Jiayan Liao

Enhancement of the up-conversion luminescence of Yb3+/Er3+ or Yb3+/Tm3+ co-doped NaYF4 nanoparticles by photonic crystals

A new method for enhancing the upconversion (UC) emission of rare-earth doped nanoparticles is reported, in which Yb3+/Er3+ or Yb3+/Tm3+ co-doped NaYF4 nanoparticles are deposited on to the surface of photonic crystal (PC) films. The UC emission of the Yb3+/Er3+ or Yb3+/Tm3+ co-doped NaYF4 nanoparticles on the PC surface was notably enhanced when the UC emission bands of the Yb3+/Er3+ or Yb3+/Tm3+ co-doped NaYF4 nanoparticles were within the range of the photonic band gap of the PCs, indicating that the PCs were efficient and selective reflection mirrors. The results show that PCs may have potential applications in UC optoelectronics and lighting devices.

Preparation and upconversion emission modification of crystalline colloidal arrays and rare earth fluoride microcrystal composites.

In this paper, highly ordered crystalline colloidal arrays containing rare earth fluoride microcrystals were fabricated. The upconversion emission property of rare earth fluoride microcrystals in crystalline colloidal arrays was studied and modified. A significant suppression and enhancement of the upconversion emission from the rare earth fluorides can be observed in the regions of the photonic band gap and its band edge, respectively. The suppression or enhancement factor was shown to be related to the ordered degree of the crystalline colloidal arrays and is critical in the preparation of upconversion displays and low-threshold lasers.

Color tunable upconversion emission in CeO2:Yb,Er three-dimensional ordered macroporous materials

Abstract The three-dimensional ordered macroporous CeO 2 :Yb,Er materials were prepared, and the influence of doping concentration of Yb 3+ or Er 3+ ions on upconversion property was investigated. Green and red upconversion emissions were observed under the excitation of 980 nm at room temperature. It was found that the ratio of red to green upconversion emission intensity increased with increasing of concentration of the Yb 3+ or Er 3+ ions in the three-dimensional ordered macroporous CeO 2 :Yb,Er materials. When the concentration of Yb 3+ was 10 mol.%, pure red upconversion emission was obtained. The varied mechanism of ratio of red to green upconversion emission intensity was discussed with the concentration of Yb 3+ or Er 3+ ions.

Investigation on existing states and photoluminescence property of silver in the SiO2 three-dimensionally ordered macroporous materials

The photoluminescence properties of silver species, including Ag+, Ag+–Ag+, Ag0, and Ag nanoparticles in various matrices, such as gel and glass have been extensively reported. In the present study, we present the preparation of silver including SiO2 three-dimensionally ordered macroporous (3DOM) materials and investigate the existing states and photoluminescence property of silver in the SiO2 3DOM materials. The results show that only Ag+ ions exist in the SiO2 3DOM materials sintered at temperature below 400 °C. With the increasing sintering temperature, the Ag+ ions gradually transform into Ag+–Ag+, where simultaneously, a part of Ag+–Ag+ transform into Ag nanoparticles. The Ag+–Ag+ and Ag nanoparticles are formed in the SiO2 3DOM materials sintered at temperature from 450 to 650 °C. Finally, only Ag nanoparticles occur in the SiO2 3DOM materials prepared at 750 °C. The formation mechanisms of Ag species were discussed in the SiO2 3DOM materials.

Enhancement of near-infrared to near-infrared upconversion emission in the CeO₂: Er³⁺, Tm³⁺, Yb³⁺ inverse opals.

In this Letter, CeO₂: Er³⁺, Tm³⁺, Yb³⁺ inverse opal with near-infrared to near-infrared upconversion emission was prepared by polystyrene colloidal crystal templates, and the influence of photonic bandgap on the upconversion emission was investigated. Comparing with the reference sample, suppression of the blue or red upconversion luminescence was observed in the inverse opals. It is interesting that the near-infrared upconversion emission located at about 803 nm was enhanced due to the inhibition of visible upconversion emission in the inverse opals. Additionally, the variety of upconversion emission mechanisms was observed and discussed in the CeO₂: Er³⁺, Tm³⁺, Yb³⁺ inverse opals.

