Study On Improving Efficiency And Stability Of Invertered Methylamine Lead Iodide Perovskite Solar Cells By PMMA

Perovskite solar cells have received a lot of attention since their introduction,and their maximum efficiency has reached 24.2%,which is closer and closer to the theoretical limit of perovskite batteries.But there are also some difficulties in the current research.On the one hand,the electron-hole pair recombination caused by defects in the optical absorption layer and the electronic transmission layer of the device reduces the carrier life and limits the further improvement of the device performance.On the other hand,perovskite batteries have poor stability.Perovskite is easy to decompose under certain conditions of water,oxygen and light,which seriously affects the battery life.In this paper,by introducing the passivator PMMA,on the one hand,the microscopic morphology of perovskite thin film was improved to obtain a smoother and better quality light absorption layer and electron transmission layer,so that the device efficiency was significantly improved.On the one hand,it can isolate water and oxygen better and effectively improve the stability of the device.The main works of this paper are showed as follows:1.We prepared structure of ITO/PEDOT:PSS/MAPbI₃/PCBM/BCP/Ag as standard device,PMMA is added in the precursor solution,optimize the PMMA doped concentration of 1 mg/ml,calcium passivator titanium seam annealing temperature using condition of 120℃is the best.The performance parameters of devices containing PMMA,including Jsc,Voc,FF and PCE,were higher than those of standard devices.The photoelectric conversion efficiency of standard devices is 11.11%,and the optimized device efficiency is 13.01%,an increase of 1.9%.After the introduction of passivator,the stability of the battery is also greatly improved（stored at 25℃and with relative humidity of 60%-70%air）,the efficiency of standard devices decays to almost zero on day 8,whereas devices containing PMMA maintain 70%of their initial efficiency on day 8.Through the analysis of the film characterization results,it can be concluded that the introduction of PMMA into the perovskite presomal solution can increase the grain size of perovskite,reduce the surface roughness,effectively reduce the non-radiative composite,increase the carrier life,and thus improve the photoelectric conversion performance and stability of the device.2.We prepared structure of ITO/PEDOT:PSS/MAPbI₃/PCBM/BCP/Ag as standard device.On the one hand,we added the PMMA in the PCBM solution,explore the best doping concentration of 2 mg/ml,efficiency of the optimized device was 13.78%,2.67%higher than that of the standard device..On the other hand,we introduced PMMA into both perovskite and PCBM,and obtained the optimal doping concentration of 1mg/ml.The photoelectric conversion efficiency of the optimized device was 11.87%,0.76%higher than that of the standard device.The stability of the two devices also increased to different degrees.The device was stored in the air for 8days,and the photoelectric conversion efficiency of the standard device almost attenuated to zero.The device with passivator in the PCBM layer still maintained57%of the initial efficiency,while the device with passivator in the perovskite layer and PCBM layer was 78%of the initial efficiency.Preparation of thin films were characterized by different conditions,it can be seen that adding PMMA in the electron transport layer,can make PCBM surface more smooth,make there is a better contact between the light absorption layer,the electron transport layer and metal electrode,reduce the recombination of electronic-hole pair at the interface and defects,have important influence on the performance and stability of the device.In conclusion,PMMA can improve the efficiency and stability of invertered methylamine lead iodide perovskite solar cells.According to the different doping methods,the effect is from high to low:PMMA is added to both the light absorption layer and the electronic absorption layer,PMMA is only introduced into the light absorption layer,and PMMA is only introduced into the electronic transmission layer.