| Quantum dot sensitized solar cells exhibiting significant advantages, such as high molar extinction coefficient, tunable spectral response range and extremely high theoretical conversion efficiency, etc, have received tremendous attention in the research of solar cells field. In the thesis, the effects of experiment parameters of SILAR on the deposited morphology and properties of the products have been studied. The research also has highlighted the effect of reaction temperature on the performance of TiO2 thin film. On this basis, the optical and photoelectric conversion properties of PbS and CdS quantum dots (QDs) co-sensitized TiO2 thin film have been researched. The main results of this study are as follows:(1) TiO2 thin films were deposited by a high vacuum multifunctional magnetron sputtering equipment using TiO2 ceramic targets on Ti substrates. The effects of experiment parameters on the distribution and dimension of QDs deposited by successive ionic layer adsorption and reaction (SILAR) on TiO2 film were characterized by SEM and particle size distribution analysis. The research results show that, in every SILAR preparation period, it includes the growth of QDs crystal nucleus and the nucleation of new QDs; It is found that the concentration of Pb+ has a significant effect on the density of quantum dot; With the increasing of reaction temperature, the dimension of quantum dot first decreased and then increased; The sizes of quantum dots prepared with ultrasonic-assisted method in the process of depositing were relatively concentrated with the mainly size located at 6-7nm.(2) Heat-assited PbS/TiO2 thin films with different reaction temperatures were prepared. Microstructures, optical and photoelectron-chemical properties of the as-synthesized thin films were investigated systematically. For the PbS/TiO2 thin films with reaction temperature changing from 10 to 95 ℃, PbS particles obtained by successive ionic layer adsorption and reaction are galena phase. In addition, the absorption edges of the samples exhibited the red shift and the band gap values decreased from 3.58 to 2.88eV with.the introduction of PbS quantum dots. What’s more, the photovoltaic current is greatly increased by the addition of PbS quantum dot. However, excessive amounts of quantum dot will increase the odds of the recombination of carriers. which lead to obstructed channels for electron, so Ti/TiO2/PbS films prepared at 60℃ have highest photocurrent intensity. Besides that. the increasing of QDs is conducive to improving the photocatalytic activity of TiO2 film using the solution of methyl orange as simulating pollutant.(3) The low temperature hydrogen peroxide oxidation method has been adopted to produce porous TiO2 films. And SILAR method has been adopted to prepare PbS and CdS co-sensitized TiO2 thin films. Specifically, QDSSCs consistsing of QDs/TiO2 thin films for photoanode, Pt for counter electrode and more sulfur electrolyte for electrolyte to assemble QDSSCs were studied. It is found that CdS than PbS sensitized TiO2 thin films have superior performance. There will have rearrangement of energy among PbS、CdS and TiO2. TiO2/CdS/PbS construction with stepwise band edge is good for rapid transmission of charge carrier and improvement of photoelectric conversion characteristic. Moreover, we have researched the function of catalytic active of films with methyl orange solution as simulated pollutants. The result indicate that PbS get better photocatalytic performance than CdS sensitized TiO2 thin film, especially the film with TiO2/CdS/PbS structure get the first place. |
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