Research On Structural Optimization And Photoelectric Performance Of Quantum Dot Sensitized Solar Cells

The fossil fuel energy used by mankind has brought progress to our society.But at the same time,due to the significant increase in the demand for energy consumption and the consequent environmental pollution,it has caused irreparable damage to the living environment of mankind.Therefore,"Change the Energy Structure,Protect the Earth"has become a global call and attracted the attention of governments.Energy scientists from various countries have invested in clean and renewable energy research.Solar energy is the most supportive energy technology with development potential among the many renewable energy sources.It is stable and unlimited because solar energy comes from the sun.And there is obvious safety guarantee in terms of overall technical efficiency.In this paper,we have studied quantum dot-sensitized solar cells,which are currently widely concerned,and fabricated solar cell devices with different structures of single and duoble photoanodes.The Ti O₂mesoporous film is prepared with Ti O₂particles at 10～15 nm and used as the electron transport layer of solar cells.Cadmium sulfide/cadmium selenide（Cd S/Cd Se）alloy quantum dots with simple preparation process are selected as the sensitizer.This paper prepared two different morphologies of Cu₂S as counter electrodes on copper mesh in order to explore the influence of Cu₂S morphology on the performance of solar cells.The cell performance of the single photoanode was studied,and then concentrating photovoltaic（CPV）was introduced to improve the light utilization of the cell.The energy loss of light is relatively large when the lower side of the single photoanode structure cell receives light,so the double photoanode solar cell structure was introduced.The more details are as follows:（1）The Ti O₂slurry was prepared by the sol-gel method,and then the Ti O₂slurry was spin-coated on the FTO conductive glass by the centrifugal spin coating method.The FTO glass with Ti O₂slurry was dried in an oven at 60°C,and finally sintered in a muffle furnace to obtain a Ti O₂mesoporous film.In this paper,small particles of10～15 nm Ti O₂were selected as the electron transport layer because small particles of Ti O₂had a larger specific surface area and better light transmittance compared with25nm Ti O₂.A complete photoanode was prepared on FTO glass by depositing Cd S and Cd Se quantum dots and Zn S passivation layer on the Ti O₂film.（2）A wet chemical method was used to prepare particulate Cu₂S on the surface of the copper mesh,and a battery with a single photoanode structure was prepared.The use of Cu₂S/copper mesh composite material as the counter electrode was beneficial to improve the light penetrability of the lower side,and its photoelectric conversion efficiency could reach 2.32%.The photoelectric conversion efficiency could reach 3.59%after the introduction of a light concentrating system.Although the concentrating photovoltaic improved the power conversion efficiency,there was still some energy lost due to the penetration of the counter electrode and the electrolyte.Therefore,we designed a cell with a double photoanode structure to improve the performance of the cell.（3）The preparation method of the photoanode and counter electrode is the same as that of the solar cell with the single photoanode structure in the double photoanode cell structure.Double Ti O₂photoanode design is adopted,which is separated by Cu₂S mesh as the counter electrode.The power conversion efficiency of the double photoanode structure cell can reached 2.64%under the irradiation of parallel light from the upper side.The photoelectric conversion efficiency can reached 8.28%after the introduction of the concentrating photovoltaic.Compared with a battery with a single photoanode structure under normal light conditions,the short-circuit current of the battery surged from 9.76 to 32.297 m A cm^-2.In addition,the influencing factors of the photoelectric performance of the double photoanode structure cell were explored by the comparative experiment of the copper mesh aperture and the thickness of the Ti O₂film on the photoanode.