Oxy-fluoride glasses with composition of 25SiO2-65PbF2-9.4AlF3-0.1HoF3-0.5YbF3 were prepared. Their up-conversion fluorescence characteristics were investigated by 980 nm laser. Two emission peaks were observed at 540...Oxy-fluoride glasses with composition of 25SiO2-65PbF2-9.4AlF3-0.1HoF3-0.5YbF3 were prepared. Their up-conversion fluorescence characteristics were investigated by 980 nm laser. Two emission peaks were observed at 540 and 650 nm. The up-conversion mechanism and processes were analyzed. The relationship between pumping power and relative intensity of emissions was discussed. From the dependence, it is known that the emissions centered at 540 and 650 nm are both attributed to two-photon process.展开更多
Ho3＋/yb3＋ co-doped LiYF4 single crystals with various Yb3＋ concentrations and ,-~ 0.98 mol% Ho3＋ concentration are grown by the Bridgman method under the conditions of taking LiF and YF3 as raw materials and a tem...Ho3＋/yb3＋ co-doped LiYF4 single crystals with various Yb3＋ concentrations and ,-~ 0.98 mol% Ho3＋ concentration are grown by the Bridgman method under the conditions of taking LiF and YF3 as raw materials and a temperature gradient （40 ~C/cm-50 ~C/cm） for the solid-liquid interface. The luminescent performances of the crystals are investigated through emission spectra, infrared transmittance spectrum, emission cross section, and decay curves under excitation by 980 nm. Compared with the Ho3＋ single-doped LiYF4 crystal, the Ho3＋/yb3＋ co-doped tiYf4 single crystal has an obviously enhanced emission band from 1850 nm to 2150 nm observed when excited by a 980-nm diode laser. The energy transfer from Yb3＋ to Ho3＋ and the optimum fluorescence emission around 2.0 p-m of Ho3＋ ions are investigated. The maximum emission cross section of the above sample at 2.0 p.m is calculated to be 1.08 × 10-20 cm2 for the LiYF4 single crystal of 1-mol% Ho3＋ and 6-mo1% Yb3＋ according to the measured absorption spectrum. The high energy transfer efficiency of 88.9% from Yb3＋ to Ho3＋ ion in the sample co-doped by Ho3＋ （1 mol%） and Yb3＋ （8 tool%） demonstrates that the Yb3＋ ions can efficiently sensitize the Ho3＋ ions.展开更多
The Ho3＋/yb3＋ co-doped a-NaYF4 single crystal was grown successfully for the first time by a modified Bridgman method in which KF was used as assisting flux and a large temperature gradient （70-90℃ /cm） of solid-...The Ho3＋/yb3＋ co-doped a-NaYF4 single crystal was grown successfully for the first time by a modified Bridgman method in which KF was used as assisting flux and a large temperature gradient （70-90℃ /cm） of solid-liquid interface was adopted. Upconversion emissions at green -544 nm, red -657 and -751 nm were obtained under 980 nm laser diode excitation. The intensity at -544 nm was much stronger than those of -657 and -751 nm. The mechanisms of the upconversion emissions were investigated by studying the relationship between the upconversion intensity and pump power. The optimized Yb3＋ concentration was about 8.08moi% when Ho3＋ concentration was hold at about 1.0mol%. The results showed that Ho3＋/yb3＋ doped α-NaYF4 single crystal was a possible candidate upconversion material for the green solid-state laser.展开更多
The goal of this work was aimed to improve the power conversion efficiency of single crystalline silicon-based photovoltaic cells by using the solar spectral conversion principle, which employs an up-conversion phosph...The goal of this work was aimed to improve the power conversion efficiency of single crystalline silicon-based photovoltaic cells by using the solar spectral conversion principle, which employs an up-conversion phosphor to convert a low energy infrared photon to the more energetic visible photons to improve the spectral response. In this study, the surface of multicrystalline silicon solar cells was coated with an up-conversion molybdate phosphor to improve the spectral response of the solar cell in the near-infrared spectral range. The short circuit current （Isc）, open circuit voltage （Voc）, and conversion efficiency （η） of spectral conversion cells were measured. Preliminary experimental results revealed that the light conversion efficiency of a 1.5%–2.7% increase in Si-based cell was achieved.展开更多
