摘Spherically shaped mesoporous silica nanoparticles （MSNs） having honeycomb like porous structure were synthesized by sol-gel method. Transmission electron microscopy （TEM）, surface area measurement and X-ray diffractometry were used, revealing the hexagonal shaped pores in MSNs. MSNs with surface area of 1104.47 m^2/g and large porosity of 2.8 nm in pore diameter and 0.87 cm^3/g in pore volume were synthesized. TEM images showed spherical nanoparticles of - 200-300 nm having honeycomb like pores. Stilbene 420 laser dye was incorporated in MSNs and photoluminescence spectra of stilbene 420 in MSNs and in ethanol had been studied. Stilbene 420 laser dye showed high fluorescence intensity in the fluorescence spectra of MSNs than that of ethanol. The prolonged fluorescence lifetime decay of stilbene in MSNs and the increase in fluorescence intensity for stilbene 420 in MSNs would make these nanomaterials more useful for nanosensors and nanolasers application.
文摘<span style="font-family:Verdana;">This manuscript presents a simple method for excess minority carriers’ lifetime measurement</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">within the base region of p-n junction polycrystalline solar </span><span style="font-family:Verdana;">cell</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">in transient mode.</span><span style="font-family:""> </span><span style="font-family:Verdana;">This work is an experimental transient</span><span style="font-family:Verdana;"> 3-Dimensionnal study.</span><span style="font-family:""> </span><span style="font-family:Verdana;">The magnitude of the magnetic field B is varied from 0 mT to 0.045 mT. Indeed, the solar cell is illuminated by a stroboscopic flash with air mass 1.5</span><span style="font-family:""> </span><span style="font-family:Verdana;">and under magnetic field in transient state.</span><span style="font-family:""> </span><span style="font-family:Verdana;">The experimental details are assumed in a figure. The procedure is outlined by the Open Circuit Voltage Decay analysis. Effective minority carrier life-time is calculated by fitting the linear zone of the transient voltage decay curve</span><span style="font-family:""> </span><span style="font-family:Verdana;">because linear decay is an ideal decay. The kaleidagraph software permits access to the slope of the curve which is inversely proportional to the</span><span style="font-family:""> </span><span style="font-family:Verdana;">lifetime. The external magnetic effects</span><span style="font-family:""> </span><span style="font-family:Verdana;">on minority carriers’ effective lifetime </span><span style="font-family:Verdana;">is</span><span style="font-family:Verdana;"> then</span><span style="font-family:""> </span><span style="font-family:Verdana;">presented and analyzed.</span><span style="font-family:""> </span><span style="font-family:Verdana;">The analysis show</span><span s
文摘Porphyrins occur in a number of important biomolecules and are also synthetically made for use as probe component of chemical and biological sensors. The performance of dye sensitized solar cells with two different porphyrin dyes was investigated in this work. The two porphyrin complexes comprised of a metal-free 5, 10, 15, 20-meso-tetrakis-(9H-2-fluorene-yl) porphyrin (H2TFP) and its Zinc complex (ZnTFP). UV-Vis, Fluorescence, and Fourier transformed infrared measurements of the two dyes were carried out to evaluate their absorption, emission and binding characteristics. Both dyes absorbed light in the UV-visible region all the way to the near-infrared. The surface morphology and elemental analysis of the porphyrin dye sensitized photoanodes were determined using Field Emission Scanning Electron Microscopy Imaging and Transmission Electron Microscopy Imaging. Cyclic voltammetry studies, current-voltage characteristics and the electrochemical impedance spectroscopic studies were also carried out. Solar-to-electric energy efficiency of H2TFP dye sensitized solar cell was higher (0.11%) than that of the zinc complex (0.08%). Thus the metal free porphyrin generated more power than the zinc complex under similar conditions. The impedance measurement also displayed less overall resistance for the free porphyrin (50 Ω) compared with the zinc complex (130 Ω). The LUMO levels of H2TFP and ZnTFP sensitizers were -0.87 eV and -0.77 eV respectively. Both of these LUMO values are higher than the lower bound level of the conduction band of TiO2 (-4.0 eV), ensuring the efficient injection of an electron from the excited porphyrin dye to the conduction band of the titanium dioxide.
文摘A series of barium-tungstate-based phosphors doped with different concentrations of Dy<sup>3+</sup> were synthesized by solid-state reaction method. Photoluminescence properties and decay lifetime of Dy<sup>3+</sup>-doped BaWO<sub>4</sub> samples were studied. The results indicated that luminescent properties of BaWO<sub>4</sub>:Dy<sup>3+</sup> depended on the Dy<sup>3+</sup> concentration, and the inner energy could transfer from to Dy<sup>3+</sup>. The quality of the light was checked by estimating CIE parameters, and the results showed that BaWO<sub>4</sub>:Dy<sup>3+</sup> was a potential candidate as blue-green luminescent materials in white LED because of its excellent emission spectrum excited by UV light.
基金Project supported by the National Natural Science Foundation of China （Nos. 50221201, 90301010, 50502033, 20302088）, the Chinese Academy of Sciences and the National Research Fund for Fundamental Key Projects No. 973 （No. 2006CB806200）.
文摘The nanoparticles of a spirooxazine （SPO） and its photomerocyanine （PMC） were prepared through the reprecipitation method. Two distinct features were observed. One is that the decaying lifetime for PMC nanoparticles was 600 times of that for the dispersed molecules, and the other is that the fluorescence intensity of SPO nanoparticles was enhanced by 240 times of that of the dispersed monomer.
