The Preparation Of CuInS₂and Its Application In Dye-sensitized Solar Cells

In this thesis, chalcopyrite and wurtzite copper indium sulfide （CuInS₂） were prepared by a facilesolution route. In the proposed preparation route, acetylacetonate was used as precursor,1-dodecanethiol（DDT） or component solvent [oleylamine （OLA） and DDT] was used as solvent. The factors, includingreaction time, reaction temperature, concentration of precursors and the relative amount of OLA incomponent solvent, which influence the morphology, size and oriented growth of the CuInS₂nanocrystals（NCs） were studied in details. Ligand exchanged approach was used to exchange the organic ligands on thesurface of the CuInS₂NCs to inorganic ligands without change the good distribution of the CuInS₂NCs.The characterizations showed that this ligand exchanged routes can replace the traditional high temperaturepyrolytic cracking methods to remove the organic ligand on the surface of the NCs. Based on ligandexchanged CuInS₂counter electrode （CE）, the power conversion efficiency of the dye-sensitized solar cells（DSSCs） was tested. The result showed that the conversion efficiency of DSSCs increased obviously afterthe organic ligand capped CuInS₂NCs were exchanged to inorganic ligand, and the ligand exchangedCuInS₂counter electrode （CE） has potential to replace the Pt CE.This thesis includes the following main aspects:（1） Firstly, pure monodisperse wurtzite CuInS₂NCs were obtained by a simple one-pot method,which possess special shape with good size distribution. Then, the influence of the OLA on the growth ofthe CuInS₂NCs was studied through comparing with or without the addition of the OLA. The result of thecharacterizations showed that the OLA influenced the optical property of the CuInS₂NCs by influencingthe crystal structure, component, shape and size distribution of the CuInS₂NCs.（2） The size of the CuInS₂NCs was controlled by varying the reaction time and temperature ofthe experiment. Time-dependent experiments were performed to observe the growth of CuInS₂NCs. Afteradjusting the relative amount of the DDT and OLA, the oriented growth of the CuInS₂NCs were studied.（3） Using ligand exchanged approach, we treat the CuInS₂NCs solution with （NH4）2S and changethe CuInS₂NCs from hydrophobic to hydrophilic. The characterizations showed that the organic ligands onthe surface of the CuInS₂NCs were exchanged to inorganic ligands S₂-successfully. Moreover, the intensity of the UV-vis of the ligand exchanged CuInS₂NCs increased obviously.Based on ligand exchanged CuInS₂CE, the power conversion efficiency of the dye-sensitizedsolar cells （DSSCs） was tested. The result showed that the conversion efficiency of DSSCs increased by17times after ligand exchanged. Interestingly, the conversion efficiency of DSSCs based on inorganic ligandcapped CuInS₂NCs is also higher than that of organic ligand capped CuInS₂NCs film with sinteringtreatment. The inorganic ligand capped CuInS₂NCs film CE gave a similar conversion efficiency with thatof Pt CE. This kind of ligand exchanged process could replace the traditional high temperature pyrolyticcracking methods, and the inorganic ligand capped CuInS₂NCs film CE could act as a substitute of the PtCE.