文摘Oxy-fluoride glasses with composition of 25SiO2-65PbF2-9.4AlF3-0.1HoF3-0.5YbF3 were prepared. Their up-conversion fluorescence characteristics were investigated by 980 nm laser. Two emission peaks were observed at 540 and 650 nm. The up-conversion mechanism and processes were analyzed. The relationship between pumping power and relative intensity of emissions was discussed. From the dependence, it is known that the emissions centered at 540 and 650 nm are both attributed to two-photon process.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51472125 and 51272109)the K.C.Wong Magna Fund in Ningbo University,China(Grant No.NBUWC001)
文摘Ho3＋/yb3＋ co-doped LiYF4 single crystals with various Yb3＋ concentrations and ,-~ 0.98 mol% Ho3＋ concentration are grown by the Bridgman method under the conditions of taking LiF and YF3 as raw materials and a temperature gradient （40 ~C/cm-50 ~C/cm） for the solid-liquid interface. The luminescent performances of the crystals are investigated through emission spectra, infrared transmittance spectrum, emission cross section, and decay curves under excitation by 980 nm. Compared with the Ho3＋ single-doped LiYF4 crystal, the Ho3＋/yb3＋ co-doped tiYf4 single crystal has an obviously enhanced emission band from 1850 nm to 2150 nm observed when excited by a 980-nm diode laser. The energy transfer from Yb3＋ to Ho3＋ and the optimum fluorescence emission around 2.0 p-m of Ho3＋ ions are investigated. The maximum emission cross section of the above sample at 2.0 p.m is calculated to be 1.08 × 10-20 cm2 for the LiYF4 single crystal of 1-mol% Ho3＋ and 6-mo1% Yb3＋ according to the measured absorption spectrum. The high energy transfer efficiency of 88.9% from Yb3＋ to Ho3＋ ion in the sample co-doped by Ho3＋ （1 mol%） and Yb3＋ （8 tool%） demonstrates that the Yb3＋ ions can efficiently sensitize the Ho3＋ ions.
基金This work was supported by the National Natural Science Foundation of China （No.51472125, No.51272109） and K. C. Wong Magna Fund in Ningbo University.
文摘The Ho3＋/yb3＋ co-doped a-NaYF4 single crystal was grown successfully for the first time by a modified Bridgman method in which KF was used as assisting flux and a large temperature gradient （70-90℃ /cm） of solid-liquid interface was adopted. Upconversion emissions at green -544 nm, red -657 and -751 nm were obtained under 980 nm laser diode excitation. The intensity at -544 nm was much stronger than those of -657 and -751 nm. The mechanisms of the upconversion emissions were investigated by studying the relationship between the upconversion intensity and pump power. The optimized Yb3＋ concentration was about 8.08moi% when Ho3＋ concentration was hold at about 1.0mol%. The results showed that Ho3＋/yb3＋ doped α-NaYF4 single crystal was a possible candidate upconversion material for the green solid-state laser.
基金Project supported by National Science Council of Taiwan (NSC98-2113-M-009-005-MY3)
文摘The goal of this work was aimed to improve the power conversion efficiency of single crystalline silicon-based photovoltaic cells by using the solar spectral conversion principle, which employs an up-conversion phosphor to convert a low energy infrared photon to the more energetic visible photons to improve the spectral response. In this study, the surface of multicrystalline silicon solar cells was coated with an up-conversion molybdate phosphor to improve the spectral response of the solar cell in the near-infrared spectral range. The short circuit current （Isc）, open circuit voltage （Voc）, and conversion efficiency （η） of spectral conversion cells were measured. Preliminary experimental results revealed that the light conversion efficiency of a 1.5%–2.7% increase in Si-based cell was achieved.
