Application Of Protonated Carbon Nitride In Carbon-based Perovskite Solar Cells

With the development and utilization of fossil energy,problems such as energy depletion and environmental pollution have become increasingly severe,so the development and utilization of clean energy is particularly important.Solar energy has attracted widespread attention because of its wide range of applications,abundant resources,and clean and pollution-free advantages.The main application of solar energy is solar cells.So far,the development of solar cells has gone through three generations.Among them,Perovskite Solar Cells（PSCs）have the advantages of simple process and high photoelectric conversion efficiency.Traditional PSCs use Spiro-Me OTAD material as the hole transport layer and precious metal as the counter electrode,so the battery is expensive and has poor stability.Carbon materials and precious metals have a similar Fermi level,which can replace precious metals as counter electrodes,reducing battery costs and improving stability.However,the efficiency of carbon-based PSCs is relatively low.In order to improve the efficiency of the battery,this article starts from the modification of the perovskite layer and does the following three aspects of research:First,the perovskite film was modified with carbon nitride and protonated carbon nitride.Current density-voltage curve test（J-V test）found that adding 1.8 wt%of protonated carbon nitride,the photoelectric conversion efficiency of the battery can reach 6.61%.The protonation process introduces active groups-NH₂/-NH₃ on the surface of carbon nitride,and has a strong chemical interaction with the surface of the perovskite to passivate electron traps,improve the quality of perovskite crystals,and promote the extraction and transfer of electric charges.Secondly,adding protonated carbon nitride to the perovskite precursor solution has a poor dispersion effect,which is not conducive to the crystallization of the perovskite.Five solvents including?-butyrolactone（GBL）,dimethyl sulfoxide（DMSO）,N,N-dimethylformamide（DMF）,N,N-dimethylacetamide（DMAC）and isopropanol（IPA）are used to disperse the protonated carbon nitride,and then the dispersion is added to the perovskite precursor solution.The results show that when DMAC is used as the dispersant,the modification effect on the perovskite film is the best,and the obtained device has the highest efficiency,with the highest value being7.26%.Scanning electron microscope observations show that the perovskite crystals with protonated carbon nitride DMAC dispersion are better.Ultraviolet-visible absorption spectroscopy,steady-state fluorescence spectroscopy,time-resolved photoluminescence spectroscopy,and electrochemical impedance testing also show that perovskite added with protonated carbon nitride DMAC dispersion has better charge extraction and transport capabilities.Finally,in order to improve the stability of carbon-based PSCs,the FA-based perovskite was doped with a larger volume of PEAI at a low concentration to prepare a two-dimensional type PEA₂FA_n-1Pb_nI_3n+1 PSCs,which improves the efficiency while enhancing the stability.After the J-V test,it is found that the photoelectric conversion efficiency can reach up to 5.22%,and the stability is also significantly improved.