Highly Efficient Cyan-Green Emission in Self-Activated Rb₃RV₂O₈ (R = Y, Lu) Vanadate Phosphors for Full-Spectrum White Light-Emitting Diodes (LEDs)

Abstract

Phosphor-converted white-light-emitting diodes (pc-WLEDs) rely on combining a near-ultraviolet (n-UV) or blue chip with trichromatic and yellow-emitting phosphors. It is challenging to discover cyan-green-emitting (480–520 nm) phosphors for compensating the spectral gap and producing full-spectrum white light. In this work, we successfully discovered two unprecedented bright cyan-green emitting Rb3RV2O8 (R = Y, Lu) phosphors that gives emission bands centered at 500 nm upon 362 nm n-UV light excitation. Interestingly, the both self-activated compounds exhibit high internal quantum efficiencies (IQEs) of 71% for Rb3YV2O8 and 85% for Rb3LuV2O8, respectively. Moreover, controllable emission color can be successfully tuned from cyan-green to orange-red across the warm white light region by design strategy of VO4 3– → Eu3+ energy transfer. The thermal quenching of as-prepared phosphors could be effectively mitigated by this design strategy. Finally, the as-fabricated n-UV (λex = 370 nm) pumped phosphor-converted (pc) W-LED devices utilizing Rb3RV2O8 (R = Y, Lu) along with commercial phosphors demonstrate well-distributed warm white light with high color-rendering index (CRI) of 91.9 and 93.5, and a low correlated color temperature (CCT) of 5095 and 4946 K. It suggests that the both vanadate phosphors have potential applications in full-spectrum pc-WLEDs.

High‐temperature persistent luminescence and visual dual‐emitting optical temperature sensing in self‐activated CaNb2O6: Tb3+ phosphor

“…The values of lifetime of Tb 3+ ion emission are determined to be 492.12, 574.16, 577.43, 589.79, and 619.06 μs as shown in Figure 4C, which gradually increase with the increasing of Tb 3+ concentration. This is because, the excited electrons in the host are gradually transferred to the 5 d excited state of Tb 3+ , extending the emission lifetime of Tb 3+ 20 . Figures 4B and C further illustrates the energy transfer between the host and Tb 3+ in the CNO: Tb 3+ phosphors.…”

“…This is because, the excited electrons in the host are gradually transferred to the 5d excited state of Tb 3+ , extending the emission lifetime of Tb 3+ . 20 Figures 4B and C further illustrates the energy transfer between the host and Tb 3+ in the CNO: Tb 3+ phosphors. For the purpose of explaining the energy transfer between the host and the Tb 3+ ion in CNO: Tb 3+ more intuitively, we calculated the energy transfer efficiency (ETE) by formula (2):…”

Luminescence in external dopant-free scandium-phosphorus vanadate solid solution: a spectroscopic and theoretical investigation

“…81 However, this situation is reasonable and can be understandable because the Sc(P x ,V 1Àx )O 4 solid solutions belong to the family of selfactivated phosphors whose luminescence is mainly due to the existence of complex groups and/or defects. 82 As a result, in most cases, the self-activated phosphors usually can only show QE values less than 50%, such as those summarized by Dang et al, 83 Huang et al, 84 and Zhou et al, 85 83 and those summarized by Huang et al, 84 and Zhou et al 85 Looking into the IQE and/or EQE values we obtained, it is obvious that some of them, typically for the Sc(P 0.3 ,V 0.7 )O 4 sample, are comparable to and can even be higher than those of many reported self-activated phosphors and some other RE/non-RE doped crystals, such as ScVO 4 :0.02Bi 3+ (l ex = 330 nm xenon lamp, EQE = 35%), 25 CsPbCl 3 (l ex = 360 nm xenon lamp, QY = 26.0 AE 0.3%), 90 Cs x K 1Àx PbCl 3 :Eu 3+ (l ex = 365 nm xenon lamp, EQE = 31.2%), 91 and CsPbCl 3 :Mn 2+ (l ex = 360 nm xenon lamp, QY = 27%). 92 Moreover, the improved thermal stability (T 50% ) of 480.15 K and/ or activation energies (DE a ) of 0.51 eV for the Sc(P 0.4 ,V 0.6 )O 4 solutions are also higher than or comparable to those of some RE/non-RE doped phosphors, for example, La 2 MgTiO 6 :0.005Bi 3+ (l ex = 350 nm xenon lamp, T 50% = B175 1C, DE a = 0.27 eV), 4 La 2 MgTiO 6 :0.005Bi 3+ (l ex = 410 nm xenon lamp, T 50% = B250 1C, DE a = 0.252 eV), 6 CaSc 2 O 4 :Ce 3+ (l ex = 437 nm, T 50% = B225 1C, DE a = 0.195 eV), 60 (DE a = 0.469 eV, T 50% = B60 1C), 94 CsVO 3 (DE a = 0.31 eV).…”

Near‐Unity Cyan‐Green Emitting Lead‐Free All‐Inorganic Cesium Copper Chloride Phosphors for Full‐Spectrum White Light‐Emitting Diodes

“…At present, only a few kinds of cyan‐green‐emitting phosphors have been investigated, such as BaSi 2 O 2 N 2 :Eu 2+ , Ba 0.75 Sr 0.25 Si 2 O 2 N 2 :Eu 2+ , Ca 2 LaZr 2 Ga 3 O 12 :Ce 3+ , (Sr,Ba) 5 (PO 4 ) 3 Cl:Eu 2+ , and (Lu 2 Mg) (Al 4 Si)O 12 :Ce 3+ . [ 11–14 ] However, these rare earth doped phosphors suffer from 1) low photoluminescence quantum yield (PLQY < 80%), and 2) high cost due to the use of rare earth ions and high synthesis temperature (>900 ºC). Furthermore, the full width at half maximum (FWHM) of these phosphors is relatively narrow (20–60 nm), making it difficult to perfectly make up for the “cyan cavity”.…”