YunLe Wei

Tunable white luminescence and energy transfer in novel Cu + , Sm 3+ co-doped borosilicate glasses for W-LEDs

The luminescent properties of novel Cu⁺, Sm³⁺ single- and co-doped borosilicate glasses were systematically investigated by absorption, excitation, emission spectra and decay curves. Cu⁺ single-doped glasses emit broad luminescence band covering all the visible range. And their peaks shift to blue with decreasing excitation wavelength from 330 to 280 nm. Cu⁺, Sm³⁺ co-doped samples generate the varied hues from blue white to pure white and eventually to yellow white due to an efficient energy transfer from Cu⁺ to Sm³⁺. Our research indicates the potential application of Cu⁺, Sm³⁺ co-doped borosilicate glasses as converting phosphors for white LEDs pumped by UV LED chips.

Sb3+/Mn2+ co-doped tunable white emitting borosilicate glasses for LEDs.

Luminescent properties of Sb(3+)/Mn(2+) co-doped borosilicate glasses containing no rare earth ions were systematically investigated through absorption, excitation, emission spectra, and decay curves. Upon 250-340 nm light excitation, the glasses exhibit broad blue emission at 400 nm (Sb(3+)) and red emission at 615 nm (Mn(2+)). The varied emitted color from blue through white and eventually to red can be obtained by properly tuning the content of Mn(2+) ions due to energy transfer from Sb(3+) to Mn(2+). Our investigation shows that Sb(3+)/Mn(2+) co-doped glasses may provide a new platform to design and fabricate luminescent materials for UV LED chips in the future.

Enhanced upconversion in novel KLu 2 F 7 :Er 3+ transparent oxyfluoride glass-ceramics

Novel Er3+ doped highly transparent glass-ceramics containing orthorhombic KLu2F7 nanocrystals (24 nm in diameter) have been successfully fabricated for the first time. Their structural, optical and upconversion properties are systematically investigated by XRD, TEM, absorption spectra, upconversion spectra and lifetime measurements. Excited by 980 nm laser, characteristic emissions of Er3+ are detected in all samples. Impressively, the upconversion luminescence of Er3+ is drastically enhanced (1340 and 680 times for green and red emissions, respectively) after crystallization. Laser power dependence of the upconverted emissions and upconversion decay curves were explored to understand the different upconversion mechanisms in precursor glasses and glass-ceramics. Results show that the enrichment of Er3+ into KLu2F7 lattice after crystallization is responsible for the enhanced upconversion.

Enhanced emissions in Tb3+-doped oxyfluoride scintillating glass ceramics containing KLu2F7 nano-crystals

Abstract KLu 2 F 7 : Tb 3+ oxyfluoride glass ceramics (GC) were successfully manufactured via traditional melt-quenching route with further heat-treatment. Their micro-structural and optical properties were systemically investigated by XRD, TEM, HRTEM techniques, transmittance spectra, excitation spectra, emission spectra, luminescence lifetime measurements and X-ray excited luminescence (XEL). Both photoluminescence and XEL of KLu 2 F 7 GC doped with Tb 3+ are highly enhanced after further heat-treatment resulting from the partition of Tb 3+ ions into the KLu 2 F 7 crystalline lattice with low phonon energy. Our investigation suggests that such Tb 3+ -doped transparent KLu 2 F 7 glass ceramics may present potential application in X-ray scintillator for slow event detection.

Luminescence and energy transfer process in Cu + ,Sm 3+ co-doped sodium silicate glasses

Highly transparent Cu+, Sm3+ co-doped sodium silicate glasses were prepared by melt-quenching technique. The optical and luminescent properties of Cu+, Sm3+ single-doped and co-doped glasses, and energy transfer process from Cu+ to Sm3+ were systemically investigated through absorption, excitation, emission spectra and lifetime measurement. Tuning the concentration of Sm3+ can generate the varied hues from yellowish green to orange. Our results suggest that Cu+, Sm3+ co-doped glasses may be used as converting phosphors for UV-excitation white LEDs.