A tunable white light emitting Na2Ca3Si2O8:Ce3+,Tb3+,Mn2+ phosphor with a high color rendering index (CRI) has been prepared. Under UV excitation, Na2Ca3Si2O8:Ce3+ phosphors present blue luminescence and exhibit a broad excitation ranging from 250 to 400 nm. When codoping Tb3+/Mn2+ ions into Na2Ca3Si2O8, energy transfer from Ce3+ to Tb3+ and Ce3+ to Mn2+ ions is observed from the spectral overlap between Ce3+ emission and Tb3+/Mn2+ excitation spectra. The energy-transfer efficiencies and corresponding mechanisms are discussed in detail. The mechanism of energy transfer from Ce3+ to Tb3+ is demonstrated to be a dipole–quadrupole mechanism by the Inokuti–Hirayama model. The wavelength-tunable white light can be realized by coupling the emission bands centered at 440, 550 and 590 nm ascribed to the contribution from Ce3+, Tb3+ and Mn2+, respectively. The commission on illumination value of color tunable emission can be tuned by controlling the content of Ce3+, Tb3+ and Mn2+. Temperature-dependent luminescence spectra proved the good thermal stability of the as-prepared phosphor. White LEDs with CRI = 93.5 are finally fabricated using a 365 nm UV chip and the as-prepared Na2Ca3Si2O8:Ce3+,Tb3+,Mn2+ phosphor. All the results suggest that Na2Ca3Si2O8:Ce3+,Tb3+,Mn2+ can act as potential color-tunable and single-phase white emission phosphors for possible applications in UV based white LEDs.

A series of Ba4Gd3Na3(PO4)6F2:Eu2+ phosphors with a broad emitting band have been synthesized by a traditional solid state reaction. The crystal structural and photoluminescence properties of Ba4Gd3Na3(PO4)6F2:Eu2+ are investigated. The different crystallographic sites of Eu2+ in Ba4Gd3Na3(PO4)6F2:Eu2+ phosphors have been verified by means of their photoluminescence (PL) properties and decay times. Energy transfer between Eu2+ ions, analyzed by excitation, emission, and PL decay behavior, has been indicated to be a dipole–dipole mechanism. Moreover, the luminescence quantum yield as well as the thermal stability of the Ba4Gd3Na3(PO4)6F2:Eu2+ phosphor have been investigated systematically. The as-prepared Ba4Gd3Na3(PO4)6F2:Eu2+ phosphor can act as a promising candidate for n-UV convertible white LEDs.

New tuneable light-emitting Ca3Al8Si4O17N4:Ce3+/Tb3+/Eu2+ oxynitride phosphors with high brightness have been prepared. When doped with trivalent cerium or divalent europium they present blue luminescence under UV excitation. The energy transfer from Ce3+ to Tb3+ and Ce3+ to Eu2+ ions is deduced from the spectral overlap between Ce3+ emission and Tb3+/Eu2+ excitation spectra. The energy-transfer efficiencies and corresponding mechanisms are discussed in detail, and the mechanisms of energy transfer from the Ce3+ to Tb3+ and Ce3+ to Eu2+ ions are demonstrated to be a dipole–quadrupole and dipole–dipole mechanism, respectively, by the Inokuti–Hirayama model. The International Commission on Illumination value of color tuneable emission as well as luminescence quantum yield (23.8–80.6%) can be tuned by controlling the content of Ce3+, Tb3+ and Eu2+. All results suggest that they are suitable for UV light-emitting diode excitation.

To date, most current reports on the development and optimization of solar spectral converters have described the utilization of energy transfer among rare-earth ions. Here, we introduce non-rare-earth ion Mn4+ to transfer energy to Yb3+, which can exhibit strong near-infrared luminescence. It can harvest UV-blue photons and exhibits intense NIR emission of Yb3+ around 1000 nm, perfectly matching the maximum spectral response of Si solar cells. It demonstrates for the first time that efficient energy transfer occurs with a decrease in the excited state lifetime and red photoluminescence (PL) from Mn4+ with increasing Yb3+ concentration. These results demonstrate that the Mn4+ ions can be an efficient and direct sensitizer harvesting UV-blue photons. It could provide new avenues for developing harvesting Si-based solar cells.

