Structure and photoluminescence properties of novel Ca₂NaSiO₄F:Re (Re = Eu²⁺, Ce³⁺, Tb³⁺) phosphors with energy transfer for white emitting LEDs

Abstract

A series of Eu 2+ and Ce 3+ /Tb 3+ doped Ca 2 NaSiO 4 F (CNSOF) phosphors have been synthesized and their structure and photoluminescence properties have been investigated in detail. Rietveld structure refinement indicates that the phosphors crystalized in an orthorhombic system with a space group of Pnma (no. 62) and there are two kinds of cation sites for the doped ions to occupy in forming emission centers. The CNSOF:Eu 2+ and CNSOF:Ce 3+ phosphors both have broad excitation bands, which match well with the commercial UV LED chips. The CNSOF:Eu 2+ phosphor can have intense green emission with a maximum at 530 nm under irradiation at 380 nm, while the CNSOF:Ce 3+ sample can emit intense blue light, peaking at 470 nm with excitation at 365 nm. By codoping the Tb 3+ and Ce 3+ ions into an CNSOF host and varying their relative ratio, tunable blue-green colors are obtained due to efficient energy transfer from the Ce 3+ to Tb 3+ ions. Moreover, energy transfer mechanisms for the Eu 2+ ions in CNSOF:Eu 2+ and Ce 3+ / Tb 3+ in CNSOF:Ce 3+ ,Tb 3+ have been studied systematically. Our investigation indicates that CNSOF:Eu 2+ and CNSOF:Ce 3+ ,Tb 3+ may be potential green and blue-green phosphors for UV WLEDs, respectively.

Luminescence properties and its red shift of blue-emitting phosphor Na3YSi3O9:Ce3+for UV LED

“…The nonradiative thermal relaxation process results in decreased luminescence intensity. 38 The full width at the half maximum (FWHM) of PL spectrum increases with the temperature, which can be described by using the Boltzmann distribution: where W 0 is the FWHM at 0 K, hv represents the vibrational phonon energy which interacts with the electronic transitions, S means the Huang-Rhys parameter, and k is the Boltzmann constant. It is assumed that hv is the same for both 4f ground state and 5d excited state of Ce 3+ ions.…”

Chromaticity-Tunable and Thermal Stable Phosphor-in-Glass Inorganic Color Converter for High Power Warm w-LEDs

“…The starting model was built with crystallographic data known for the YAG structure (ICSD-20090). The refinement pattern of MYASG:0.05Ce 3+ is displayed in Figure 1b, and the reliability refinement factors of R wp and R p were determined to be 10.03% and 7.62%, respectively, suggesting that the atom positions, fraction factors, and temperature factors of YMASG:0.05Ce 3+ all well satisfy the reflection conditions [15]. The final refined crystallographic data and reliability factors for the sample are listed in Table 1.…”

Luminescence properties of novel yellowish-green-emitting phosphor KBaBP2O8:Tb3+

“…As is well known, Tb 3+ ‐doped phosphors often have narrow line‐shaped excitation peaks in the NUV region, and are normally not efficient enough due to the parity‐forbidden 4f–4f transitions of Tb 3+ . To improve the excitation efficiency of Tb 3+ ‐doped phosphors in the NUV region, Tb 3+ co‐doped with Ce 3+ /Eu 2+ is one efficient way to improve the luminous efficiency under NUV excitation through the energy transfer from Ce 3+ /Eu 2+ to Tb 3+ . So, the above method should be performed in the subsequent work in order to improve the excitation efficiency of our Tb 3+ ‐doped KBaBP 2 O 8 :Tb 3+ phosphor upon NUV excitation.…”