The Fabrication And Photoelectric Properties Of CdSe/CdS Quantum Dots Film

Based on the predominant properties of quantum dots, CdSe/CdS quantum dots was synthesized in organic phase. Then the CdSe/CdS quantum dots films were fabricated on ITO through Layer-by-layer electrostatic self-assembly technology. The self-assembled conditions and fluorescence properties of quantum dots ultrathin films were studied carefully, and the application of ultrathin films in modified electrode was reviewed. The purpose of this paper is to achieve the sensor of quantum dots ultrathin films with good photoelectricity properties. The major work consists of parts as follows: Synthesize of CdSe/CdS QDs: CdSe and CdSe/CdS quantum dots weresynthesized in organic and aqueous phase. The obtained quantum dots were characterized with transmission electron microscopy (TEM) and spectrofluorimetry. The results showed that the fluorescent intensity and stability of CdSe/CdS quantum dots are more stronger than CdS(or CdSe) quantum dots. What is more, compared to quantum dots synthesized in aqueous phase, the fluorescent intensity of quantum dots synthesized in organic phase is more stronger, the half band breadth is narrower, and the symmetry of peak is better.Assembly of CdSe/CdS ultrathin films: firstly, the CdSe/CdS quantum dots synthesized in organic phase was modified by 2-mercaptoacetic acid, then it was made into ultrathin films on ITO substrate by Layer-by-layer electrostatic self-assembly technology. The results showed that CdSe/CdS QDs dissolved in NH4Cl (pH=6) solution had good photoluminescence properties and good quality when it was maded into ultrathin films .The Multi-layer films of CdSe/CdS QDs and Fluorescence influence factor: the Multi-layer film was obtained by Layer assembly technology. The results showed that there is a 1inear relationship between the fluorescence intensity and the layer numbers of the thin films,indicating that the resultant nanofilms had good quality. Nitrogen ?enhanced the fluorescence intensity of the thin films and air or oxygen lowered the fluorescence intensity of the thin films. This phenomena indicated that this film was sensitive to gas, so this film maybe made into gas sensor in the future.The application of ultrathin films in modified electrode: The CdSe/CdS quantum dots was assembled onto the surface of glass carbon to obtain CdSe/CdS /PDDA/GC. The electrochemistry and electrocatalysis of this modified electrode were characterized by CV curves. The results showed that this electrode had good reaction toward NO2- in PBS solution(pH=7.0). The electrode reduced oxidation overpotential, which indicated that the QDs film played a very good electrocatalytic activity.