A down-converted light emitting combination that generates a visible light when an ultraviolet light is incident is provided. The down-converted light emitting combination includes a first structure made of a first material that generates a visible light of a first color when an ultraviolet light of a first wavelength range is incident and a second structure made of a second material that generates a visible light of a second color different from the first color when the ultraviolet light of a second wavelength range different from the first wavelength range is incident, and the first material and the second material have different emission colors and distributions of intensities of the visible lights generated depending on a wavelength of the incident ultraviolet light.

A new concept of bi-luminescent security pigments includes lanthanide doped rare-earth compound with rare-earth free compound and its ink formulation. The unique features of this bi-luminescent security ink is that it emits two different colors when it is illuminated by using two different excitation wavelengths. This important feature makes it most suitable for printing of security codes or QR codes/security images on currency, important official documents, food and medicinal packaging etc. The prospective use of this bi-luminescent security ink provides a ground-breaking opening for easily printable, highly stable and unclonable bi-luminescent security codes for anti-counterfeiting applications.

A high-energy LED is provided, in particular based on the n-polar technique, comprising a Eu.sup.3+ activated converter material based on tungsten/molybdenum oxide. Surprisingly, these materials do not show any saturation.

The present invention relates to a light emitting device comprising a red-emitting Eu.sup.3+ material and green emitting Ce.sup.3+ material which are matched so that the resulting white light has an increased lumen equivalent of radiation for a given color rendering index than with the prior art.

The present invention concerns a luminescent particle comprising a nanoparticle of formula
A.sub.1-xLn.sub.xVO.sub.4(1-y)(PO.sub.4).sub.y  (I)
in which A is selected from yttrium (Y), gadolinium (Gd), lanthanum (La), and mixtures thereof; Ln is selected from europium (Eu), dysprosium (Dy), samarium (Sm), neodymium (Nd), erbium (Er), ytterbium (Yb), and mixtures thereof; 0<x<1; and 0≤y<1; characterized in that the nanoparticle on its surface has tetraalkylammonium cations in an amount such that said nanoparticle has a zeta potential, ζ, of less than or equal to −28 mV in an aqueous medium with a pH≥5, more particularly with a pH≥5.5, and with an ionic conductivity >100 μS.Math.cm.sup.−1. It also concerns a method for preparing such luminescent particles, a colloidal suspension of these particles, and the use thereof as a diagnostic agent, and also a diagnostic kit comprising such luminescent particles.

An optical storage phosphor, a method for checking an authenticity feature, and an apparatus for carrying out a method, relate to an authenticity feature and to a value document. An inorganic optical storage phosphor is provided having a garnet structure and predetermined composition.

The present invention relates to a light emitting device comprising a red-emitting Eu.sup.3+ material and green emitting Ce.sup.3+ material which are matched so that the resulting white light has an increased lumen equivalent of radiation for a given color rendering index than with the prior art.

The present invention relates to an in vitro method for detecting and/or quantifying a biological or chemical substance of interest in a liquid sample, by a capillary action test using, as probes, photoluminescent inorganic nanoparticles, of formula A.sub.1-xLn.sub.xVO.sub.4(1-y)(PO.sub.4).sub.y (II), in which Ln is selected from europium (Eu), dysprosium (Dy), samarium (Sm), neodymium (Nd), erbium (Er), ytterbium (Yb), thulium (Tm), praseodymium (Pr), holmium (Ho) and mixtures thereof; A is selected from yttrium (Y), gadolinium (Gd), lanthanum (La), lutetium (Lu), and mixtures thereof; 0<x<1; and 0≤y<1, said method employing detection of the luminescence, with an emission lifetime shorter than 100 ms, of the nanoparticles, after one-photon absorption, by excitation of the matrix at a wavelength less than or equal to 320 nm.

It also relates to a capillary action test device comprising, as probes, the aforementioned nanoparticles, as well as the use of such a method for purposes of in vitro diagnostics.

The present disclosure relates to a phosphor ceramic comprising a plurality of luminescence conversion materials, wherein a luminescence conversion material serves as a matrix material for the others.

A down-converted light emitting combination that generates a visible light when an ultraviolet light is incident is provided. The down-converted light emitting combination includes a first structure made of a first material that generates a visible light of a first color when an ultraviolet light of a first wavelength range is incident and a second structure made of a second material that generates a visible light of a second color different from the first color when the ultraviolet light of a second wavelength range different from the first wavelength range is incident, and the first material and the second material have different emission colors and distributions of intensities of the visible lights generated depending on a wavelength of the incident ultraviolet light.