Preparation And Up-conversion Luminescence Characteristics Of Fluoride Tellurite Glass

Tow low energy photons can be transformed into a higher frequency photon byupconversion fluorescence materials, therefor, they have been applicated widely inthe upconversion laser field, infrared indicator cards, bio-lables andthree-dimensional displays technology, and so on．In recent years, upconversionmaterials for application in solar cells gradually rise. However, most of them are stillat the experimental stage. Main reason has two aspects: on the one hand, theupconversion efficiency of material is lower, on the other hand, the lack ofcombination technology between upconversion materials and solar cells.On the premise of material with high efficiency and easy to combine with solarcells, fluoride upconversion material Er3+, Yb3+doped tellurite glasses and PbF2:Yb3+,Er3+nanoparticals were synthesized. Concrete research contents are in the following:1. Luminescence properties of Er3+doped TeO2–PbF2glasses were investigated.The most intense green emission peak is at around544nm, corresponding to the4S43/2â†'I15/2transition of Er3+. Two weaker emissions bands around524nm and657nmcan be observed corresponding to the2H11/2â†'4I15/2and4F9/2â†'4I15/2transitions of Er3+,respectively.2. We successfully prepared Er3+-Yb3+co-doped TeO2-PbF2oxyfluoride telluriteglasses with different Yb3+concentrations and characterized their upconversionproperties. Intense emission bands at527,544, and657nm corresponded to the Er3+transitions, and the maximum was obtained at an Yb3+-to-Er3+molar ratio of3. Whenthis glass was applied at the back of amorphous silicon solar cells in combinationwith a rear reflector, a0.45%improvement in efficiency was obtained underco-excitation of AM1.5and400mW980nm laser radiation. Maximum externalquantum efficiency and luminescence quantum efficiency of0.27%and1.35%,respectively, were achieved at300mW excitation.3. A series of Er3+-doped TeO2-PbF2glasses with and without Ag nanoparticleswas prepared by the conventional melt-quenching method, and structural and optical characterizations were performed. The influence of Ag nanoparticles on the structural,absorption and upconversion properties was determined by comparing Er3+single-doped samples under different annealing durations. Upconversionluminescence spectra were found to be generally controlled by the structuralproperties of the host matrix. Green emission was quenched after annealing becauseof Ag nanoparticle absorption. However, green and red emissions were enhancedwhen annealing time was extended to24h as a result of local field effect caused byAg nanoparticles.4. PbF2:Yb3+,Er3+nanoparticles were synthesized using the hydrothermalmethod．The upconversion (UC) luminescence properties of products obtained underdifferent Yb3+doping concentrations and annealing temperatures were theninvestigated. As the Yb3+concentration increased, the product structures transformedfrom a mixed phase to a cubic phase. Their total emission, however, were remarkablylow. After annealing, the UC emission of the products was enhanced because of theirincreased grain size. The maximum emission was obtained with7%Yb3+. Theproducts were applied in a hydrogenated amorphous silicon solar cell, and an externalquantum efficiency of0.04%was measured under the illumination of a980nm laserat4.8W/cm2.