During the past few decades, the research on persistent luminescent materials has focused mainly on Eu2+-doped compounds. However, the yearly number of publications on non-Eu2+-based materials has also increased steadily. By now, the number of known persistent phosphors has increased to over 200, of which over 80% are not based on Eu2+, but rather, on intrinsic host defects, transition metals (manganese, chromium, copper, etc.) or trivalent rare earths (cerium, terbium, dysprosium, etc.). In this review, we present an overview of these non-Eu2+-based persistent luminescent materials and their afterglow properties. We also take a closer look at some remaining challenges, such as the excitability with visible light and the possibility of energy transfer between multiple luminescent centers. Finally, we summarize the necessary elements for a complete description of a persistent luminescent material, in order to allow a more objective comparison of these phosphors.

/pdf/persistent-luminescence-in-non-eu2-doped-compounds-a-review-54ofy0pdn0.pdf

Persistent Luminescence in Non-Eu2+-Doped Compounds: A Review.

By doping an organic compound functioning as an electron donor (hereinafter referred to as donor molecules) into an organic compound layer contacting a cathode, donor levels can be formed between respective LUMO (lowest unoccupied molecular orbital) levels between the cathode and the organic compound layer, and therefore electrons can be injected from the cathode, and transmission of the injected electrons can be performed with good efficiency. Further, there are no problems such as excessive energy loss, deterioration of the organic compound layer itself, and the like accompanying electron movement, and therefore an increase in the electron injecting characteristics and a decrease in the driver voltage can both be achieved without depending on the work function of the cathode material.

Light Emitting Device

Sulfide-based luminescent materials have attracted a lot of attention for a wide range of photo-, cathodo- and electroluminescent applications. Upon doping with Ce3+ and Eu2+, the luminescence can be varied over the entire visible region by appropriately choosing the composition of the sulfide host. Main application areas are flat panel displays based on thin film electroluminescence, field emission displays and ZnS-based powder electroluminescence for backlights. For these applications, special attention is given to BaAl2S4:Eu, ZnS:Mn and ZnS:Cu. Recently, sulfide materials have regained interest due to their ability (in contrast to oxide materials) to provide a broad band, Eu2+-based red emission for use as a color conversion material in white-light emitting diodes (LEDs). The potential application of rare-earth doped binary alkaline-earth sulfides, like CaS and SrS, thiogallates, thioaluminates and thiosilicates as conversion phosphors is discussed. Finally, this review concludes with the size-dependent luminescence in intrinsic colloidal quantum dots like PbS and CdS, and with the luminescence in doped nanoparticles.

https://biblio.ugent.be/publication/1243707/file/1243737.pdf

Luminescence in Sulfides: A Rich History and a Bright Future.

A novel blue-emitting long-lasting proyphosphate phosphor Sr2P2O7:Eu2+.Y3+

Disclosed herein is a light emitting device including one or more light emitting diodes to primarily emit light having different wavelengths in the wavelength range of ultraviolet rays and/or blue light, and a wavelength-conversion means to convert the primary light into secondary light in the visible light wavelength range. The light emitting device of the current invention has a high color temperature of 2000 to 8000 K or 10000 K and a high color rendering index of 90 or more, thus easily realizing desired emission on the color coordinate system. Therefore, the lighting emitting device is applicable to mobile phones, notebook computers, and keypads or backlight units for various electronic products, and, in particular, automobiles and exterior and interior lighting fixtures.

White light emitting device comprising a plurality of light emitting diodes with different peak emission wavelengths and a wavelength converter

Thermally stimulated luminescence studies for dysprosium doped strontium tetraborate

Thermoluminescence studies of rare earth doped Sr2Mg(BO3)2 phosphor

Thermoluminescence (TL) characteristics and dosimetric properties of Ba 2 Ca(BO 3 ) 2 phosphor doped with Tb 3+ exposed to gamma-ray irradiation are reported for the first time. Firstly, the influence of different rare earth dopants, i.e. Dy 3+ , Tb 3+ and Tm 3+ , on TL of Ba 2 Ca(BO 3 ) 2 phosphor is discussed. All glow curves consist of two TL peaks located at 109-120 °C and 199-220 °C and Tb 3+ -doped Ba 2 Ca(BO 3 ) 2 phosphor exhibits the highest TL sensitivity. Secondly, the effects of concentration of Tb 3+ and gamma-ray irradiation dose on TL are investigated. The optimum Tb 3+ concentration is 2 mol% and the TL kinetic parameters of Ba 2 Ca(BO 3 ) 2 : 0.02Tb are calculated by the peak shape method. The high-temperature peak for this sample shifts to higher temperature with increasing irradiation dose. Furthermore, the dosimetric properties of Ba 2 Ca(BO 3 ) 2 :0.02Tb phosphor, i.e. the pre-irradiation annealing treatment, reproducibility and linearity, are studied, the results of which indicate that Tb 3+ -doped Ba 2 Ca(BO 3 ) 2 phosphor has a potential application in the personal protection dosimetry field. TL emission of the phosphor is observed to peak at about 485, 542, 580 and 625 nm originating from the characteristic transitions of Tb 3+ .

Thermoluminescence characteristics of terbium‐doped Ba2Ca(BO3)2 phosphor

Influence of co-doping different rare earth ions on CaGa2S4: Eu2+, RE3+(RE=Ln) phosphors

We observed that the SrMg2(PO4)2:Eu phosphor could emit long life phosphorescence with the excitation light whose wavelength was shorter than 420nm, however, when La, Ce, or Gd was codoped, the wavelength of the excitation light to cause the phosphorescence had a redshift of 40nm. A possible mechanism and related discussion for this redshift phenomenon of the excitation light was given. It was suggested that the threshold between the trap and valence band was decreased with the addition of the codopants.

Qiang Su

Papers

Thermally stimulated luminescence studies for dysprosium doped strontium tetraborate

Thermoluminescence studies of rare earth doped Sr2Mg(BO3)2 phosphor

Thermoluminescence characteristics of terbium‐doped Ba2Ca(BO3)2 phosphor

Influence of co-doping different rare earth ions on CaGa2S4: Eu2+, RE3+(RE=Ln) phosphors

Redshift phenomenon of the excitation light of long life emission phosphor