Enhancing The Performance And Of Carbon-based Perovskite Solar Cells By Cold Isostatic Pressing Method

Recently,the third-generation photovoltaic technology,represented by perovskite solar cells,has demonstrated its enormous application prospects.In just a few years,the efficiency of organic/inorganic hybrid perovskite solar cells has reached 22.7%.However,most of the perovskite solar cells(PSCs)still use the method of vaporizing precious metal to prepare the counter electrode.The use of vacuum equipment and precious metal has greatly limited the cost of such solar cells.In this regard,the use of inexpensive carbon material as the counter electrode of new perovskite solar cells can avoid the use of precious metal.At the same time,it achieves full printing of perovskite solar cells,effectively avoiding high cost issues.At present,the main problem of PSCs based on carbon electrode is their low photoelectric conversion efficiency.The main reasons are as follows:1.The carbon electrode perovskite solar cell adopts porous membrane structure,and the density of the perovskite light-absorbing material filled in the membrane is not high enough,which affects the electron transport and exchange;2.The carbon electrode is not as conductive as metal electrode.It has a high internal resistance.Secondly,in order to make the device structure denser,aims at the porous structure of carbon based PSCs,we adopts the cold isostatic pressing(CIP)method to make the device structure more compact.The results show that after 225 MPa cold isostatic pressure,the water contact angle on the porous carbon electrode surface is increased from 60 ~o to 105 ~o,indicating that the structure is more compact.At the same time,the fill factor of the device was increased from 0.536 to 0.661,and the efficiency was improved from 9.1%to 11.6%.The unpackaged device,after being stored for a long period of 1500 h at room temperature and relative humidity of 50%,can maintain more than 90%of the photoelectric conversion efficiency,reflecting a good humidity stability.On this basis,we have prepared large-area perovskite solar cell modules based on carbon electrodes,achieving a device efficiency of 4.46%at a size of 7 cm×16 cm.In order to improve the efficiency of the solar cell module,we finally explored the feasibility of using a nickel electrode to replace the carbon electrode material.The mesoporous nickel electrode was prepared by hydrogen reduction of nickel oxide.The nickel electrode-based PSCs have a significant increase in fill factor,indicating that the internal resistance of the device is significantly reduced.Although efficiency is currently low,we believe that nickel electrodes still have great potential for application in large-area solar cell modules.