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Upconversion Luminescence Of Er3+/Yb3+ Codoped KLaF4 Nanorods Prepared By Hydrothermal Method

Posted on:2015-12-20Degree:MasterType:Thesis
Country:ChinaCandidate:W B LaiFull Text:PDF
GTID:2271330461474669Subject:Microelectronics and Solid State Electronics
Abstract/Summary:PDF Full Text Request
Rear earth upconverting luminescent phosphors have many advantages, such as high chemical stability and optical stability, sharp emission lines, low toxicity, long emission lifetimes and low excitation energy. Therefore they can be widely applied in laser medium, display and lighting, anti-counterfeiting technology, medical treatment, optical communication, and so on. KLaF4 nanorods, which often has much lower phonon energy compared to other fluoride, can be used as matrix phosphors materials. In this thesis, Er3+/Yb3+ codoped KLaF4 nanorods were prepared by hydrothermal method, and the influence of Yb3+ doping concentration and preparation techniques on the properties (crystalline phase, morphology and upconversion performance) of Er3+/Yb3+ codoped KLaF4 nanorods have been characterized by XRD, TEM, FT-IR, UV-Vis-NIR and PL. The main results were obtained as follows:1、We studied the influence of preparation techniques, such as annealing temperature, reaction time, reaction temperature and the value of pH, on the crystalline phase, morphology and upconversion performance of the samples. With the increasing of the annealing temperature, reaction time and reaction temperature, it was found that the crystalline quality of KLaF4 nanorods became better, the size of particle was increased, the intensities of red and green upconversion fluorescence were also increased under the excitation at 980 nm. Compared with NH4F used as the source of F element, KF·2H2O could contribute to obtain hexagonal KLaF4 nanorods with better crystalline quality and stronger PL intensity. With the increasing of the pH value of the precursor, the crystalline quality of KLaF4 nanorods became better, the size of particle increased, the upconversion intensities were strengthened too. Therefore, the pH value of the precursor was suitable to be 13-14.2、We studied the influence of Yb3+ doping concentration on the upconversion performance in Er3+/Yb3+ codoped KLaF4 nanorods. With the increasing of Yb3+ doping concentration, the absorption of the light near 973 nm became stronger, however, the intensity of upconversion fluorescence decreased. Besides, the fluorescence decay curve of 2H11/2 level was fitted to the double exponential curve, but its average fluorescence lifetime decreased with the increasing of Yb3+ doping concentration. The sample with 2at%Er/10at.%Yb:KLaF4 has the-strongest upconversion fluorescence and the highest average fluorescence lifetime is about 80 us.Besides, the downconversion performance of Pr3+ codoped KLaF4 nanorods, prepared by hydrothermal method, has been discussed. The good red downconversion fluorescence for Pr:KLaF4 nanorods were obtained under the excitation at 480 nm.In a word, Er3+/Yb3+ or Pr3+ doped KLaF4 nanorods have been synthetised by hydrothermal method. In addition, the optimum process parameters and the doping ions concentration rate have been obtained, which may be helpful for preparing thin film solar cells with much higher conversion efficiency.
Keywords/Search Tags:hydrothermal method, upconversion fluorescence, Er3+/Yb3+:KLaF4 nanorods
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