Study On The Spectral Properties Of Quantum Dots

With the large consumption of the traditional energy, people have been attracteda great attention by the solar energy. They are searching for a photovoltaic powergeneration material whose generating cost could be as low as fossil for a long time,because the generating efficiency of present ones is poor. And quantum dots bringhope for this kind of research. Besides, since their unique characteristics, quantumdots have expansive prospect of applications in the fields of optics, electronics,medicine and so on.The quantum dots are also called nanocrystals. When the size of semiconductingmaterial reaches the nanometer grade, the charge carriers in the material will beconfined in a very limited area in three dimensions, which causes the energyquantized, and the nanocrystals will show distinct quantum effect. That is the reasonwhy they is called quantum dots. This paper is based on the special characters ofquantum dots, studies the absorption and fluorescence spectral properties, analyzesthe reason of the drifting of spectrum, and checks it through the experiments.Moreover, we introduce the common-used spectrometers in the analysis of quantumdots, such as UV-visible-infrared spectrometer, fluorescence spectrometer and so on.PbSe quantum dots were synthesised in oil phase, the as-prepared particles haveeven size and good dispersibility. Measuring the PbSe quantum dots with differenttemperature and hours, we have observed the drifting phenomenon of the absorptionand fluorescence spectrum, which was in accord with the theoretical derivation: withthe reduction of the particle size of quantum dots, the absorption and fluorescenceemission shift to shorter wavelength; and with the increase of the reacting time andtemperature, they shift to longer wavelength subsequently.ZnO quantum dots were prepared by the sol-gel method, it was observed that thesize of the particles synthesized at room temperature was large, while the onessynthesized at0℃was smaller. They were measured by TEM, XRD, UV-visibleabsorption spectrum and fluorescence spectrum, and the fluorescence in the visible region was analyzed.In the last place, we introduce the colorimetry, which includes the basic concepts,relevant theories and calculation method of it. As for the fluorescence in the visibleregion, the chrominance were studied on the basis of colorimetric principle, the colorcoordinate and color temperature were calculated, and the results were checkedthrough the actual luminous effects as well.