Preparation And Properties Of Rare Earth Doped Y2O3/ZNO Upconversion Luminescent Films

Solar photovoltaic industry has become one of the new energy industries for its green environmental protection,safety,reliability and renewable that has been researched and developed in recent decades.Solar panels are mainly based on silicon semiconductors,which can only absorb and utilize the energy in the solar visible region not the energy of the infrared light.But the infrared light which takes up more than 50%of total energy.Therefore,the solar energy cannot be fully and reasonably utilized,resulting in the severe loss of energy.In order to solve the problem,the luminescent films maybe placed in the Si solar cells which convert low energy photons(near infrared light,NIR)to higher energy ones(visible light)and enhance photoelectric conversion efficiency.In this paper,Y2O3 and ZnO are used as mixed matrix,rare earth ions as luminescent centers(Er3+,Ho3+)and sensitizer(Yb3+).The Er3+-Yb3+ and Ho3+-Yb3+co-doped Y2O3/ZnO up-conversion luminescence thin films were prepared by inorganic sol-gel method,respectively.The up-conversion films were detected with such as FE-SEM,XRD,fluorescences pectrophotometer and so on.Here,the effects of the activator concentration(Er3+,Ho3+)and the concentration of sensitizer(Yb3+)on the microstructure and properties of the up-conversion luminescence thin films were studied.The main conclusions were as follows:(1)The effect of Er3+concentration on the photoluminescence of Y2O3/ZnO up-conversion films was studied.The results showed that Er3+concentration has no obvious influences on the film’s grain size and its crystallization degree.The emission intensity increased when the concentration of Er3+ ions increased from 2 mol%to 4 mol%.However,when Er3+ concentration exceeded a certain critical value(self-quenching concentration),the fluorescence quenching would occur in the luminescence process.And the optimum Yb3+ concentration was found at 4 mol%.(2)The effect of the Yb3+ concentration on the structure and photoluminescence properties of Y2O3/ZnO films was discussed.By research,with the increase of Yb3+concentration,the up-conversion luminescence intensities of the films increased at first and then declined.When the concentration of Yb3+ ion was 4mol%,the Y2O3/ZnO film had the highest degree of crystallinity,the biggest grain size and the highest red and green fluorescence luminescence intensity.(3)The effect of the Ho3+ concentration on the structure and photoluminescence properties of Y2O3/ZnO films was discussed.The analysis showed that the intensity of the up-conversion film increased first with the increasing of the Ho3+concentration.When the Ho3+ concentration was 7 mol%,the granules of the film was relatively uniform distribution and the particles size were uniform.With the Ho3+ concentration further increasing,the up-conversion luminescence intensities of the films declined and the agglomeration phenomenon appeared.