Study On The Interfacial Layers For Electrodes Of Perovskite Solar Cells

In recent years,new perovskite solar cells have achieved rapid development.The photoelectric conversion efficiency has increased from the initial 3.8%to over 20%,which is equivalent to the efficiency of silicon-based solar cells commercialized for many years.Therefore,perovskite solar cells are considered as one of the most promising new solar cells for commercialization.In perovskite solar cells,the electron transport layers as the interfacial layers between the transparent electrodes and perovskite,and has the functions of electron collection,electron transmission,and electron-hole inhibition.Therefore,the performance of the electron transport layers affects the performance of perovskite solar cells to a certain extent.On the other hand,on the basis of ensuring photoelectric conversion efficiency,reducing cost and improving stability have gradually become the development direction of perovskite solar cells.In this paper,we take perovskite solar cells as the research object,focusing on the influence of interface contact between perovskite layers and electrodes on device performance.The effects of different particle sizes on the performance of planar perovskite solar cells were studied by doping TiO₂ nanoparticles with different particle sizes in the TiO₂ electron transport layers.On the other hand,by developing a low temperature carbon slurry to make the back electrodes of the perovskite solar cell,the interface contact between the carbon electrodes and the perovskite layers was studied,so as to obtain a more stable perovskite solar cells.The main contents are as follows:1.Perovskite solar cells with planar structure are popular for their simple device structure and small hysteresis effect.Compared with traditional mesoporous devices,planar devices have no TiO₂ porous support layers,and the functions of electron extraction,electron transport and hole plugging are completed by dense TiO₂ electron transport layers.Therefore,the properties of the dense TiO₂ electron transport layers have a crucial impact on the performance of solar cells.In this work,we developed a mixed spray pyrolysis method,in which TiO₂ nanoparticles of different particle sizes were added into the precursor solution to prepare a dense TiO₂ electron transport layers.The optimized nanoparticle size is 60 nm,and the photoelectric conversion efficiency of the corresponding device is 16.7%,while that of the device without nanoparticles is 9.9%,so the device efficiency after adding nanoparticles is significantly higher than that of the device without nanoparticles.2.Compared with the perovskite solar cells with noble metal electrodes,carbon electrodes have attracted more and more attention from researchers due to their lower cost and simple manufacturing process.In this work,we developed a low temperature carbon slurry with graphite and carbon black as the main raw materials,and prepared carbon electrodes by screen printing method.Based on the device structure?FTO/dense TiO₂/mesoporous TiO₂/perovskite/carbon electrodes?,when the inorganic cavitation material CuSCN is added as the hole transport layers between perovskite and carbon electrodes,the hole extraction ability is improved,and the photoelectric conversion efficiency is increased from 7.3%to 11.8%.In order to further improve the device performance,we add a layers of carbon black between CuSCN and carbon electrodes to improve the interface contact.Through scanning electron microscope images,it can be clearly seen that small spherical particles of carbon black can be in close contact with CuSCN,which improves the charge collection ability of carbon electrodes and increases the efficiency from 11.8%to 15.5%.At the same time,compared with the gold electrodes device,the moisture stability and illumination stability of the carbon electrodes device are improved obviously.After aging for 2000hours,the device efficiency can still maintain 68.1%of the initial efficiency,while the device efficiency of gold electrodes is only 38.7%of the initial efficiency after aging.After 500 hours of light aging,the device efficiency can still maintain 63.6%of the initial efficiency,and the device efficiency of the gold electrodes is only 36.2%of the initial efficiency.