Research On Efficiency And Stability Of Perovskite Solar Cells Based On Carbon Electrode

In recent years,organic-inorganic hybrid perovskite materials have attracted extensive attention due to their high absorption coefficients,low excitation binding energies,long carrier diffusion lengths,and low defect state densities.After over ten years of development,the photoelectric conversion efficiency（PCE）of perovskite solar cells（PSCs）has rapidly increased from 3.8%to even superior 25%,reaching the same level as that of commercial polycrystalline silicon cells.However,the perovskite absorber layer is easily decomposed under environmental factors such as moisture,temperature,oxygen,and ultraviolet light,resulting in a decrease in the long-term stability of PSCs,which severely restricts the commercial application.Therefore,it is urgent to improve the stability of the perovskite absorber layer,constructing the stability of PSCs devices.Various research strategies have been employed to effectively reduce the internal and surface defects of perovskite films.The solutions to the issue of poor stability include additive engineering,component engineering,anti-solvent engineering,and interface engineering,which can reduce the defect-state density of perovskites and enable the attainment of high-quality perovskite films.Additive engineering is the most commonly used method to improve the quality of perovskite films,reduce defects,and enhance the performance of PSCs.In this paper,two main works have been carried out to improve the stability and efficiency of perovskite solar cells.（1）Defect passivation is a crucial process for achieving high-performance perovskite solar cells.Herein,we demonstrated the synergistic effect of anti-solvent and component engineering for effective passivation to attain highly stable perovskite solar cells,specifically,for ethyl acetate as the anti-solvent and Cs Br as the additive in the MAPb I₃ precursor solution.It is found that the rapid solvent evaporation results in fast nucleation and the Cs Br assists the perovskite grain growth.The synergistic effect of anti-solvent and additive engineering leads to increased perovskite grain size,reduced defect density,improved quality of the perovskite thin film,and,finally,enhanced efficiency and stability of the ITO/Sn O₂/perovskite/carbon device.The influence of this synergistic effect on the morphology and photovoltaic performance was systematically investigated.We designed and constructed printable PSCs with hole-transport-layer-free carbon electrodes,which achieve a champion PCE of 16.45%,FF of 72.63%,J_SC of 19.90 m A/cm~2,and V_OC of 1.14 V.In this work,we demonstrate a facile and low-cost approach to obtain highly-stable C-PSCs and provide a promising strategy for future commercial application.（2）The stability of perovskite solar cells is one of the main factors restricting their commercialization.Here,we used Zn O nanoparticles as the UV absorber for the electronic layer and 2-hydroxybenzophenone（HBP）as the UV absorber for the perovskite layer,which synergistically improves the stability of the perovskite cell.Zn O nanoparticles are beneficial to improving electron transport efficiency,and can also effectively hinder part of the damage from UV light to perovskite films.HBP can passivate the defects and absorb part of the ultraviolet light to improve the quality and stability of the film,respectively.The ITO/Sn O₂/Zn O/MAPb I₃-HBP/Carbon PSCs exhibited a PCE of 16.39%,J_SC of 23.26 m A/cm~2,V_OC of 1.12 V,and FF of 62.96%.The photostability and long-term stability were significantly improved compared to the control device.The unencapsulated devices retained 94%of the initial efficiency after792 hours of storage at ambient conditions（RH=30%）,significantly improving the wet stability of the devices.This provides an important strategy for improving the stability of printable perovskite cells.In summary,this work provides theoretical guidance and an experimental basis for the selection of additives in perovskite solar cells and the improvement of the conversion efficiency and stability of the perovskite solar cells.