Structure Optimization And Stability Of Cs_xFA_1-xPbI_1.80Br_1.20 Perovskite Solar Cells

As heavy industry increasingly developed,renewable energy sources(coal,oil)are running out,energy issues have become increasingly tricky,so the solar energy as a green renewable energy is prepared into the solar cell device of sustainability development gradually got the attention of the researchers.Solar cells are a very promising method to offset the carbon emissions of equipment,and it also provides an alternative way to meet the growing demand for energy consumption.Organic-inorganic(FA-Cs)halogenated perovskite solar cells have been considered as a promising perovskite material because of their simple preparation process,higher photoelectric conversion characteristics and excellent device stability,and naturally become the focus of research.In recent years,studies on inorganic-organic hybrid PSCs have been widely reported,especially on FA⁺/Cs⁺PSCs.However,few studies have analyzed and explained the mechanism of lattice structure change of Cs_xFA_1-xPbI_1.80Br_1.20 PSCs from the perspective of chemical bond structure,and few studies have focused on the stability of PSCs with the same perovskite materials and different device structures.Therefore,in this study,we further studied the problems mentioned above that have not been fully solved.On the one hand,for Cs_xFA_1-xPbI_1.80Br_1.20 absorbent layer material,the best ratio of FA⁺/Cs⁺was firstly determined.A series of stability studies were carried out for PSCs formed by this ratio.On the other hand,the light-absorbing layer material with excellent device performance in the above study was applied to the perovskite device structure of the hole-free transport layer of carbon electrode.On this basis,the efficiency and stability of carbon electrode device were further improved by adding a new electron transport layer.Specific research contents are as follows:(1)Study on the performance and stability of gold electrode perovskite solar cells prepared by using Cs_xFA_1-xPbI_1.80Br_1.20 as absorbent layer material and replacing FA⁺with different proportion of Cs⁺.A variety of perovskite adsorbents were prepared by rotary coating method,in which different proportions of Cs⁺were partially replaced by FA⁺.At the same time,the stability also achieved a remarkable promotion,which was demonstrated by X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD)and Nuclear Magnetic Resonance(NMR),maintained 90%of the initial PCE in air(25?,55-60%humidity)for 4 days,and 50%of the initial PCE when heated in a 200? hotplate for 2 hours,the PSCs with Cs_0.15FA_0.85PbI_1.80Br_1.20 as the perovskite absorbing layer material were determined,achieving high efficiency PSCs with a stable PCE of16.2%.These analyses indicate that 15%Cs⁺can induce the lattice shrinking,reduce the specific traps and inhibit the phase transition,thus improving struture stabilities of Cs_0.15FA_0.85PbI_1.80Br_1.20 PSCs under atmosphere and calefaction.These results provide an effective way for fabricating stable and efficient inorganic-organic perovskites solar cells with promising properties.(2)Fe-TiO₂ nanometer sheet preparation and its load in the carbon-Cs_0.15FA_0.85PbI_1.80Br_1.20 perovskite solar battery performance and stability of the research.The Cs_0.15FA_0.85PbI_1.80Br_1.20 material was applied to carbon electrode PSCs devices,we have prepared a new device structure without the hole-transporting materials,and on this basis,Fe-TiO₂ nanosheets were prepared and deposited on the mesoporous TiO₂ layer.It can be concluded that after adding Fe-TiO₂ layer,the electron transport rate is improved,and the device efficiency is increased from 9.93%to 11.57%.After the complete device is placed in the air(without packaging)for 24 days,the stability of the device containing Fe-TiO₂ layer was also improved.