Preparation And Properties Of Quantum Dot Sensitized ZnO Solar Cell Photoanode Materials

In recent years,quantum dot sensitized solar cells(QDSSC)have become a hot spot in the field of solar cells due to their low cost and high theoretical conversion efficiency.The performance of QDSSC photoanode material directly affects the performance of the solar cell.The preparation and properties of quantum dot-sensitized ZnO nanorod solar cells have been in-depth investigated in the thesis.ZnO nanorods and Y-doped ZnO(ZnO:Y)nanorods were prepared by two-step method on fluorine-doped tin dioxide(FTO)conductive glass Substrate.CuInS₂ quantum dots,CdS quantum dots and CdS/CuInS₂ co-sensitized quantum dots were prepared by continuous ion layer adsorption reaction method.A"sandwich"structure QDSSCs were assembled,whre ZnO and ZnO:Y nanorods sensitized with different quantum dots were respectively used as photoanodes,the electrolyte was polysulfide,and Cu_1.8S/Cu S was used as the counter electrode.The main research contents and experimental results are as follows:(1)Pure ZnO nanorods and Y-doped ZnO nanorods(ZnO:Y)were prepared by a two-step method.The effects of Y doping concentration,reaction temperature and reaction time on the phase structure,morphology and optiacl performance of ZnO:Y nanorods were studied.The experimental results show that the synthesized pure ZnO nanorods and ZnO:Y nanorods grow along the c-axis preferential orientation,which is hexagonal wurtzite structure.When the Y-doping concentration is 0.05 M,the reaction time is 5 h,and the reaction temperature is 95?,the(002)diffraction peak of the Y-doped ZnO sample is the strongest;the sample exhibits a columnar structure with a hole on the side The nanorods have a diameter of 450 nm and a length of 2.4?m;The sample has an UV luminescence peak with a lower intensity at 390 nm and a Visible light luminescence peak with a higher intensity at 600 nm.Compared with pure ZnO nanorods,ZnO:Y nanorods have a red shift;the band gap optical band gap of the sample is 3.23 e V.(2)CuInS₂ quantum dots,CdS quantum dots and CdS/CuInS₂ co-sensitized quantum dots were prepared by continuous ion layer adsorption reaction method(SILAR).The effect of deposition times on the phase structure,morphology and absorption spectrum of CdS,CuInS₂ quantum dots and the assembled quantum dot sensitized ZnO solar cells were studied.The experimental results show that the adsorption capacity of CuInS₂ quantum dots and CdS quantum dots gradually increases with the increase of the number of depositions.When CuInS₂ is deposited 5 times,the prepared CuInS₂ quantum dots have a chalcopyrite structure and the strongest light absorption.The efficiency of the sensitized ZnO solar cell is 1.23%;when CdS is deposited 7 times,the light absorption is the strongest.The efficiency of the sensitized ZnO solar cell reached 0.85%;photoelectric conversion efficiency of the solar cell using CuInS₂ deposited five times and CdS deposited seven times co-sensitized ZnO reached a maximum of 1.23%.(3)CuInS₂ quantum dot-sensitized ZnO and ZnO:Y nanorod photoanode were prepared by continuous ion layer adsorption(SILAR),polysulfur electrolyte,and Cu_1.8S/Cu S as the counter electrode.The light absorption performance of different photoanodes and the photovoltaic performance of solar cells were studied.The experimental results show that the ZnO:Y/CuInS₂ photoanode material has the strongest UV-Visible light absorption,and the parameters of the assembled solar cell with this anode material are higher than the CuInS₂ quantum dot sensitized pure ZnO nanorod solar cell.The solar cell assembled with CuInS₂ quantum dots sensitized Y:ZnO nanorods had a short-circuit current density of 4.9 m A/cm²,an open-circuit voltage of 0.46 V,a fill factor of 0.31,and a photoelectric conversion efficiency of1.85%.