Preparation And Photovoltaic Performance Of Mesoporous TiO₂-based Sensitized Solar Cells

In the third generation of solar cells,sensitized solar cells have been widely studied because of their advantages of simple preparation,low cost and high theoretical efficiency.Although the research on sensitized solar cells has achieved fruitful results,there are still some problems,such as low light absorption efficiency and serious interface charge recombination,which seriously restrict the improvement of the performance of sensitized solar cells.Therefore,it is of great significance for the research and development of high-performance photovoltaic devices to enhance the light absorption of sensitized solar cells and restrain the interface charge recombination.The research work of this paper mainly includes:（1）In order to improve the light absorption efficiency of dye-sensitized solar cells（DSSCs）,a novel UCPs-TiO₂ composite photoanode film was designed using commercial upconversion phosphors（UCPs）with wide size distribution.The results show that the introduction of UCPs can significantly improve the light absorption efficiency of DSSCs.On the one hand,commercial UCPs with wide size distribution improve the light scattering ability of photoanode.On the other hand,it benefits from the unique upconversion mechanism of UCPs.At the same time,although UCPs@TiO₂ core-shell structure was formed by TiCl₄ post-treatment,the presence of UCPs still intensifies the photoanode/electrolyte interface charge recombination.The results show that when the mass percentage of UCPs in the photoanode is about 15%,the photoelectric conversion efficiency of the corresponding device reaches 7.17%,which is about 32%higher than that of the device based on pure TiO₂ mesoporous film（5.45%）.（2）In order to inhibit the interfacial charge recombination of all solid-state quantum dot sensitized solar cells（QDSCs）,the Pb²⁺and Cd²⁺mixed cationic precursor solutions were used to realize the synchronous deposition of PbS and CdS quantum dots（QDs）by simple successive ionic layer adsorption and reaction（SILAR）,and the efficient and stable all solid-state QDSCs were constructed.The results show that the synchronous deposition of CdS and PbS QDs has the following two advantages:（1）The synchronous deposition inhibits the excessive growth of PbS QDs in TiO₂ mesoporous films,and the decrease of the size of QDs causes the conduction band energy level to move up,thus accelerating the separation of photogenerated carriers at the interface;（2）Synchrodeposition passivates the high density defects on the surface of PbS QDs and inhibits interfacial charge recombination.Finally,the device performance based on（Pb,Cd）S QDs（0.32%）is about 5 times better than that based on PbS/CdS QDs（0.06%）.