Applied Research Of Porous Carbon-based Counter Electrode In Quantum Dot-sensitized Solar Cells

Carbon materials have the advantages of low cost,good conductivity,large specific surface area and good long-term stability.They are one of the ideal materials for counter electrodes of quantum dot-sensitized solar cells.Metal-organic framework materials（MOFs）are porous materials with high specific surface area formed by the ordered coordination assembly of metal ions and organic ligands in three-dimensional space.They are one of the ideal precursors for the synthesis of carbon-based materials.In this study,MOFs were used as precursors to synthesize porous nitrogen-doped carbon composites CoSe₂-NC and NiS₂-NC for the counter electrodes of quantum dot-sensitized solar cells.XRD,Raman,SEM,BET,XPS and other technologies were used to test the structure,morphology,and chemical composition of materials,and EIS,Tafel,CV and other electrochemical tests were used to study its electrocatalytic activity.Finally,a quantum dot-sensitized solar cell is assembled and the photovoltaic performance is tested.First,cobalt-based metal organic framework material zif-67 was synthesized at room temperature.Nitrogen-doped porous carbon material doped with cobalt metal particles was prepared by pyrolysis in an argon atmosphere at 800℃.The selenization reaction was carried to obtain a composite material CoSe₂-NC.CoSe₂and nitrogen-doped porous carbon NC were also prepared as comparison materials.Due to the more catalytically active sites and the mesoporous structure that facilitates the diffusion of polysulfide electrolytes,electrochemical tests show that CoSe₂-NC has higher catalytic activity for polysulfur electrolytes than CoSe₂and NC,and it’s charge transfer resistance（Rct）is 3Ω·cm^-2.In addition,the nitrogen-doped porous carbon not only has a certain catalytic activity,but also increases the charge transfer rate between the external circuit and the CoSe₂particles.Finally,the power conversion efficiency（PCE）of CdS/CdSe QDSCs assembled based on CoSe₂-NC counter electrodes was 5.06%.Secondly,NiS₂-NC was obtained by carbonization and vulcanization of the synthesized Ni-MOFS.NiS₂-NC,a porous nickel carbon composite,was obtained,and NiS₂and porous carbon NC were prepared for comparison.Due to more catalytically active sites and a mesoporous structure that facilitates the diffusion of polysulfide electrolytes,electrochemical tests have shown that the NiS₂-NC counter electrode has higher catalytic activity than NiS₂and NC for polysulfide electrolytes,and it’s charge transfer resistance（Rct）is 7.6Ω·cm^-2.The power conversion efficiency of the CdS/CdSe QDSCs assembled based on the NiS₂-NC counter electrode was 4.93%.Finally,glucose-derived porous carbon was prepared by hydrothermal method and chemical activation of potassium hydroxide.The material exhibited a layered porous structure of macropores,mesopores and micropores.The photoelectric conversion efficiency of CdS/CdSe QDSCs was 5.61%.Through EIS,CV,and Tafel polarization tests,it was found that the counter electrode made of glucose-derived porous carbon showed excellent catalytic activity for polysulfide electrolytes.The experimental results show that glucose-derived porous carbon materials can be potential low-cost counter electrode materials for QDSCs.