The Modification Of PEDOT:PSS Hole Transporting Layer Of Perovskite Solar Cells And Its Photoelectric Performance

The depletion of fossil energy is inevitable as fossil energy is consumed.Developing solar cell technology becomes a key part of clean energy utilization for the inexhaustible solar energy.As the energy conversion efficiency raises from the initial energy conversion efficiency of 3.8%to 23.3%in a few years,perovskite solar cells become the most prominent concept solar cells.The perovskite solar cells have excellent photoelectric properties and the potential of commercialization based on a solution and a spin-coating process technology However,there is still a long way to go before realizing commercialization.First of all,the TiO₂ substrate of traditional structure of the perovskite solar cell needs a high temperature to sinter,which not only needs high energy dissipation but not conducive to the preparation of flexible devices.There is also obvious hysteresis in the devices with TiO₂ as the electron transport material.Therefore,the inverted perovskite p-i-n solar cell based on PEDOT:PSS as the hole transport material has been widely concerned due to its low delay,low temperature preparation,and suitable for the preparation of flexible devices.But in achieving high efficiency and good stability,the inverted perovskite p-i-n solar cells are still facing some problems.The perovskite thin film deposition on PEDOT:PSS exists pinholes and incomplete covering resulting in a decline of device performance.In addition,the work function of PEDOT:PSS is between 4.9 to 5.1 eV,which caused the incomplete ohmic contact between the perovskite light absorption layer?5.4 eV?and the hole transport layer,resulting in loss of the open circuit voltage.On the other hand,PEDOT:PSS is easy to absorb water,which will accelerate the decomposition of perovskite material.In this paper,we modify the hole transporting materials by?1?changing the polarity of PEDOT:PSS precursor solution by DMF.The sulfonic acid distribution was homogenized in the normal direction.The work function of the PEDOT:PSS layers increased from 4.71 eV to5.07 eV,and the conductivity of PEDOT:PSS increased from 3×10^-4 S/cm to 0.45 S/cm.The as-deposited perovskite films were more uniform with larger grain sizes and less pinholes,resulting in an improved V_OC from 0.93 V to 1.048 V,while the efficiency was increased from11.5%to 16.8%.Solar cells without encapsulation under the 50 hours and 50%humidity aging test showed 7%degradation of fill factor?FF?with 50 v/v%PEDOT:PSS layer,while the fill factor decreased 11.2%in the 0 v/v%PEDOT:PSS layer,respectively.?2?Adding functional small molecules alanine to PEDOT:PSS to make structure reconstruction of PEDOT:PSS.After alanine modification,the electrical properties and water absorption characteristics of PEDPT:PSS were improved.It effectively inhibited the production of yellow phase of perovskite deposited on PEDOT:PSS.The crystallinity,transmission and collection capacity of the charge of perovskite film were improved.Highly efficiency and stable solar cells are obtained.