| Summary: | 碩士 === 國立成功大學 === 化學工程學系碩博士班 === 96 === In this study, cadmium sulfide (CdS) and cadmium selenide (CdSe) quantum dots (QDs) were used as sensitizers of dye-sensitized solar cells (DSSCs). This two QDs were sequentially assembled onto a nanocrystalline TiO2 film, using a chemical bath deposition (CBD) process, to prepare a CdS/CdSe co-sensitized photoelectrode for QDs-sensitized solar cell application. The effects of CBD cycles and the positions of QDs respected to TiO2 on the performance of QDs-DSSCs are studied. The results showed that CdS and CdSe QDs have complementary effect in the light harvest, but the performance of a QDs co-sensitized solar cell is strongly dependent on the order of CdS and CdSe respected to the TiO2. In the cascade structure of TiO2/CdS/CdSe electrode, the alignment of the Fermi level between CdS and CdSe forms a stepwise structure of band-edge levels which is advantageous to the electron injection and hole-recovery of CdS and CdSe QDs. An energy conversion efficiency of 2.48% has been achieved using a ITO/TiO2/CdS(3)/CdSe(4) electrode. Besides, we deposited Zinc sulfide (ZnS) QDs onto the TiO2/CdS/CdSe electrode. The experimental results showed that ZnS can avoid the occurrence of leakage current and increase photostability. An energy conversion efficiency of 3.88% has been achieved in this study using a ITO/TiO2(13.55μm)/CdS(3)/CdSe(4)/ZnS electrode.
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