Spontaneous Emission Of Semiconductor Quantum Dots In Inverse Opal Photonic Crystals Or Silver Nanoparticles

Since Yablonovitch and John firstly proposed the photonic crystals(PCs) in 1987, the developments and applications of PCs have made considerable progresses. PCs own a periodically varying refractive index, where the propagation of electromagnetic waves has been modulated. Based on this, PCs could create a photonic stop band(PSB) where the propagation of light wave is forbidden. This excellent property of PCs could change the spontaneous emission characteristics of luminescent guests(LG) embedded in PCs, such as organic dyes, quantum dots(QDs) and rare earth ions. Up to now, a series of works in this field have been reported and many interesting phenomena have been observed. metal nanoparticles like Ag, their surface plasmon can couple with light enhance local electric field, which could affect the photoluminescence. Au can effectively improve the photoelectric conversion efficiency of solar cells, and Ag can Improve the LED luminous intensity. In fact, Physical characteristics of light polymer mixed system still needs further research.Generally speaking, the photonic crystal can be divided into two kinds: opal photonic crystals and inverse opals photonic crystals. Compared with opal photonic crystals, inverse opal photonic crystals have wider surface area, thus the application of inverse opal photonic crystal is more broad. As luminescent materials doped in inverse opal photonic crystals, the photoluminescence can be easily control. When the photonic band gap photonic crystal and luminescent material emission band overlap, luminescence properties of luminescent material can be photonic crystals. In luminescent material type, because high fluorescence yield of semiconductor quantum dots, long fluorescence lifetime, the color of the glow of narrow band gap and easy to control, so that the field of semiconductor quantum dots have been people’s attention gradually. We measured by the scanning electron microscope(TEM), to determine the test of the microstructure of the sample. After using the theory of steady transmission spectra and analysis identified the photonic band gap structure of the sample. And then in the regular change of light intensity and temperature conditions, using the steady state emission spectrum experiment, the test samples, a series of spectral analysis data, through the integrated PL(IPLI), PL bandwidth(PLB) and PL Peak(PLP) change rule to qualitative analysis the change of light intensity and temperature to the photonic band gap of doped photonic crystal in SiO2 inverse opal photonic crystals in the photoluminescence quantum dots CdSe control. Results show that under variable temperature, when the CdSe quantum dots into SiO2 inverse opal photonic crystals, SiO2 inverse opal photonic crystal periodic structure of long-short can regulate luminescence properties of quantum dots and damage state of aggregation of quantum dots, and effectively promote the heat exchange of quantum dot with the surrounding environment.For doping CdSe quantum dots of SiO2 inverse opal photonic crystals, we further on its surface coated with a layer of silver nanoparticles, thus further observe quantum dots is control of a series of results. From the experimental data obtained by steady state emission spectrum experiment, silver nanoparticles surface plasmons effect can enhance the intensity of the photoluminescence quantum dot and modulating the emission spectrum of quantum dot shape. Then the regular change of light intensity and temperature conditions based on the analysis of a series of spectral analysis data, such as integrated PL(IPLI), PL bandwidth(PLB) and PL Peak(PLP) to qualitative the Cd Se quantum dots into SiO2 inverse opal photonic crystals with silver nanoparticles which have gained effect.