Study On Photoelectric Performance Of ZnO Quantum Dot Sensitized Solar Cells Based On Electrodeposition Method

In the third generation of solar cells,the industrial application of dye-sensitized solar cells is limited by its own defects.However,with the rapid development of quantum dot nanomaterials,quantum dot sensitized solar cells(QDSCs) with more competitive advantages have attracted much attention.The photoanode is the core of QDSCs,and its material selection must have good charge transport performance to ensure the effective photocurrent output.At present,ZnO nanomaterials have high electron mobility,variable and controllable nanometer morphology,which is considered as a transport layer replacement material with greater advantages than traditional TiO₂ photoanode.Among these two advantages,the morphological diversity of ZnO material are easy to satisfy the large specific surface area required by the quantum dot sensitizer,and more quantum dots can be adsorbed on its surface,so the photoelectric conversion efficiency of the cells have a greater room for improvement.The research of this paper is mainly focused on the preparation of high-efficiency solar cells by combining electrodeposition of ZnO films with quantum dot sensitization technology,so as to give full play to the characteristics of high efficiency,low cost and easy operation of electrodeposition technology.It provided a highly industrialized method for the preparation of quantum dot sensitized solar cells.In this paper,the deposition parameters of ZnO films prepared by potentiostatic deposition were first screened.The effects of deposition potential,deposition temperature,and concentration of the deposition solution on the morphology and structure of the thin film were studied on the basis of Zn(NO₃)₂ and hexamethylenetetramine as the deposition solution.Then ZnO films were sensitized with Cd S,the energy conversion efficiency of the assembled QDSCs was tested,and the optimal deposition parameters were finally determined.The morphology of ZnO films obtained under different conditions and the J-V characteristics of the corresponding QDSCs were characterized by scanning electron microscopy(SEM) and electrochemical voltammetry curve test.The results showed that the morphology of the obtained ZnO film was mainly nanorods.The coverage,crystallinity and diameter of ZnO are controlled by the deposition voltage,temperature and concentration,respectively.The optimal parameters of electrodeposition after screening ware:-1.1 V,70? and 0.025 mol/L.Under this condition,the energy conversion efficiency of ZnO-Cd S QDSC was 0.069%.Then,the sensitization of different quantum dots on ZnO films obtained under the best electrodeposition conditions was studied,and the light absorption characteristics and energy conversion efficiency of assembled QDSCs were tested.The changing rules of different Cd S sensitized layers and Cd Se deposition time affecting the cells performance was analyzed.The results showed that,comparing with only Cd S sensitization,after the introduction of Cd Se,the co-sensitization of double quantum dots extended the absorption wavelength of the photoanode in the visible region from 400 nm to 600 nm.And,the short-circuit current density and fill factor of the Cd S/Cd Se co-sensitized photoanode were significantly improved compared to only Cd S quantum dot sensitization.In addition,three electrodeposition additives were selected to modify the morphology and structure of ZnO,namely PVA,NH₄Cl and KCl.After preliminary screening,it was found that KCl had the best modification effect.The effect of its concentration on the structural transformation of ZnO was studied in depth using KCl as a structural modifier.And the ZnO thin films obtained at different concentrations were used as photoanodes in QDSCs prepared by encapsulation,conducting electrochemical performance tests.The results showed that when the KCl concentration was 0.075 mol/L,the QDSC with the ZnO film as the photoanode had the best performance and the highest short-circuit current density and energy conversion efficiency,which were 3.17 m A/cm² and 0.356%,respectively.It was2.41 m A/cm² and 0.271% higher than those without KCl addition.