Blue to green emission and energy transfer between Ce³⁺ ions in Ca₁₅Si₂₀O₁₀N₃₀

Abstract

A near-ultraviolet (near-UV) excited phosphor, Ca 15 Si 20 O 10 N 30 :Ce 3+ , was synthesized by a solid state reaction, and the crystal structure and luminescence properties were investigated in detail. Ca 15 Si 20 O 10 N 30 crystallizes in a cubic unit cell with space group Pa3 _ and the lattice parameters were determined to be a = b = c = 15.4195 (3) Å. The maximum emission wavelength can be tuned from about 470 nm to 520 nm as the content of Ce 3+ increases due to the energy transfer between various Ce 3+ activators located at 10 different coordination environments, which was verified by the time-resolved emission spectra (TRES) and the variation in decay rate with respect to the detection wavelength. Upon excitation at 365 nm, Ca 15 Si 20 O 10 N 30 :Ce 3+ exhibited a relatively low thermal quenching, and the T 50 is measured to be 233 °C. The above results indicate that Ca 15 Si 20 O 10 N 30 :Ce 3+ is a promising candidate for application in white light emitting diodes (white LEDs).

Full-Spectrum White Light-Emitting Diodes Enabled by an Efficient Broadband Green-Emitting CaY2ZrScAl3O12:Ce3+ Garnet Phosphor

“…Since D q is proportional to 1/ R 5 , the introduction of a Ce 3+ luminescence center into the CaY 2 ZrScAl 3 O 12 lattice to replace Y 3+ ions will enhance the crystal field strength as the Ce 3+ ionic radius ( r = 1.143 Å, CN = 8) to be larger than that of Y 3+ ( r = 1.019 Å, CN = 8), and hence, the average M 3+ -O (M = Y 3+ or Ce 3+ ) lattice distance shortens. Ce 3+ substitution in CaY 2 ZrScAl 3 O 12 : x Ce 3+ phosphors thus weakens high-energy emission and strengthens low-energy emission, which is observable as a redshift in PL spectra. , The possibility that energy transfer between Ce 3+ activators may also contribute to the emission redshift cannot be discounted . High Ce 3+ concentrations will strengthen their interactions with the host lattice, accounting for the expanded FWHM …”

“…46,47 The possibility that energy transfer between Ce 3+ activators may also contribute to the emission redshift cannot be discounted. 48 High Ce 3+ concentrations will strengthen their interactions with the host lattice, accounting for the expanded FWHM. 35 Figure 4d shows the dependence of PL intensity of CaY 2 ZrScAl 3 O 12 :xCe 3+ on Ce 3+ doping concentration.…”

Preparation, crystal structure and photoluminescence properties of Ce3+ activated Ba3Y1−yLuyAl2O7.5 phosphors for near-UV LEDs

“…Firstly, using the energy transfer principle, the multicolor phosphors can be realized by co-doping sensitizers and activators into the same matrix, 12,13 such as Sr 7.3 Ca 2.7 (PO 4 ) 6 F 2 :Eu 2+ , Mn 2+ , 14 La 5 Si 2 BO 13 :Ce 3+ , Mn 2+ , 15 MgGd 4 Si 3 O 13 :Ce 3+ ,Tb 3+ , 16 it always have a larger adjustable for the emission color, but the regulation and control are complicated and the energy efficiency is always low. Secondly, by doping the same rare earth ions in a multi-sites matrix, the different emission color from different luminescence centers are mixed up to form multicolor emission, such as 19 This is a relatively simple way due to the stable structure and the invariant ratio for the different sites. Meanwhile, the color of emission spectrum will be relatively complete, because the comprehensive manifestation of color comes from the superposition of the emission spectrum of different sites.…”