We have synthesized a series of Eu2+ and Eu2+/Tb3+ activated novel GdAl12O18N oxynitride phosphors by a traditional solid state reaction. The structural and photoluminescence properties related to the crystal of GdAl12O18N:Eu2+/Tb3+ phosphor are investigated. Rietveld structure refinement and photoluminescence properties of the obtained phosphor indicate that the GdAl12O18N host has only one type of Gd site. GdAl12O18N:Eu2+,Tb3+ samples exhibit a blue emission band that peaks at 460 nm and a green line that peaks at 550 nm, originating from the Eu2+ and Tb3+ ions, respectively. This energy transfer from Eu2+ to Tb3+ was confirmed by the decay times of energy donor Eu2+. In addition, the mechanism of energy transfer from Eu2+ to Tb3+ ions is demonstrated to be a dipole–quadrupole mechanism by the Inokuti–Hirayama (I–H) model. All the results indicate that the Eu2+ and Tb3+ activated phosphor may be a good candidate for blue-green components in UV white LEDs.

Utilizing Mn2+ and Tb3+ ions as energy-transfer acceptors, we report a series of emission color-tunable Ca2GdZr2(AlO4)3:Ce3+, Mn2+, Tb3+ aluminate garnets. Incorporating Mn2+ and Tb3+ into Ca2GdZr2(AlO4)3:Ce3+ phosphor generates an orange emission band peaking at 572 nm and a green line peaking at 550 nm. The energy transfers from Ce3+ to Mn2+ and Ce3+ to Tb3+ ions are deduced from the spectral overlap between the Ce3+ emission and Mn2+/Tb3+ excitation spectra. Fluorescence decay patterns are studied as a function of Mn2+ and Tb3+ concentration. The calculated values based on the luminescence dynamical process indicate that the intensity ratios of the orange to green bands as a function of Mn2+ concentration are in good agreement with those obtained directly from the emission spectra. We have demonstrated that the color emission as well as the luminescence external quantum yield (20.4–48.9%) can be tuned by precisely controlling the content of Ce3+, Mn2+, and Tb3+. The energy transfer significantly enables the achievement of a broad emission spectrum covering an orange spectral region. It is suitable for near-UV light-emitting diode (LED) excitation.

Eu2+-doped SrSi2O2N2 has recently been identified as a viable green phosphor that in conjunction with a blue-emitting diode can be used in solid-state white-lighting sources. In this study, we attempt to improve the photoluminescence and thermal quenching behavior by codoping Re3+ (Re = La, Gd, Y, Dy, Lu, Sc) and Li+ instead of Sr2+. Trivalent cation substitution at the Sr2+ site enhances the photoluminescence intensities and also achieves better thermal stability at high temperature. The lifetime decay properties in the related substituted phosphors are investigated. Furthermore, under the 460 nm blue light irradiation, this green phosphor exhibits excellent luminescence properties with absorption and internal/external efficiencies. High-color-rendition warm-white LEDs using the phosphor have the color temperature and color rendition of 4732 K and 91.2, respectively, validating its suitability for use in solid-state white lighting.

A new, highly efficient deep red-emitting phosphor Ca14Al10Zn6O35:Mn4+ was developed as a component of solid-state white light-emitting diodes (LEDs). The structural and optical characterization of the phosphor is described. The phosphor exhibits strong emission in the range of 650–700 nm when excited by 460 nm excitation, with a quantum efficiency approaching 50%. Concentration dependence of Mn4+ luminescence in Ca14Al10Zn6O35:Mn4+ is investigated. Attempts to understand the thermal stability on the basis of the thermal quenching characteristics of Ca14Al10Zn6O35:Mn4+ is presented. The results suggest that phosphors deriving from Ca14Al10Zn6O35:Mn4+ have potential application for white LEDs. In addition, influence of cation substitution on the luminescence intensity of these phosphors is elucidated.

