| Since 2019,scientists have increased the efficiency of perovskite solar cells(PSCs)from the initial 3.9%to the current 25.7%by continuously improving the fabrication process and structure of perovskite solar cells.Currently,high-efficiency PSCs employ expensive hole transport layers(HTMs)and noble metal Au electrodes,and need to be fabricated in a glove box filled with inert gas,hindering the commercialization of PSCs.Therefore,in this paper,taking advantage of the unique advantages of perovskite materials that can simultaneously transport electrons and holes,in the air environment,mixed anion MAPb(I1-xClx)3 and MAPb(I1-xBrx)3 thin films were prepared as absorber layers,respectively.TiO2 is an electron transport layer and a hole transport layer-free carbon electrode PSCs to reduce cost and simplify the process.The structure,morphology,optical properties of mixed anion perovskite MAPb(I1-xClx)3 and MAPb(I1-xBrx)3 and their photovoltaic performance of perovskite cells are mainly studied.The specific research contents and findings are summarized as follows:1.When the perovskite film is prepared by the step-by-step liquid leaching method,the film formation of the PbI2 film plays a key role in the quality of the perovskite film.Therefore,this paper firstly studies the effect of precursor solution concentration on the morphology and crystallinity of PbI2 films.PbI2 powder was added to a mixed solvent composed of 800?L DMF and 200?L DMSO to prepare PbI2 precursor solutions with different concentrations.The FTO substrate was preheated on a constant temperature heating stage at 100°C for 10min,and the PbI2 precursor solution was spin-coated on it,and then annealed at 90°C.The results show that the concentration of the precursor solution has a great influence on the morphology and structure of the films.When the concentration of PbI2 precursor solution is 1M,the prepared PbI2 film is denser,and there are a few disordered distribution holes on the surface.The PbI2 films prepared at the concentration of the PbI2 precursor solution at 1.5 M are relatively loose,with many fine pores evenly distributed.2.The MAPb(I1-xClx)3 film and PSCs based on the MAPb(I1-xClx)3 film were prepared by a step-by-step liquid immersion method,and the crystal structure of the MAPb(I1-xClx)3 film with Cl-ion composition x was studied,morphological features and optical properties,and the photovoltaic performance of PSCs.The results show that the surface of MAPb(I1-xClx)3 is smooth and has a tetragonal crystal structure.With the increase of Cl-component x,the peak position of the diffraction peak shifts slightly to the direction of larger diffraction angle.Compared with MAPbI3,the absorption edge of MAPb(I1-xClx)3 is basically unchanged,indicating that its optical band gap does not change significantly,while the light absorption increases slightly in the wavelength range of 550-650 nm.Compared with PSCs based on MAPbI3 film,the photovoltaic performance of PSCs based on MAPb(I0.9Cl0.1)3 film is improved,and its photoelectric conversion efficiency is 8.68%.3.MAPb(I1-xBrx)3 films and PSCs based on MAPb(I1-xBrx)3 films were prepared by a step-by-step liquid immersion method,and the crystallinity of Br-ion component x on MAPb(I1-xBrx)3 films was investigated Influence of structure,topographical features and optical properties and photovoltaic performance of MAPb(I1-xBrx)3-based PSCs.The results show that with the increase of Br-component x,the flatness of the film surface becomes worse,and many large particles appear on the film surface.The replacement of I-ions by Br-ions in MAPb(I1-xBrx)3 leads to a decrease in lattice constant,and the XRD diffraction peaks of MAPb(I1-xBrx)3 films gradually shift to a larger diffraction angle.As the composition x increases from 0 to 0.5,the band gap of the MAPb(I1-xBrx)3 film increases from 1.59 eV to1.76 eV.The Br-component x also had a significant effect on the photovoltaic performance of PSCs,and PSCs based on MAPb(I0.9Br0.1)3 films exhibited the best photovoltaic performance with an efficiency of 11.70%.In addition,the cell still maintains 88.54%of the initial efficiency after being exposed to air for 850 h,showing good stability. |
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