Fabrication And Optimization Of The Mesoporous TiO₂ Photoanodes For Quantum Dot Sensitized Solar Cells

Quantum dot sensitized solar cells（QDSCs）, the third generation of photovoltaic cell, have attracted extensive research attention. Up to now, the highest photoelectric conversion efficiency of QDSCs is far behind the theoretical conversion efficiency. How to further improve the photoelectric conversion efficiency have been becoming the current hot research hotspots.In this artice, TiO₂ was used as photoanode materials and countelectrode was CuS/FTO which was made by a CBD method, Polysulfide electrolyte was injected into the cell. We study the energy conversion efficiency of CdS QDs、PbS QDs and carbon QDs sensitized solar cells. We optimized the energy conversion efficiency of QDSCs and microwave synthesis of CQDs sensitized the photoanode for the first time. The main work of this paper is as follows:1、The mesoporous TiO₂ films are fabricated on conducting glasses by spin coating,and the film thickness is controlled by spin coating times. The CdS quantum dot sensitizers on mesoporous TiO₂ films are prepared by successive ionic layer adsorption and reaction method. We investigated the dependence of energy conversion efficiencies on the different deposition times and found that the best performance occurs at 9 cycles of CdS QDs deposited on TiO₂ films. On this basis, the repetitive coating times of TiO₂ is studied. The results demonstrate that the best short circuit photocurrent（8.18 mA·cm-2） and efficiency（2.32%） are obtained by the cell with three time spin coating of TiO₂ and the 15 μm thickness.2、PbS QDs-sensitized on mesoporous TiO₂ films prepared by using the successive ionic layer adsorption and reaction method and found that the best energy conversion efficiencies（1.6%） occurs at 2 cycles of PbS QDs deposited on TiO₂ films. Based on the optimal deposition times of PbS quantum dots, we fabricated PbS QDs and CdS QDs co-sensitized solar cells and acquired best efficiencies when sensitized CdS QDs for 5 cycles. The results demonstrate that the efficiency of PbS QDs and CdS QDs co-sensitized solar cell are better than CdS QDSCs and PbS QDSCs.3、We reports on a good stability, uniform in size, and well water-soluble carbon quantum dots（CQDs） which were successfully fabricated by microwave method. CQDs/TiO₂ photoanodes were prepared via immersing TiO₂ mesoporous films in CQDs solution. We investigated the performance of CQDs sensitized solar cells and pristine TiO₂ solar cells. The energy conversion efficiency of CQDs sensitized solar cells is 2.2 times of pristine TiO₂ solar cells. This study puts forward a new train of thought of microwave synthesis carbon quantum dots combined with mesoporous TiO₂ films, and the results show that the carbon quantum dots is introduced into helps to improve the photoelectric conversion efficiency of solar cells.