Quantum Dots Sensitized Solar Cells

In this thesis, the preparation of high-quality water-soluble quantum dots (QDs) and their serving as photovoltaic application were studied.We prepared high-quality oleylamine-capped CdSe QDs with traditional organometalic high temperature heat injection method. After the "ex situ" ligand exchange route, we deposited the water-soluble CdSe QDs on TiO2mesoporous film and achieved a5.4%conversion efficiency for resulting cell devices. The deposition process is very fast and approaches the saturated loading amount within2h. The highest QDs coverage on TiO2with value of34%was obtained.We also prepared inverted type-I CdS/CdSe core/shell structure QDs, which poccess special band alignment. This band alignment favors for the separation of charge carriers, which can improve the short circuit current. A conversion efficiency as high as5.32%was obtained for CdS/CdSe based QDSCs under optimal process conditions.Furthermore, highly luminescent water-soluble type-I Ag2S/CdS core/shell structure QDs were synthesized in aqueous media through a simple and environmental-friendly method, in which acetate salts of silver and chromium, and sodium sulfide were used as Ag, Cd, S precursors, respectively and glutathione (GSH) as capping/stabilizing agents. Various experimental conditions including, the mole ratio of Cd/Ag, Ag/S, Cd/S and the amount of GSH have been systematically investigated in the effects on the optical properties of the as-prepared QDs. In the optimum conditions, we obtained the high stable Ag2S/CdS QDs with the emission wavelength on720nm. Furtermore, the obtained near-infrared emitting Ag2S/CdS would have a potential application value on biological fluorescent labeling and in vivo optical imaging.