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

Perovskite solar cells,a new type of solar cells based on organo-metal halides,have made significant progress in recent years.Currently,researchers around the world are conducting research on commercialization,but the balance between stability and efficiency has always been a challenge.A major cause of degradation of perovskite solar cells is the decomposition of perovskite crystals reaction with water and oxygen in the atmosphere such as CH₃NH₃PBI₃(MAPBI₃).In addition,due to ion diffusion,metal electrode silver(Ag)reacts with iodide(I^-)and degrades.The hotspots of perovskite solar cells is how to maintain the long-term stability of perovskite solar cells while ensuring efficiency.Among them,carbon electrode based perovskite solar cells is a kind of low-cost and highly potential stable perovskite solar cells.However,although carbon electrode based perovskite solar cells has improved the stability of the device,there is a big gap in photoelectric conversion efficiency compared with conventional perovskite solar cells.Generally,the poor performance of carbon electrode perovskite solar cells is mainly related to the following factors:(1)inadequate hole extraction performance of carbon materials,(2)carbon electrode has poor contact with the perovskite layer,(3)energy level matching between carbon electrode and perovskite film is not balanced which is the main reason that the carbon based perovskite solar cells is not satisfactory.For the realization of efficient and stable carbon electrode based perovskite solar cells,we mainly did the following work:Recrystallized MAPbI₃ perovskite thin film for carbon electrode solar cell:The poor contact between the carbon electrode and the perovskite layer made reduce of perovskite solar cells performance.We optimized the interface to improve the performance of the device.Firstly,the MAPbI₃film remaining in PbI₂was prepared by one-step deposition method,and then the MAPbI₃film was annealed after MAI treatment.After adjusting the MAI concentration systematically,the residue PbI₂on the upper surface was removed successfully,and the particle size of MAPbI₃ was increased obviously,the recombination of electrons was reduced.The photovoltaic efficiency(PCE)of carbon based perovskite solar cells was increased from 10.63%to 12.21%.Low-pressure treatment of Cu SCN hole transport layers for enhanced carbon based perovskite solar cells:The poor performance of carbon based perovskite solar cells is also related to the poor performance of the hole extraction of carbon materials.We introduced Cu SCN as the hole transport layer and protected the perovskite film through low pressure treatment(LPT).Because of the solvent DES will destroy the perovskite film by heating or standing at room temperature.Therefore,only LPT treated CUSCN can increase the PCE of perovskite solar cellsfrom 10.6% to 13.05%.More importantly,the hysteresis of the device is significantly reduced due to the improvement of level alignment and hole extraction between perovskite and carbon electrode.Meanwhile,the hydrophobicity of Cu CN HTL can significantly improve the stability of perovskite solar cells.Double perovskite film CS₂AgBiBr₆for carbon based perovskite solar cells:The main reason of instability with conventional perovskite solar cells is lead-based perovskite will react with water and oxygen after the atmosphere.Herein,we use double perovskite Cs₂AgBiBr₆alternative lead-based perovskite,which were used as the light-absorbing layer of carbon based perovskite solar cells,the thin films had smooth morphology and uniform grain size.The device prepared by this method has high repeatability,and the best PCE of carbon electrode perovskite solar cells is 1.47%.