UPCONVERSION LUMINESCENCE ENHANCEMENT OF NaYF4:Yb3+, Er3+ NANOPARTICLES ON INVERSE OPAL SURFACE

LaPO4 inverse opal photonic crystals with different photonic band gaps were fabricated by template-assisted method. The Yb3+/Er3+ co-doped NaYF4 nanoparticles were deposited on the surfaces of the inverse opals, and their up-conversion emission properties were investigated. The upconversion emissions of Yb3+/Er3+ co-doped NaYF4 nanoparticles on the inverse opal surfaces have been enhanced when the upconversion emission bands of the nanoparticles are in the range of photonic band gaps of the inverse opals, which is attributed to an efficient and selective reflection of photonic band gaps.

Investigation of upconversion and near infrared emission properties in CeO 2 : Er 3+ , Yb 3+ inverse opals

The upconversion emission of rare earth ions can be modified in photonic crystals, however, the influence of upconversion emission modification of rare earths on near infrared emission has not been investigated yet in the photonic crystals. In the paper, CeO₂: Er³⁺, Yb³⁺ inverse opals with the photonic band gaps at 545, 680 and 450 nm were prepared by polystyrene colloidal crystal templates. The upconversion and the near infrared emission properties of Er³⁺ ions were systematically investigated in the CeO₂: Er³⁺, Yb³⁺ inverse opals. Comparing with the reference sample, significant suppression of both the green and red upconversion luminescence of Er³⁺ ions were observed in the inverse opals. It is interesting that the infrared emission located at 1,560 nm was enhanced due to inhibition of upconversion emission in the inverse opals. Additionally, mechanism of upconversion emission of the inverse opal was discussed. The photon avalanche upconversion process is observed.

Upconversion luminescence and color tunable properties in Yb-Tb codoped Ca0.15Zr0.85O1.85 inverse opal

The upconversion (UC) luminescence and color tunable properties of Tb3+ ions were investigated by steady spectral under 980 LD excitation in the Ca0.15Zr0.85O1.85:Yb,Tb inverse opals fabricated by the self-assembly technique in combination with a sol-gel method. The inhibition of UC emission was inspected if the Tb3+ UC emission band was in the regions of the photonic bandgap, while enhancement of the UC emission occurred if the UC emission band located at the edge of the bandgap. Color modification of the UC emission was successfully obtained by the suppression or enhancement effect of the photonic band gap on the UC emission.

Upconversion Emission Modification and White Light Generation in NaYF 4 :Yb 3+ , Er 3+ , Tm 3+ Nanocrystals/Opal Photonic Crystal Composites

In this paper, we fabricated NaYF 4:Yb³⁺, Er³⁺, Tm³⁺ nanocrystal/opal photonic crystal composites by depositing NaYF 4:Yb³⁺, Er³⁺, Tm³⁺ nanocrystals on the surface of opal photonic crystals, and we investigated the influence of photonic bandgaps on upconversion (UC) emission properties of NaYF 4:Yb³⁺, Er³⁺, Tm ³⁺ nanocrystals. When the photonic bandgaps overlapped with the UC emission bands of NaYF 4:Yb³⁺, Er³⁺, Tm³⁺ nanocrystals on the opal photonic crystal surfaces, the suppression or enhancement of UC emissions was observed due to the Bragg reflection effect of photonic crystal, resulting in the modification of red, green, and blue UC emissions. Thus, white UC emission was realized.

PHOTONIC CRYSTAL SURFACE ENHANCED UPCONVERSION EMISSION OF YF3:Yb3+, Er3+ NANOPARTICLES

The opal photonic crystals made of polystyrene microspheres with 155, 230, 270 or 410 nm in diameter were used to enhance upconversion (UC) emission of YF3:Yb3+, Er3+ nanoparticles, respectively. The red or green UC emission of YF3:Yb3+, Er3+ nanoparticles can be selectively enhanced when the red or green UC emission wavelength overlapped with the photonic bandgaps of opals, which is attributed to Bragg reflection of photonic bandgap. In addition, when the 980 nm excitation light wavelength was in the region of the photonic bandgap, red and green UC emissions of YF3:Yb3+, Er3+ nanoparticles were enhanced due to the enhancement of excitation field.