Study On The Passivation Ofperovskite Solar Cells Using Silicon Oxide

Energy is the driving force for the development of human society.With the depletion of non renewable energy and the aggravation of environmental pollution,people gradually turn their attention to green and clean renewable energy.Therefore,the research and utilization of solar energy has become the focus of everyone's attention.Among them,the preparation and application of solar cells are currently the main effective way to utilize solar energy.Organic-inorganic perovskite materials have become the main research materials in many fields such as solar cells,photodetectors,and light-emitting diodes due to their excellent optical properties.In the past ten years,the efficiency of perovskite solar cells has risen rapidly to 25.2%today.However,there are still some difficulties in the research of perovskite solar cells,which affect the further improvement of device efficiency and stability.For example,the existence of defects in perovskite films,interface carrier recombination,and so on will seriously reduce the service life of the devices,thus limiting the development of perovskite solar cells.In this paper,aiming at the existing problems of perovskite solar cells,the passivation mechanism of Si O₂oligomers formed by adding tetraethyl orthosilicate?TEOS?to the perovskite precursor to the perovskite film and the effect of different dopant concentration on the properties of perovskite films and devices were studied.In order to reduce the interface recombination,an insulating layer was evaporated between the electron transport layer and the perovskite layer by electron beam technology,and the influence of the insertion of the insulating layer on the device performance was studied.The results are as follows:?1?By doping a certain amount of TEOS in the perovskite precursor,with the hydrolysis and condensation reaction of TEOS,silica oligomer clusters will be formed on the perovskite grain boundary and surface.As an effective defect passivator,it can passivate the perovskite film in situ and reduce the charge carrier recombination.The passivation mechanism of silica oligomer was revealed by DFT calculation.It was found that the perovskite film doped with TEOS exhibited larger perovskite grain size,longer carrier lifetime,stronger charge carrier dynamics and lower trap density.After the perovskite solar cell was optimized based on TEOS doping,the PCE of 19.64%was obtained.In addition,since the silicon dioxide passivates the grain boundary to form an in-situ protective layer or blocking layer to prevent water from infiltrating through the perovskite grain boundary,the passivated device has high humidity and thermal stability.After being placed in a certain humidity atmospheric environment for 1000 hours,it maintains nearly 90%of its initial performance.while after thermal accelerated aging at 120?for 2 hours,it still maintains 87%of its initial performance.?2?Based on the principle of insulation tunneling,an ultra-thin Si O₂insulating layer was deposited by electron beam between the SnO₂electron transport layer and the perovskite layer,and the effect of different thickness of interface layer on device performance was studied.The introduction of a certain thickness of Si O₂insulating layer can promote electron transport and block hole entry.A series of characterization methods proved that after the introduction of the 0.3 nm insulation layer,the perovskite film was flatter,the grain gets a certain degree of growth,the defect of perovskite film was reduced,and the separation of electrons and holes was promoted,so as to reduce their recombination at the interface and improve the comprehensive performance of perovskite solar cells.Compared with the pristine device,the device with the Si O₂insulation layer increased from 17.52%to 19.58%.In addition,the devices after inserting the insulation layer ware placed in a certain humidity atmospheric environment for 1000 hours,its initial performance was maintained at nearly 91%.The pristine device was only maintained 62%of its initial performance.