ABSTRACT
Tm3+, Ho3+, Yb3+ co-doped YPO4 micro-nano tubes were synthesized by hydrothermal method. Under the 980 nm near infrared (NI) excitation, the micro-nano tubes emitted red, green, blue visible light and a near infrared emission centered at 795 nm. The optical properties and structure of the synthesized Tm3+, Ho3+, Yb3+ co-doped YPO4 micro-nano tubes were characterized by testing the TEM, XRD and fluorescence spectra. The results showed that the micro-nano tubes are pure hexagonal phase. The hydrothermal temperature had obvious effect on fluorescence spectra but little effect on phase. The intensity of the emission peaks didn't increase with the concentration of doping ions monotonously under the same reaction temperature, but changed non-monotonously due to the concentration quenching and cross relation. The possible upconversion (UC) mechanism was discussed in this paper. This UC emission intensity controllable fluorescent material has potential application in three dimension solid display, UC illumination, fluorescence detection and some other fields.
ABSTRACT
A numerical investigation of the effect of grating antireflective layer structure on the photoelectric conversion efficiency of solar cells was carried out by the finite-difference time-domain method. The influence of grating shape, height and the metal film thickness coated on grating surface on energy storage was analyzed in detail. It was found that the comparison between unoptimized and optimized surface grating structure on solar cells shows that the optimization of surface by grating significantly increases the energy storage capability and greatly improves the efficiency, especially of the photoelectric conversion efficiency and energy storage of the triangle grating. As the film thickness increases, energy storage effect increases, while as the film thickness is too thick, energy storage effect becomes lower and lower.
