Investigation The Effect Of Passivation Layer Decorated TiO₂ Photoanodes On Performance Of Quantum Dots Sensitized Solar Cells

Due to the excessive consumption of fossil fuels,environmental problems and energy shortage have become a common concern in the world.Solar energy has become one of research hotspots because of its pollution-free,safe,renewable and clean characteristics.Quantum dot-sensitized solar cells?QDSSCs?developed from the third generation of dye-sensitized solar cells have a high theoretical photoelectric conversion efficiency,but the actual power conversion efficiency is far from the theoretical conversion efficiency due to interface structure problem.In this paper,the research of photoanode of QDSSCs is focused on optimizing the surface structure of TiO₂ to improve the photoelectric performance of solar cells.CuS and MnS were prepared as passivation layer to modify the TiO₂ photoanode,and TiO₂ with different morphologies are used to improve the structure of photoanode.The photoanode was adjusted by systematic experiments to achieve the optimal performance.It provides an experimental reference for the study of photoanode of quantum dot sensitized solar cells.The specific research contents and results of this paper are as follows:?1?Preparation of nanosheets?NS?by hydrothermal method.Mesoporous TiO₂ film was prepared by spin-coating method using nanosheet and nanoparticle?NP?structures.The CuS passivation layer prepared by successive ionic layer adsorption and reaction?SILAR?method on TiO₂,CdS/CdSe co-sensitization and ZnS passivation modified quantum dot sensitizer to form photoanode,assembled into a cell with polysulfide electrolyte and CuS counter electrode.By changing the thickness of the passivation layer to adjust the cell performance to find the best ratio.Meanwhile,study the morphology and structure of the material.The deposition of CuS can passivate the surface defects of TiO₂and effectively suppress the hole electron recombination.The power conversion efficiency?PCE?of TiO₂ NS/CuS/QDs QDSSCs reached 4.71%,which was much higher than that of QDSSCs?3.91%?without deposition of passivation layer.The efficiency of assembling a cell based on TiO₂ NP as a photoanode was 4.61%,because the electron transport efficiency of TiO₂ NSs of{001}crystal plane is higher than that of NPs.?2?The MnS passivation layer was prepared by SILAR method.The quantum dots were deposited on two different titanium dioxide nanostructures?NS or NP?to form TiO₂/MnS/CdS/CdSe/ZnS photoelectrode,which was assembled into a cell with electrolyte and counter electrode.Since MnS as the passivation layer to remove the surface defects of TiO₂ and increase the injection amount of electrons from the quantum dots to the TiO₂conduction band,the short-circuit current of the cell is remarkably improved,thereby improving the photoelectric conversion efficiency of the cell.The experimental results show that the short-circuit photocurrent(J_sc)of TiO₂ NS assembled into QDSSCs increases from 17.131 mA/cm² to 21.198 mA/cm²,and the PCE increased from 3.92%to 5.01%.The J_sc of TiO₂ NP assembled into QDSSCs increased from 15.711 mA/cm² to 19.968 mA/cm²,and the PCE increased from 3.83%to 4.85%.?3?The nanosheets prepared by hydrothermal method were grown on FTO conductive glass.The rutile TiO₂ nano-branched arrays were grown on nanosheets by chemical bath deposition,and their morphology and photoelectrochemical properties were observed and characterized.Because the nanosheets in the composite structure still maintain good electronic conductivity and the branch structure improves the quantum dot adsorption and light collection efficiency,the performance of TiO₂ NS/TiCl₄/QD cell increased from 3.92%to 4.07%compared with the cell without TiCl₄ deposition.With the deposition of MnS passivation layer,the surface of TiO₂ composite structure was optimized.Therefore,the highest PCE result was 5.2%from the TiO₂ NS/TiCl₄/MnS/QD cell in the experiment.