Upconversion Nanoparticles: Synthesis, Photoluminescence Properties, and Applications

Synthesis of SrF2:Yb:Er ceramic precursor powder by co-precipitation from aqueous solution with different fluorinating media: NaF, KF and NH4F

“…50 The synthesis methods developed are scalable 51 and can be used to obtain nanoparticles in industrial volumes. The nanoparticles obtained can be used to increase the efficiency of solar panels, 35,[52][53][54][55][56] in anticounterfeiting, 57 in the production of thin optical films for anti-reflective protective coatings on glass, 58 in 2D/3D monitors, 59 in bioimaging, 33 pressure and temperature sensors, 60 and in plastic sorting. 61 The physicochemical regularities revealed confirmed the possibility of synthesising precursor powders for laser ceramics using the method of precipitation from aqueous solutions.…”

Effect of the fluorinating agent type (NH4F, NaF, KF) on the particle size and emission properties of SrF2:Yb:Er luminophores

“…1 The maximum theoretical quantum yields for upconversion luminescence are 50%, 33.33% and 25% for two-, three-and four-photon processes, respectively. [2][3][4] In order to be used in nanothermometry, 5,6 up-conversion lasers, 7 dosimeters, 8 bioimaging, [9][10][11][12][13] solar panel efficiency enhancement, [14][15][16][17][18][19][20] anticounterfeiting, [21][22][23] vacuum measurement, 24 and laser cooling, 25 powders with particle sizes in the range of tens of nanometres to tens of microns are required, including those with a core-shell structure. The powders generally have a lower up-conversion PLQY due to the increase in surface area, which is the source of luminescence quenching.…”

Preparation of rare-earth doped NaYF4 luminescent nanoparticles by a high-energy ball milling process

“…The interest in these materials is explained by their ability to luminesce in a wide spectral range under low-energy infrared excitation, which opens significant prospects for application in various areas: nanophotonics, medical therapy and bioimaging, photocatalytic processes, solar energy, anti-counterfeit fluorescent labels, etc. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Among various oxides and other halide-based photoluminescent (PL) NPs, fluoride compounds with high chemical stability possess remarkable properties such as wide spectral range transparency and low phonon energies of the lattice, [17][18][19] which determine their unique PL properties. Currently, NaYF 4 -based NPs co-doped with 20 mol% Yb 3+ /2 mol% Er 3+ and 20 mol% Yb 3+ /0.6 mol% Tm 3+ ions are well-explored and popular PL materials for various applications in photonics, both in up-and down-conversion excitation mechanisms.…”

“…21,[26][27][28][29] The structural peculiarities, such as the local symmetry of the active centers and atomic arrangement in the lattice, substantially affect the PL efficiency of these crystals. The reduction of REE local symmetry in the hexagonal β-NaYF 4 phase (C 3h ) compared with the cubic α-NaYF 4 (D 4v ) leads to a significant increase of PL intensity, 18,19,28 facilitating β-NaYF 4 -based NPs, one of the best up-conversion phosphors for practical applications until now.…”