Study On Preparation And Properties Of ZnSe Quantum Dots Sensitized Nano-TiO₂ Solar Cells

The scientific community has always been committed to the research and development of a variety of new energy sources,especially solar cells are the most concerned,because solar energy is both clean energy and inexhaustible.Among them,quantum dot sensitized solar cells,which are third-generation solar cells,are favored for their high theoretical conversion efficiency.However,the actual conversion efficiency of the quantum dot sensitized solar cell still has a large room for improvement compared with the theoretical value.Based on the concept of environmental protection,this paper designs and prepares a solar cell with ZnSe quantum dot-sensitized mesoporous nano-titanium dioxide film as photoanode,and studies and tests the photoelectron characteristics of the photoanode and the performance of the solar cells.In this paper,La-doped mesoporous nano-TiO₂ powder was prepared by Sol-gel method,and TiO₂ film was prepared by knife coating method.The ZnSe/ZnS/Ligans core-shell quantum dots were synthesized by low temperature aqueous phase method,and the quantum dot sensitized nano-TiO₂ film was prepared by chemical bath deposition?CBD?.TiO₂ powder,TiO₂ film and sensitized TiO₂ film were characterized by XRD,X-ray photoelectron spectroscopy?XPS?,BET isotherm adsorption,UV-VIS absorption spectroscopy,SEM,SPS and EFISPS technology.The results of XPS valence band spectrum show that the conduction band bottom of ZnSe quantum dots is located at-0.95V,which is very suitable as a sensitizer to broaden the absorption range of TiO₂ film.SEM and Raman spectroscopy confirmed that the ZnSe quantum dots were successfully loaded onto the surface of the TiO₂ film by the CBD method.In addition,it was confirmed by UV-VIS absorption spectroscopy that the optical band gap of the sensitized film was 2.14eV,which was remarkably reduced with respect to 2.9 eV of the TiO₂ film before sensitization.In this study,a ZnSe quantum dot sensitized nano-TiO₂ film was used as a photoanode,Cu₂S was used as a counter electrode,and a polysulfide electrolyte(S^2-/S_n^2-)was used as an electrolyte to prepare a solar cell with a"sandwich"structure.By optimizing the ligand and electrolyte,the photoelectric conversion efficiency of the battery was increased from the initial 0.01%to 0.037%.UV-VIS absorption spectroscopy and transient photovoltage spectroscopy?TPS?results show that the band gap of Mn²⁺doped ZnSe quantum dot sensitized film is further reduced to 1.61eV,and the lifetime of photogenerated carriers is increased by 4.7 times.The J-V curve shows that the efficiency of the Mn²⁺doped ZnSe sensitized solar cell is 2.6times higher than that of the undoped cell.In view of the loss of quantum dots in water-based electrolytes,the authors adopted the method of introducing CdS block layer,and found that when the block layer is six layers,the performance of the battery is the best,and the optimal conversion efficiency is 3.73%.In order to improve the electron recombination of FTO-TiO2 interface,the author introduced a TiO₂ compact layer at the interface,and the filling factor of the battery increased to 69.9%.On this basis,the conversion efficiency of the battery also reached the maximum value of this paper-4.38%.