Exploring Research On The Effect Of Suppressing Defects In Perovskite Solar Cells

Organic-inorganic hybrid perovskite materials have received widespread attention and research worldwide due to their high light absorption coefficient,high carrier mobility and long diffusion length,and their adjustable band gap structure.In recent years,the development of perovskite solar cells has been rapid.In just 11 years,the photoelectric conversion efficiency of perovskite solar cells has climbed from 3.8%to 25.2%.Nevertheless,there are still many problems with this technology,such as defects in the device,including perovskite grain boundary defects,charge collection interface defects and newly added defects during the operation of the device,which are detrimental to the photoelectric conversion efficiency and stability of the device Impact,so how to suppress the adverse effects of defects has been an important research topic in this field.This paper systematically explores the method of reducing defects in the device manufacturing process and operation process.The main research contents are as follows:（1）Research on hole transport layer and interface defects.Three thin films of PEDOT:PSS,PEDOT:PSS/PTAA and PTAA:F₄-TCNQ were studied as hole transport layers to prepare perovskite solar cells.The energy level of the PEDOT:PSS and the perovskite active layer does not match,resulting in an open circuit voltage of less than 1 V and low photoelectric conversion efficiency.Then we studied the PEDOT:PSS/PTAA composite as a hole transport layer,which can increase the open circuit voltage of the device,and at the same time the photoelectric conversion efficiency of the device was increased from 15.69%to17.95%.PTAA has poor conductivity,so doping a certain amount of p-type dopant F₄-TCNQ improves the electrical conductivity of the film.The results show that PTAA is doped with 5wt%F₄-TCNQ,and the photoelectric conversion efficiency of the device is increased from14.16%to 17.28%.（2）Research on defects of perovskite active layer.Introducing D4TBP through the sec-butanol leaching process to directionally passivate the defects of the perovskite active layer.The results show that the performance of the device prepared by 0.25 mg/m L D4TBP sec-butanol is optimal.At the same time,compared with the reference device,the photoelectric conversion efficiency increased from 17.12%to 19.04%.Combining SEM,XRD and AFM characterization results proves that the introduction of D4TBP can effectively improve the surface morphology of the film and reduce the roughness.In addition,the steady state PL and electrical impedance chemical tests show that the introduction of D4TBP can effectively passivate the defects on the surface of the perovskite film.（3）Research on the defects of electron transport layer and interface.The non-fullerene material F8IC is doped in the electron transport layer PCBM.When 3 wt%F8IC is doped in PCBM,the photoelectric conversion efficiency of the device increases from 16.92%to18.42%.（4）Study on the spatial position of charged defects in the device by external electric field.The results show that the location of the charged defects in the device is affected by the size,time and direction of the applied electric field,light and dark state.When the device is not treated with an electric field,the photoelectric conversion efficiency of the device is 17.33%.When an external voltage of 0.9 V was applied to the device for 115 s,the photoelectric conversion efficiency of the device increased to 19.26%.At the same time,the open circuit voltage of the device rises from 1.13 V to 1.17 V.