Yb^(3+)-doped phosphors have characteristic near-infrared(NIR)emissions,but their applications in phosphor-converted light-emitting-diodes(pc-LEDs)and Si solar cells are limited due to their mismatching excitation spe...Yb^(3+)-doped phosphors have characteristic near-infrared(NIR)emissions,but their applications in phosphor-converted light-emitting-diodes(pc-LEDs)and Si solar cells are limited due to their mismatching excitation spectra.Here,we selected nitride La3 Si6 N11(LSN)as host material to achieve Yb^(3+)NIR emission upon low-energy charge transfer(CT)excitation.The obtained phosphor LSN:Yb^(3+)has a broad CT excitation band ranging from 250 to 500 nm and narrowband NIR emissions ranging from 950 to 1100 nm centered at 983 nm.On the basis of spectral data,the vacuum referred binding energies(VRBE)schemes are constructed to locate energy levels of all lanthanide ions in LSN.We also fabricated NIR pc-LED device using 395 nm LED chip to demonstrate the potential applications of LSN:Yb^(3+)phosphors.展开更多
Increases of emission intensities for Eu 3+ at the S 6 site relative to that at the C 2 site were observed as UV excitation wavelength decreases from 300 nm to 200 nm in both bulk and nanocrystalline cubic Y 2O 3...Increases of emission intensities for Eu 3+ at the S 6 site relative to that at the C 2 site were observed as UV excitation wavelength decreases from 300 nm to 200 nm in both bulk and nanocrystalline cubic Y 2O 3:Eu 3+. Decomposition of excitation spectra shows that the charge transfer band of Eu 3+ at the S 6 site lies in the high-energy side of that at the C 2 site, resulting in that the energy transfer from the host prefers to the S 6 site. Detailed emission and excitation spectral characteristics were analyzed and discussed. In addition, spectral red-shift were found in both charge transfer bands in nanocrystalline Y 2O 3:Eu 3+ compared to the bulk material. The number ratio of S 6 sites to C 2 sites is also smaller in nanocrystalline Y 2O 3:Eu 3+ than that in the bulk one.展开更多
Nanocrystalline Y_2O_3∶Eu powders doped with different metal ions M (M: Li +,Na +,K +,Mg (2+),Sr (2+),Ba (2+),B (3+) and Al (3+)) were synthesized by glycine combustion. Their structure and luminescent properties wer...Nanocrystalline Y_2O_3∶Eu powders doped with different metal ions M (M: Li +,Na +,K +,Mg (2+),Sr (2+),Ba (2+),B (3+) and Al (3+)) were synthesized by glycine combustion. Their structure and luminescent properties were studied and compared with each other. The nanocrystalline Y_2O_3 were cubic in symmetry by XRD pattern. It can be concluded that co-doping can modify the size and crystallinity of nanoparticles. As a consequence,the luminescent properties such as the fluorescent intensity,lifetime of (() 5D_0)-(() 7F_2) and the location of charge transfer band (CT band) vary with co-dopants. The variation depends more strongly on the crystallinity of nanoparticles than the size. Especially,in Li +-doped Y_2O_3∶Eu nanoparticles,the emission intensity improves as large as three times than that of undoped ones.展开更多
基金Project supported by National Natural Science Foundation of China(51832005,51972020)。
文摘Yb^(3+)-doped phosphors have characteristic near-infrared(NIR)emissions,but their applications in phosphor-converted light-emitting-diodes(pc-LEDs)and Si solar cells are limited due to their mismatching excitation spectra.Here,we selected nitride La3 Si6 N11(LSN)as host material to achieve Yb^(3+)NIR emission upon low-energy charge transfer(CT)excitation.The obtained phosphor LSN:Yb^(3+)has a broad CT excitation band ranging from 250 to 500 nm and narrowband NIR emissions ranging from 950 to 1100 nm centered at 983 nm.On the basis of spectral data,the vacuum referred binding energies(VRBE)schemes are constructed to locate energy levels of all lanthanide ions in LSN.We also fabricated NIR pc-LED device using 395 nm LED chip to demonstrate the potential applications of LSN:Yb^(3+)phosphors.
文摘Increases of emission intensities for Eu 3+ at the S 6 site relative to that at the C 2 site were observed as UV excitation wavelength decreases from 300 nm to 200 nm in both bulk and nanocrystalline cubic Y 2O 3:Eu 3+. Decomposition of excitation spectra shows that the charge transfer band of Eu 3+ at the S 6 site lies in the high-energy side of that at the C 2 site, resulting in that the energy transfer from the host prefers to the S 6 site. Detailed emission and excitation spectral characteristics were analyzed and discussed. In addition, spectral red-shift were found in both charge transfer bands in nanocrystalline Y 2O 3:Eu 3+ compared to the bulk material. The number ratio of S 6 sites to C 2 sites is also smaller in nanocrystalline Y 2O 3:Eu 3+ than that in the bulk one.
文摘Nanocrystalline Y_2O_3∶Eu powders doped with different metal ions M (M: Li +,Na +,K +,Mg (2+),Sr (2+),Ba (2+),B (3+) and Al (3+)) were synthesized by glycine combustion. Their structure and luminescent properties were studied and compared with each other. The nanocrystalline Y_2O_3 were cubic in symmetry by XRD pattern. It can be concluded that co-doping can modify the size and crystallinity of nanoparticles. As a consequence,the luminescent properties such as the fluorescent intensity,lifetime of (() 5D_0)-(() 7F_2) and the location of charge transfer band (CT band) vary with co-dopants. The variation depends more strongly on the crystallinity of nanoparticles than the size. Especially,in Li +-doped Y_2O_3∶Eu nanoparticles,the emission intensity improves as large as three times than that of undoped ones.
