Investigation Of The Counter Electrode Based On Metal Sulfide In Quantum Dot Sensitized Solar Cells

As an inexhaustible renewable energy,solar energy is regarded as the most vital and reliable clean energy to solve the increasing energy demand.In order to efficiently collect and utilize solar energy,various noble solar cell devices have been studied.As one of the representatives of the third generation of solar cells,Quantum dot sensitized solar cells(QDSSCs)have good thermal stability and humidity stability,and become one of the solar cells with development potential due to the band gap of the quantum dots(QDs)can be accommodative and unique light properties such as the quantum tunable energy band gaps effect and other advantages.As one of the crucial components of Quantum dot sensitized solar cells,the counter electrode(CE)is responsible for collecting electrons transmitted from the external circuit and reducing the multi-sulfur electrolyte.Therefore,the conductivity,stability and catalytic activity of the CE directly affect the photoelectric performance of QDSSCs.Metal sulfide has excellent catalytic activity and good electrical conductivity,and has been widely used in the research of Quantum dot sensitized solar cells counter electrode materials.However,the poor stability of metal sulfide in polysulfide electrolyte limits its application.Therefore,it is the focus of current research to prepare metal sulfide pair electrodes with strong conductivity,good stability and high catalytic activity.In this paper,the main contents of this paper are summarized as follows:(1)Carbon nanoparticle CE was prepared by scraping coating method and Co S CE by chemical bath deposition method(CBD).The influence of annealing treatment on specific surface area of carbon material and the stability of the pair electrode in redox reaction were investigated.The Co S electrode materials with dense surface and suitable specific surface area were obtained by changing the deposition time of chemical bath.Through the systematic analysis of the advantages and disadvantages of the two counter electrode materials,it can be seen that Co S as the counter electrode can effectively improve the open circuit voltage(Voc)of the cell,and the photoelectric conversion efficiency(PCE)of the cell is improved by 60%.(2)CuS CE was prepared by chemical bath deposition as the counter electrode of full spectrum liquid junction QDSSCs.Adjusted the wavelength range of sunlight incident from CuS side to the cell.When the full-spectrum light is irradiated into the photoanode,it is reflected by the parabolic mirror,and then incident on the cell from one side of the counter electrode.A filter is placed on the CE to divide the light into ultraviolet visible light and near-infrared light.The influence of different range of sunlight(including no light,UV-visible light,near-infrared and full-spectral light)on the QDSSCs performance was studied.The unique properties of CuS nanomaterials and the adjustment of device structure optimize the overall photovoltaic performance of QDSSCs.The champion photoelectric conversion efficiency of the cell is 5.6%under the condition of double-side full-spectrum sunlight incident,of which Jsc is 21.7 m A cm^-2,Voc is 0.56 V,and FF is42.8%.(3)CuS/PbS composites CE with high energy band matching degree were prepared by chemical bath deposition and successive ionic layer adsorption and reaction method(SILAR).The growth of PbS nanoparticles on CuS was regulated by changing the deposition times of SILAR(0?4C)to avoid agglomeration caused by excessive PbS content.First,the morphology and structure of CuS/PbS composite were measured and analyzed,then the photovoltaic and electrochemical properties of QDSSCs assembled by CuS/PbS composite electrode were tested,and various parameters of CuS/PbS composite electrode of SILAR deposition times were comprehensively compared and analyzed.Finally,the values of Jsc,Voc,FF,and PCE increased from 17.98 m A cm^-2 to 19.43 m A cm^-2,0.53 V to 0.56 V,31.62%to 31.71%,and 3.01%to 3.48%.