Investigation On The Electric Field And Passivation Control Of Chlorine-iodine Based Perovskite Solar Cells

In recent years,with the improvement of the economic level,energy consumption has become a more and more serious problem for people.The utilization and development of the renewable energy has become the attention of the governments from all over the world.As one of the clean energy,solar energy is favored by scientists in various countries for its advantages of low consumption and no pollution.Making full use of solar energy as is much as possible is significance to reduce environmental pollution and improve citizens' sense of happiness in life.Although the inorganic silicon solar cell has been widely applied in the market,the high production cost and the inefficient power conversion efficiency(PCE)become the important factors to limit its further development.Recently,a kind of new organic-inorganic hybrid perovskite solar cells(PSCs),due to their simple manufacturing technology,flexible preparation and low cost,is selected as one of the ten major technological advances in 2013.The works are mainly focus on the perovskite absorber layer of PSCs.Through the different chemical materials and physical treatment to study the influence on the film morphology,crystal arrangement,dielectric properties,and photoelectric properties of the device.Firstly,based on the perovskite film doped with P type organic semiconductor polymer [N-9 00-hepta-decanyl-2,7-carbazole-alt-5,5-(4 0,7 0-di-2-thienyl-2 0,1 0,3 0-benzothiadiaz-ole)](PCDTBT)as the optical absorber layer,the photoelectric properties of the films and devices with and without dopant are discussed.The results show that PCDTBT can make some interaction with perovskite crystals,significantly improving the grain size of the films,and effectively promoting the transport and collection of carriers.Through the regulation of the doping concentration,it is found that when the doped PCDTBT is excessive,the pinholes will increase although the perovskite grain still becomes larger,which is not conducive to the improvement of device performance.The optimum doping concentration is 0.3 mg/mL,when the PCE of the device can reach 15.76%,increased 16% compared to the reference device.Take the 0.3 mg/mL as the object,the optimized mechanism is explained by a series of contrasts,characterization and analysis of the photoelectric properties of the perovskite films and devices.The effect of a vertical external electric field(EEF),applied during the annealing process of optical absorption layer,on crystal alignment,ion transport and dielectric properties is also researched by this thesis.By comparing the value and direction of the applied EEF,the photoelectric properties of the regular and inverted perovskite solar cells are analyzed.The experimental results show that the growth of perovskite crystals can be assisted along the vertical EEF,particularly,the direction of the applied EEF consistent with the built-in electric field can effectively promote exciton dissociation,transport and collection.By optimizing the EEF,the open circuit voltage,short circuit current density and fill factor of the device can be significantly improved,and the PCE can reach 19.18% in the regular device.At the same time,the unusual hysteresis phenomenon of perovskite solar cells is further studied through the characterization of ion migration and dielectric properties,since the inevitable ionic migration will happen under the EEF.The research is based on the chemical structure of the perovskite crystals and the photovoltaic principle of the solar cells to study the influence of the different manufacturing processes on the crystallization of perovskite absorber layer,and improve the photoelectric efficiency of the device through the optimization of the component and manufacturing method.The function mechanisms are explained by the systematic characterization and analysis of the optical,electrical and chemical properties of perovskite films and devices.The researchers hope that the explanations and findings in this thesis can be a reference for other researchers to solve some key problems for the commercialized application of the PSCs.