•A novel full-color emitting phosphor CaScAlSiO6:Ce3+, Tb3+, Eu3+ are synthesized and investigated.•The obtained phosphor exhibits three emission bands.•The CIE chromaticity coordinates (0.30, 0.30) and high color rendering index CRI=88 can be achieved.•These results indicated that CSAS:Ce3+, Tb3+, Eu3+ is a promising single-composition full-color emitting phosphor.We reported a single-phased CaScAlSiO6:Ce3+, Tb3+, Eu3+ as a potential full-color emitting phosphor for the application in fluorescent lamps. The CaScAlSiO6:Ce3+, Tb3+, Eu3+ phosphor exhibits three bands under 254 nm excitation: one band situated at 380 nm is attributed to the 5d→4f transitions of Ce3+ ions, the second band with sharp lines peaked at 542 nm is assigned to the 5D4→7FJ transitions of Tb3+ ions, the third band in the orange–red region (580–700 nm) is originated from 5D0→7FJ transitions of Eu3+ ions. The Commission Internationale de I’Eclairage (CIE) chromaticity coordinates (0.30, 0.30) and high color rendering index (CRI=88) can be achieved upon excitation of 254 nm light. It is suggested that CaScAlSiO6:Ce3+, Tb3+, Eu3+ can serve as a potential single-phased full-color emitting phosphor for phosphor-converted fluorescent lamps.

Emission-tunable Mg2Al4Si5O18:Eu2+, Mn2+ and Mg2Al4Si5O18:Eu2+, Tb3+ cordierite phosphors have been synthesized by a high-temperature solid-state reaction technique. Photoluminescence and energy transfer in Mg2Al4Si5O18:Eu2+, Mn2+ occur via a resonance-type dipole–quadrupole interaction mechanism, and the critical distance of the energy transfer is calculated to be 11.1 A. We found that the emission colors could be tuned from blue (0.19, 0.26) to white (0.41, 0.37) via the energy transfer of Eu2+ → Mn2+ and from blue to green (0.28, 0.45) via the energy transfer of Eu2+ → Tb3+. The green emission is realized in the Mg2Al4Si5O18:Eu2+, Tb3+ phosphors on the basis of the highly efficient energy transfer from the Eu2+ to Tb3+ ions. Finally, the color tunable emission with varied hues has been obtained in Eu2+, Tb3+, or Mn2+ activated Mg2Al4Si5O18 phosphors, making them potential emission-tunable phosphors for near-UV LEDs.

An orange-emitting phosphor was obtained via efficient Ce3+–Mn2+ and Eu2+–Mn2+ energy transfers in La9.33(SiO4)6O2, and has been developed for solid state UV/near-UV white lighting applications. The luminescence properties and energy transfer from Ce3+ to Mn2+ and Eu2+ to Mn2+ are investigated. The La9.33(SiO4)6O2:Ce3+, Mn2+ phosphor shows a blue emission centered at 380 and an orange emission peaking at 590 nm, which could be ascribed to the allowed 5d → 4f transition of the Ce3+ ion and the 4T1g(4G) → 6A1g(6S) transition of the Mn2+ ion, respectively. Upon excitation at 365 nm, the Eu2+, Mn2+ co-doped La9.33(SiO4)6O2 phosphor exhibits the Eu2+ green emission band and the Mn2+ orange emission band. Non-radiative transitions between the Ce3+/Eu2+ and Mn2+ ions in the La9.33(SiO4)6O2 host are both demonstrated to be attributable to dipole–quadrupole interactions. The intensity ratio of the Mn2+ emission bands can be enhanced through the increase of the Mn2+ content, which is attributed to the efficient energy transfer from Ce3+/Eu2+ to Mn2+, and the corresponding chromaticity coordinates (0.50, 0.38), (0.51, 0.46) were obtained with the La9.33(SiO4)6O2:Ce3+, Mn2+ and La9.33(SiO4)6O2:Eu2+, Mn2+ samples. Results indicated that the as-prepared phosphors might have promising applications in white-light LEDs as an orange-emitting phosphor.

