Study On Preparation And Properties Of AZO/Lead Selenide Quantum Dots Solar Cells Materials

Known as third-generation solar cell,quantum dot solar cells are receiving more and more attention because of the advantages of adjustable band gap,solution processing and large-area film fabrication.As a kind of direct narrow-bandgap semiconductor material,lead selenide quantum dots have good light absorption ability in the infrared band and can generate multi-exciton effect,so they are used as a material with great potential in photovoltaic devices.However,despite the rapid increase in efficiency of quantum dot solar cells,difficulties such as insufficient air stability and low overall efficiency are still exist.At the beginning of this dissertation,the research work on the optimization of quantum dot solar cells can be mainly divided into two directions: quantum dots surface ligand exchange engineering and structure optimation of quantum dots solar cells.This topic research combines the characteristics of two directions.On the one hand,the improved synthesis method is used to prepare lead selenide quantum dots,which effectively passivate the surface of quantum dots.On the other hand,to enhance the seperation of carriers,the bulk heterojunction cells are prepared by using the electron transport layer of microscopic three-dimensional structure.On the basis of the latest synthesis method of quantum dots,the synthesis process was further explored and optimized.The CdSe quantum dots with the best size distribution and high optical absorption were prepared.Then the CdSe quantum dots were used as precursors to synthesize the lead selenide quantum dots for solar cells by cation exchange method.Using spin-coating method,lead selenide quantum dot films were prepared,and were treated with ethylenedithiol solution in acetonitrile for ligand exchange.Though results showed that morphology of quantum dot films were etched by ethylenedithiol solution,the optical absorption coefficient of quantum dot films was greatly improved.Using zinc oxide dissolved in ammonia aqueous solution as zinc source,oriented zinc oxide nanowire arrays with high crystallinity were successfully grown on ITO glass by hydrothermal growth method.Zinc(AZO)nanowire arrays were fabricated and the effects of Al doping concentration on the morphology and photoelectric properties of nanowire arrays were investigated.Heterojunction lead selenide quantum dot solar cells with and without AZO nanowire arrays as electron transport layers were fabricated.Compared with the two kinds of solar cells,the results showed that the heterojunction solar cells with micro-three-dimensional AZO nanowire arrays as the electron transport layer have higher short-circuit current density,and performance of solar cells were improved.