Preparation Of FeS₂ Electrode Materials And Application It In Dye-sensitized Solar Cells

At present solar energy is considered as the best substitute for fossil energy.As a kind of photoelectric conversion device,the solar cells will be outstanding because of its big development prospects.Solar battery has experienced three generation.The dye-sensitized solar cell has drawn great scientists' attention due to short period of fabrication and process simplification.Dye-sensitized solar cell is consist of four sections including photo-anode,electrolyte,dyes and counter electrode.The counter electrode plays a great role in raising the photoelectric conversion efficiency.Generally,the electrode material is mental platinum,which is expensive at the cost of production restricting the industrialization development of the DSSC.Ferrous sulfide(FeS2)in semiconductor photovoltaic systems is a kind of material which is rich in reserves and high practicability.In this paper,we choose a hydrothermal method to fabricate pure ferrous sulfide and ferrous sulfide doped ultra-long carbon nanotubes.They will be applied in DSSC.We also study the synthesis factors of ferrous sulfide.Here are the concrete experimental plans:(1)We choose hydrothermal method to synthetize the pyrite and study the six control factors of synthesizing ferrous sulfide,including the iron and sulfur source at a different molar mass,NaOH concentration,dosage of surfactant PVP,packing ratio,hydrothermal time and hydrothermal temperature.The best preparation conditions were obtained,as showed below:the iron and sulfur source was 1:6 at molar mass,dosage of surfactant PVP is 0.4 gram,Reaction solution pH is 8,packing ratio is 70%,hydrothermal time is18h,hydrothermal temperature is 180?.(2)Ferrous sulfide was made as counter electrode applying in DSSC.DSSC's power conversion efficiency(PCE)is 2.53%.At the same time,we analyze molecular surface state by the photovoltage characterization.Ferrous sulfide was doped by ultra-long carbon nanotubes,which was indicating the fact that the PCE of FeS2 doped CNTs is 30%higher than the pure FeS2.By fitting the electrochemical impedance spectra can be learned that the addition of carbon nanotube fibers reduces the series resistance of the battery and increases the carrier rate.(3)We research on electrochemical properties of ferrous sulfide doped by different amount carbon nanotubes.By means of electrochemical performance test,we can know that solar cells have the greatest photoelectric conversion efficiency about 4.03%when the mass fraction of doping carbon nanotubes into 1 wt%Specifically speaking,the open circuit voltage is 0.62 V,the short circuit current density is 10.16mA/cm2 and the fill factor is 0.64.Compared with ferrous sulfide counter electrodes of other doping amounts,the 1wt%doped amount has the smallest Nernst diffusion resistance.At this time,the ferrous sulfide can also have the highest electrochemical catalytic activity.Doping carbon nanotubes can make up for the defect of ferrous sulfide on the surface of the domain.