Research On The Infrared Quantum Cutting Down-conversion And Energy Transfer Mechanism

Solar energy is inexhaustible, unpolluted, safe, healthy energy source. Atpresent, the research and application of solar energy has made great development,but the main problem is to improve the efficiency and control costs. In fact, the solarspectrum utilization rate of solar cells is not high. For this kind of situation, wemake use of solar spectrum infrared quantum cutting to improve the photoelectricconversion efficiency of solar cells in this paper.In chapter one, we discuss the background and introduce main contents. Inchapter two, the basic theory of luminescence of rare earth ions is described. Inchapter three, the preparation methods of nanometer materials and methods forcharacterization of the sample are summarized. In the fourth and fifth chapter, twodifferent materials preparation of three systems of rare earth doped ions andluminescence properties of the sample are studied respectively. Emission intensityof the samples doped with different amount of boric acid and the relationshipbetween the emission intensity of Yb³⁺and its doping amount are analyzed.Specifically, with the increase of doping concentration, concentration quenching ofthe luminescence intensities happens. This study mainly includes the followingcontents and results:1. We prepare GdBO₃:Eu³⁺,Ce³⁺,Yb³⁺nano-powders using combustionsynthesis method. We use XRD, SEM and other means of transient fluorescencespectrometer to characterize structures and morphologies of the samples. Firstly, theabsorption spectroscopy of the samples is tested and a strong absorption peak at973nm is obtained. Then we use the light source of973nm to monitor the excitation ofthe samples and find that there are two excitation peaks at254nm and360nm.Finally, we use these two wavelengths as excitation wavelengths to investigate theemission spectroscopy of the samples, and the results show the following twoenergy transitions: Eu³⁺�'Yb³⁺and Ce³⁺�'Yb³⁺, emit infrared photons of973nm. Sowe achieve the infrared quantum cutting process and improve the solar energyconversion efficiency.2. We successfully prepare GdBO₃:Bi³⁺,Ce³⁺,Yb³⁺nano-powders by thecombustion synthesis method, and through the same methods characterize structureand morphology of the samples. Firstly, we use the light source of973nm to monitorthe excitation of the samples and find that there are two excitation peaks at265nmand360nm. Then we use these two wavelengths as excitation wavelengths toinvestigate the emission spectroscopy of the samples, and the results show thefollowing two energy transitions: Bi³⁺�'Yb³⁺and Ce³⁺�'Yb³⁺, emit infrared photons of973nm, complete the transformation process. Therefore, it improves the infraredcutting quantum conversion efficiency of silicon solar cells.