Synthesis And Photoelectric Properties Study On The Surfactant-free CuInS₂Nanocrystals

Nowadays, With the continuous development of society, traditional fossil fuels are depleted,looking for new renewable energy has become more important. Solar cells have attracted great attention asone of new energies for its rich source, cheap and clean in recent years. Among numerous types of solarcells, the CuInS2thin-film solar cell has attracted great interest due to its low cost, fine stability and highpower conversion efficiency. CIS is called " a very promising new thin film solar cell material of the nextera". Currently, methods of preparing CIS thin film are various, among the proposed preparation route,copper indium sulfide (CuInS2) were prepared by a facile solution route.In this thesis, chalcopyrite copper indium sulfide were prepared by a facile solution route. In theproposed preparation route, CuCl and In(ac)3were used as precursor,1-dodecanethiol (DDT) or componentsolvent [Octadecene (ODE) and DDT] was used as solvent. Ligand exchanged approach was used toexchange the organic ligands on the surface of the CuInS2NCs to inorganic ligands without transform thegood distribution of the CuInS2NCs. The characterizations demonstrated that this ligand exchanged routescan take the place of the traditional high temperature pyrolytic methods to remove the organic ligand on thesurface of the NCs. Based on ligand exchanged CuInS2counter electrode (CE), the power conversionefficiency of the dye-sensitized solar cells (DSSCs) was tested. The result illustrated that the conversionefficiency of DSSCs increased obviously after the organic ligand removed, and the ligand exchangedCuInS2counter electrode (CE) has potential to replace the Pt CE. At last, CuInS2thin film solar cells wereattempted to be assembled. Different methods were applied to prepare Mo back contact, CdS buffer layer,i-ZnO/ITO window layer, Al contact. Then the thin film solar cells were assembled and the I-V tests were performed. We also explorate some deposition conditions of CdS buffer layer, such as, pH, depositiontemperature, deposition time, and get the optimal conditions.This thesis includes the following main aspects:(1) In the chapter2, pure monodisperse chalcopyrite CuInS2NCs were obtained by a simpleone-pot method, and we compared the difference of two synthetic pathways. the crystal structure,morpHology, components, homogeneity and dispersibility of CuInS2are all different.(2) In the chapter3, Using ligand exchanged approach, we treat the CuInS2NCs solution with(NH4)2S and change the CuInS2NCs from hydropHobic to hydropHilic. The characterizations showed thatthe organic ligands on the 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 onligand exchanged CuInS2counter electrode (CE), the power conversion efficiency of the dye-sensitizedsolar cells (DSSCs) was tested. The result illustrated that the conversion efficiency of DSSCs increasedobviously after the organic ligand removed, and The inorganic ligand capped CuInS2NCs film CE gave asimilar conversion efficiency with that of Pt CE. This kind of ligand exchanged process could replace thetraditional high temperature pyrolytic cracking methods, and the inorganic ligand capped CuInS2NCs filmCE could act as a substitute of the Pt CE.(3) In the chapter4, CuInS2thin film solar cells were attempted to be assembled. Differentmethods were applied to prepare Mo back contact, CdS buffer layer, i-ZnO/ITO window layer, Al contact.Then the thin film solar cells were assembled and the I-V tests were performed. We also explorate somedeposition conditions of CdS buffer layer, such as, pH, deposition temperature, deposition time, and getthe optimal conditions.