Inkjet Printed Silver Nanowire Networks As Electrode For Perovskite Solar Cells

Transparent conductive electrodes are widely used in photovoltaic devices,touch screens,liquid crystal displays(LCDs),organic light emitting diodes(OLEDs)because of their high transparency and high electrical conductivity.Indium tin oxide(ITO)is currently the most widely used type of electrode material in photovoltaic devices,but due to its high price,shortage of indium resources and brittleness and other factors,it urgently needs to be replaced.The top electrode of the photovoltaic device is usually prepared by a vacuum evaporation method.This coating method uses expensive equipment,takes time to prepare the device,and causes waste of materials,which greatly increases the cost of the photovoltaic device.And it has restricted its development towards large areas.There are great prospects for the preparation of photovoltaic devices using the full-solution process.Firstly,the cost of materials will be reduced.Secondly,the process is simple.Thirdly,large areas can be achieved.Therefore,the printed electrode is a key technology for realizing the photovoltaic devices using all-solution method.Since the silver nanowire transparent conductive film can maintain the lowest square resistance under the same light transmittance,excellent bending performance and cost advantages,it is considered to be the most promising next-generation transparent electrode.This dissertation aims to use inkjet printing to fabricate transparent electrodes based on silver nanowires as perovskite photovoltaic cells,systematically studied the selection of silver nanowire conductive inks,the influence of inkjet printing process on the performance of photovoltaic devices.The device structure is optimized to improve the device performance.Results and conclusions are summarized as following:(1)Research and performance characterization of inkjet printed silver nanowires as top electrodes for transparent perovskite solar cells.Firstly,the silver nanowire size,ink solvent,and ink concentration were screened.After that,the process parameters were optimized for the parameters such as pulse shape,dot pitch,and substrate heating temperature.Finally,the optimal ink was determined as follows: The silver nanowires of the isopropanol solvent had a diameter of 35 nm,a length of 20 μm,and a concentration of 1 mg/m L.The dot pitch is optimized at 60 μm and the substrate heating temperature is 40°C.Based on the above results,the conductivity and permeability of the silver nanowire film prepared by ink jet printing and the effect of the ink on the device film were systematically studied.Then,the silver nanowire was printed and prepared as a transparent perovskite solar cell.The results of the study indicate that the interfacial layer plays a crucial role in the process of printing silver wire top electrodes.When the silver nanowires are directly printed on the fullerene electron transport layer(PC61BM),the silver nanowires react with the halogen ions in the perovskite,so that the device efficiency is very low.By introducing a layer of polyethylenimine(PEI)on the fullerene electron transport layer,on the one hand,the injection barrier between PC61 BM and the silver nanowire electrode is greatly reduced.More importantly,PEI inhibits chemical etching of silver nanowires to the underlying film.The introduction of PEI greatly improved the device performance and stability,and finally achieved a transparent perovskite cell with an efficiency of 14.2% and a visible light transmittance of 21.2%.(2)Ink-jet printing silver nanowires as the bottom electrode to prepare a highly efficient and flexible perovskite solar cell.Using the advantage of inkjet printing technology in device preparation,combined with the advantages of silver nanowires in the preparation of transparent electrodes,silver nanowire electrodes were prepared on flexible and rigid substrates respectively,and the electrodes under different printing parameters were characterized.The optimized silver nanowire transparent conductive film is preferred.In order to improve the roughness of silver nanowires and inhibit the reaction of halogen ions and silver nanowires,m-PH1000(modified-PEDOT:PSS Clevious PVP AI PH1000),m-FCE(modified-PEDOT:PSS Clevious PVP AI FCE)were selected as the smooth and protective layer of silver nanowires,respectively.The finally obtained efficiency is 13%,on this basis,we use inkjet printing method to prepare a real fully-processed flexible perovskite solar cell and the cell finally achieved a photovoltaic conversion efficiency of 10.4%.