A tunable white light emitting Na2Ca3Si2O8:Ce3+,Tb3+,Mn2+ phosphor with a high color rendering index (CRI) has been prepared. Under UV excitation, Na2Ca3Si2O8:Ce3+ phosphors present blue luminescence and exhibit a broad excitation ranging from 250 to 400 nm. When codoping Tb3+/Mn2+ ions into Na2Ca3Si2O8, energy transfer from Ce3+ to Tb3+ and Ce3+ to Mn2+ ions is observed from the spectral overlap between Ce3+ emission and Tb3+/Mn2+ excitation spectra. The energy-transfer efficiencies and corresponding mechanisms are discussed in detail. The mechanism of energy transfer from Ce3+ to Tb3+ is demonstrated to be a dipole–quadrupole mechanism by the Inokuti–Hirayama model. The wavelength-tunable white light can be realized by coupling the emission bands centered at 440, 550 and 590 nm ascribed to the contribution from Ce3+, Tb3+ and Mn2+, respectively. The commission on illumination value of color tunable emission can be tuned by controlling the content of Ce3+, Tb3+ and Mn2+. Temperature-dependent luminescence spectra proved the good thermal stability of the as-prepared phosphor. White LEDs with CRI = 93.5 are finally fabricated using a 365 nm UV chip and the as-prepared Na2Ca3Si2O8:Ce3+,Tb3+,Mn2+ phosphor. All the results suggest that Na2Ca3Si2O8:Ce3+,Tb3+,Mn2+ can act as potential color-tunable and single-phase white emission phosphors for possible applications in UV based white LEDs.

To date, most current reports on the development and optimization of solar spectral converters have described the utilization of energy transfer among rare-earth ions. Here, we introduce non-rare-earth ion Mn4+ to transfer energy to Yb3+, which can exhibit strong near-infrared luminescence. It can harvest UV-blue photons and exhibits intense NIR emission of Yb3+ around 1000 nm, perfectly matching the maximum spectral response of Si solar cells. It demonstrates for the first time that efficient energy transfer occurs with a decrease in the excited state lifetime and red photoluminescence (PL) from Mn4+ with increasing Yb3+ concentration. These results demonstrate that the Mn4+ ions can be an efficient and direct sensitizer harvesting UV-blue photons. It could provide new avenues for developing harvesting Si-based solar cells.

Utilizing Mn2+ and Tb3+ ions as energy-transfer acceptors, we report a series of emission color-tunable Ca2GdZr2(AlO4)3:Ce3+, Mn2+, Tb3+ aluminate garnets. Incorporating Mn2+ and Tb3+ into Ca2GdZr2(AlO4)3:Ce3+ phosphor generates an orange emission band peaking at 572 nm and a green line peaking at 550 nm. The energy transfers from Ce3+ to Mn2+ and Ce3+ to Tb3+ ions are deduced from the spectral overlap between the Ce3+ emission and Mn2+/Tb3+ excitation spectra. Fluorescence decay patterns are studied as a function of Mn2+ and Tb3+ concentration. The calculated values based on the luminescence dynamical process indicate that the intensity ratios of the orange to green bands as a function of Mn2+ concentration are in good agreement with those obtained directly from the emission spectra. We have demonstrated that the color emission as well as the luminescence external quantum yield (20.4–48.9%) can be tuned by precisely controlling the content of Ce3+, Mn2+, and Tb3+. The energy transfer significantly enables the achievement of a broad emission spectrum covering an orange spectral region. It is suitable for near-UV light-emitting diode (LED) excitation.

New tuneable light-emitting Ca3Al8Si4O17N4:Ce3+/Tb3+/Eu2+ oxynitride phosphors with high brightness have been prepared. When doped with trivalent cerium or divalent europium they present blue luminescence under UV excitation. The energy transfer from Ce3+ to Tb3+ and Ce3+ to Eu2+ ions is deduced from the spectral overlap between Ce3+ emission and Tb3+/Eu2+ excitation spectra. The energy-transfer efficiencies and corresponding mechanisms are discussed in detail, and the mechanisms of energy transfer from the Ce3+ to Tb3+ and Ce3+ to Eu2+ ions are demonstrated to be a dipole–quadrupole and dipole–dipole mechanism, respectively, by the Inokuti–Hirayama model. The International Commission on Illumination value of color tuneable emission as well as luminescence quantum yield (23.8–80.6%) can be tuned by controlling the content of Ce3+, Tb3+ and Eu2+. All results suggest that they are suitable for UV light-emitting diode excitation.