| In recent years,quantum dots have attracted extensive attention due to their unique physical and chemical properties.The conventional preparation methods of quantum dots are limited due to the complicated preparation process and complex product composition.As a new preparation method of micro-nano material,pulsed laser irradiation in liquid(PLIL)has unique advantages of selective heating,simple preparation,and the morphology and size of the obtained products are controllable,which has great application potential in the preparation of quantum dots.In addition,the modification of quantum dots can passivate the perovskite light-absorbing layer,which is expected to optimize the photoelectric performance of perovskite solar cells(PSCs)and further improve their power conversion efficiency(PCE)and stability.Thus,in this thesis,a series of quantum dots were prepared by the PLIL technology and were applied to improve the photoelectric performance of PSCs.The main research contents and conclusions of this thesis are as follows:(1)The preparation methods of different types of quantum dots were studied.A series of quantum dots were successfully prepared by laser irradiation,including carbon quantum dots based on chlorobenzene and ethyl acetate,tungsten sulfide quantum dots and core-shell gallium indium quantum dots.The results indicated that the carbon quantum dots prepared by laser irradiation have obvious fluorescence properties,and the morphology and size of carbon quantum dots can be adjusted by changing the laser fluence.With the increase of laser fluence,the tungsten sulfide nanomaterials first become nanospheres and then form quantum dots,and the particle size increases first and then decreases.The gallium indium liquid metal was turned into gallium indium quantum dots with core-shell structure by laser irradiation,and the particle size increases first and then decreases with the increase of laser fluence.(2)The carbon quantum dots,tungsten sulfide quantum dots and core-shell gallium indium quantum dots prepared by laser irradiation were applied to the perovskite lightabsorbing layer by one-step anti-solvent method.The study showed that carbon quantum dots and tungsten sulfide quantum dots can reduce the defects in the perovskite lightabsorbing layer by passivation of their surface groups.As an electron storage center,coreshell gallium indium quantum dots can promote the temporary storage and migration of electrons.Therefore,the optimization of quantum dots can effectively decrease the surface roughness of the perovskite light-absorbing layer,increase the lifetime of carriers,promote the carrier transport,and thus improve the photoelectric performance of perovskite lightabsorbing layer.(3)The effects of the above quantum dots optimization on the photoelectric performance of PSCs were further studied.The results showed that photoelectric performance of PSCs was enhanced by the optimization of quantum dots.The maximum PCE of PSCs optimized with carbon quantum dots(chlorobenzene,ethyl acetate),tungsten sulfide quantum dots and core-shell gallium indium quantum dots were 14.95%,16.43%,16.85% and 15.55%,respectively,which was greatly improved when compared with the PCE of 13.11%(chlorobenzene)and 13.27%(ethyl acetate)of unoptimized PSCs.(4)The photoelectric performance improvement of PSCs optimized by quantum dots was theoretically analyzed,and the influence mechanism of carbon quantum dots,tungsten sulfide quantum dots and core-shell gallium indium quantum dots on the open circuit voltage,short current density and filling factor of PSCs was deeply studied.Through further analysis of the performance differences of PSCs optimized by quantum dots in this thesis,the study showed that the tungsten sulfide quantum dots can not only passivate the defects in the perovskite light-absorbing layer but also make the energy levels between functional layers of PSCs more matching,thus greatly promoting the transport of carriers,and eventually improving the photoelectric performance effectively. |
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