Preparation And Sensitization Of CuInS₂-based Quantum Dot Solar Cells

Quantum dot materials have the characteristics of quantum limiting effect,tunneling effect and multi-exciton effect.The theoretical photoelectric conversion efficiency of solar cells with quantum dots as sensitizer is up to 44%.Compared with the traditional binary compound containing heavy metal elements,CuInS₂ quantum dots have the advantages of adjustable band gap,high light absorption rate and no toxic elements,so it is more suitable for sensitizer of quantum dot solar cells.In this paper,CuInS₂ and Zn doped CuInS₂ quantum dots were prepared by organic thermal injection method.The quantum dots adsorbed TiO₂ thin films to form the photoanode of sensitized battery.Using XRD,SEM,XPS,TEM and PL spectra,ultraviolet-visible absorption spectrum analysis methods,such as quantum dots were studied and the light anode crystal structure,morphology,ionic valence,light absorption and electrochemical impedance characteristics,analyzes the microcosmic structure of quantum dots control factors,combined with the battery J-V discusses the photoelectric properties of optimizing conditions and regulatory mechanism,The main results are as follows:(1)The effects of heat injection reaction temperature on the crystalline,particle size and optical band gap of CuInS₂ quantum dots were studied.It was found that with the increase of reaction temperature,the particle size of CuInS₂ quantum dots increased,the optical band gap became smaller,and the crystallization property and light absorption rate were improved.When the reaction temperature is 170?,no impurities are formed,the particle size is 3.9 nm and the optical band gap is 2.28e V.The TiO₂ substrate has the highest load,which is suitable for use as the light absorption layer of solar cells.(2)Zn-CuInS₂ alloying quantum dots were formed by Zn²⁺doping,and the influence of Zn doping concentration was studied.It was found that with the increase of doping concentration,the peak of XRD showed red shift.The particle size changed little,and the emission peak of PL showed red shift and the peak increased.Zn doping inhibits carrier recombination,enhances the photoelectron conversion rate and electron life,and improves the photoelectric conversion efficiency of photovoltaic devices.(3)The ligand molecule 3-mercaptopropionic acid(MPA)was selected as the surface ligand of the quantum dots by the method of ion ligand exchange.The photoanodes prepared under different conditions were studied,including pH value of solution,deposition temperature,deposition time and concentration of free ligand.The photoanodes were synthesized into quantum dot sensitized solar cells,and the photoelectric conversion efficiency of the devices was 2.90%.