Ag-SiO2-Er2O3 Nanocomposites: Highly Effective Upconversion Luminescence at High Power Excitation and High Temperature

Abstract

Rare Earth (RE) activated upconversion phosphors (UCPs), have demonstrated significant application potentials in some front fields, including solar energy conversion and bio-application. However, some bottleneck problems should be overcame, such as the lower upconversion efficiency, narrower excitation band, concentration-quenching and temperature-quenching. To solve these problems, the Ag-SiO2-Er2O3 nanocomposites were fabricated, in which the upconversion luminescence (UCL) of Er2O3 was white broadband. Through the interaction of Er2O3 with surface plasmon (SP) of silver nanoparticles (SNPs), the threshold power for generating broadbands was suppressed largely in contrast to the Er2O3 nanoparticles (NPs), while the UCL brightness was enhanced remarkably, ranging from several to 104 times, which strongly depended on the power density of excitation light. At excitation power density of 1.50 W/mm2 of 980 nm light, the UCL intensity of Ag-SiO2-Er2O3 is 40-folds than the well-known NaYF4:Yb3+,Er3+ commercial powders. And more, it is also interesting to observe that the composites demonstrate two excitation bands extending of 780–980 nm, highly improved UCL with elevated temperature and excitation power density. The UCL mechanism related to UCL enhancement was carefully studied.

Near-Infrared Emission and Photon Energy Upconversion of Two-Dimensional Copper Silicates

“…This trend is also observed in other literatures [22][23] , which is probably caused by photon avalanche or thermal avalanche 24 . Fig.…”

“…On the other hand, at high pumping densities, the 3d levels of Cu 2+ would become saturated, therefore enabling the promotion of electrons further to the conduction band. This multiphoton process associate with a photon avalanche mechanism was supported by the photocurrent measurement for several RE 3+ doped compounds and the white emission has been ascribed to a charge transfer process 22,[33][34][35] . Indeed, laser damage occurs for the copper silicate pigments, despite that thermal analysis indicate the stability of these compounds under 1273 K (Fig.…”

Improved fluorescence properties of core–sheath electrospun nanofibers sensitized by silver nanoparticles

“…Previous studies showed that most core-sheath fluorescent materials were designed with Ag as the core and a luminescent substrate as the sheath [16,28,29,31]. In the present study, coresheath nanofibers with Ag-NPs/PVP as the core and Tb(acac) 3 phen/PLLA as the sheath were also prepared to further verify the effect of the location of Ag layer in the core-sheath structure on the fluorescence intensity of the fibers.…”

“…In previous research, the methods adopted to control the distance between the metal nanoparticles and the RE complexes include (1) the import of long-chain macromolecules, biomacromolecules, or multilayer Langmuir-Blodgett (LB) films to metal nanoparticles [24][25][26][27], a relatively complex and difficult process because of the complicated physical and chemical reactions involved; (2) the introduction of an inorganic silica (SiO 2 ) transition layer, the thickness of which can be controlled by reaction time and temperature [28][29][30][31]. However, in most previous studies, a precious metal was used as the inner layer and a fluorophore was used as the outer layer.…”

Broadband, White Light Emission from Doped and Undoped Insulators

“…Over the last several years, numerous works have reported a broadband, white-light emission from insulating powders under intense, near infrared (IR) excitation. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] The materials investigated are usually nano-powders of insulators, such as yttrium oxide, yttrium silicate, Al 2 O 3 , GGG, and others, either pure or doped with rare earth ions (e.g. Er, Nd, Yb, Tm) or transition metal ions (e.g.…”