| It is significant to optical communication devices with large nonlinear optical propertiesand fast response time. In this paper, we took the CdSeS QDs as research object, preparedCdSeS QDs/Polystyrene(PS) composite film by a spin coating method, anslysed the filmsurface characteristics by X Ray Diffraction(XRD) method and studied optical properties ofCdSeS QDs solution and CdSeS/PS composite film with UV-Vis and fluorescencesprctroscopy testing. The main content of the paper and conclusions are as follows:1. CdSeS/PS composite film have been prepared on quartz substrate(10×10×0.3mm3)by a spin coating method. The thickness of the film can be controlled by adjusting speed ofthe mechine and the time of spin coating. Through the microscope, the thickness of the filmis about10μm. The surface topography of the film was characterized by X Ray Diffraction.In the XRD picture, we can find that there are two diffraction peaks, one in44.4°, anotherin64.1°, corresponding to the diffraction peaks of (220) and (440) diffraction surface. Wecan caculate the size of CdSeS QDs by Scherrer Equation.2. In200-900nm wavelength range of UV-Vis transmittance spectrums of CdSeS QDssolution and CdSeS/PS composite film were measured by double-beam spectrophotometer.The normallized transmittance spectrum demonstrates that absorption peak of the CdSeSQDs is in the523nm position, and the band gap energy is2.37eV. Through the UV-Visspectrum we can get the component of QDs is CdSe0.8S0.2. In the400-700nm wavelengthrange of fluorescence spectrums of the CdSeS QDs solution and CdSeS/PS compostie filmwere measured by fulorescence spectrometer, the photoluminescence peak in537nm postion,compared with UV-Vis spectrum have a15nm stokes shift.3. Their nonlinear optical properties were investigated by Z-Scan method using afemtosecond laser(800nm,50fs,1KHz). The result indicates that CdSeS QDs and CdSeS/PScomposite film have shown the saturated absorption effect, which is due to Two-Photonabsorption(TPA). |
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