Application Of Electrospun Cu NWs Transparent Electrode In Perovskite Solar Cells

In recent years,with the increase of people’s demand for the development and utilization of new energy,perovskite solar cells,which as a new type of organic inorganic hybrid photovoltaic devices,have got the attention by many researchers for its low preparation cost,high power conversion efficiency,broad prospects for development and so on.The development of perovskite solar cells has been extremely rapid,its power conversion efficiency increases rapidly from 3.8%in 2009 to the nearest23.7%.Transparent electrode,with the high transmittance and good conductivity,is an important part of solar cells.At present,the ITO electrode,which is widely used in perovskite solar cells,has the characteristics of high preparation cost,scarce raw materials and poor bending of thin film,which limit its application in large area or flexible devices.Therefore,the selection and preparation of transparent electrode materials have become a hot research topic in the field of optoelectronics.Among them,copper nanowires have become the important alternative to replace ITO transparent electrodes because of their ultra-high aspect ratio,good light transmittance,considerable electrical conductivity,simple preparation method,low cost and bendable.Electrostatic spinning technology is the most common and easiest method to prepare nanowires.Therefore,in this paper,copper nanowires are prepared by electrospinning,and electrospun time is controlled to optimize the coverage of nanowires,and then the electrode performance is optimized.Finally,the copper nanowires transparent electrode with the best performance is obtained,the coverage is 22%,the transmittance is 81.6%,and the sheet resistance is 51.4Ω/口.And the copper nanowires have been successfully applied to perovskite solar cells,the specific content is divided into the following two parts:1.Using electrostatic spinning technology to prepare copper nanowires（Cu NWs）.By optimizing the parameters of concentration ratio of the electrospinning precursor,the applied voltage,the receiving distance,the flow rate and the humidity,the copper nitrate/PVP composite nanowires with uniform diameter and complete morphology were obtained,which are generally called the as-spun nanowires（as-spun NWs）.After high temperature air annealing,as-spun NWs are oxidized to copper oxide nanowires（CuO NWs）.After that,the CuO NWs was further reduced to copper nanowires（Cu NWs）by means of ethanol vapor phase reduction.In this process,by strictly controlling the reduction temperature and time,the Cu NWs web film with complete morphology,uniform diameter and smooth surface can be obtained.The diameter distribution,morphological characteristics and crystal structure of nanowires were characterized by optical microscope,scanning electron microscope and X-ray diffraction spectrum.2.The inverted perovskite solar cells of Cu NWs as bottom electrodes were prepared.The inverted perovskite solar cell structure of Cu NWs/PEDOT:PSS/CH₃NH₃PbI₃/PC₆₁BM/Bphen/Ag is designed.By controlling the electrospun time to change the coverage of nanowires,the effect of Cu NWs transparent electrode on the performance of the device under different coverage is studied.After optimizing the coverage of Cu NWs,it is found that when the nanowire coverage rate is 22%,the device based on the electrospinning copper nanowire electrode has the highest photoelectric conversion efficiency,and the efficiency value is5.32%.It can be shown that metal nanowires as transparent electrodes have certain application value in perovskite solar cells.It is further proved that Cu NWs can replace ITO transparent electrode and they have been applied in perovskite solar cells.