Application And Research Of Metal Oxide Electron Transport Materials In Perovskite Solar Cells

Among all kinds of new energy technologies,photovoltaic power generation is undoubtedly one of the most promising directions.In recent years,perovskite solar cells?PSCs?have attracted the whole world's ambition toward the solar energy utilization due to the soaring increase in device performance.Besides,simple solution processing methods as well as low production cost make PSCs good candidates for commercial applications.In general,the structure of PSCs is mainly composed of transparent conductive glass,electron transport layer,perovskite absorption layer,hole transport layer and metal electrode.As the traditional electron transport material,TiO₂ has low electron mobility and usually requires high temperature sintering to enhance conductivity,which increases the preparation cost and it is not compatible with ITO or flexible substrate for the futher practical application.Thus,designing new electron transport material of low cost is significantly important.The main focus of this paper is to study novel low-temperature processed metal oxides as electron transport materials so as to successfully prepare low cost and high efficiency PSCs.The main contents in this work include:1.Novel low-temperature processed SnO₂-TiO₂ composite layer was prepared by sol-gel method.Absorption spectra,cyclic voltammetry,photoluminescence spectra were characterized to indicate that the inorganic metal oxide composite layer brings perfect bandgap matching at the perovskite/FTO interface,which contributes to better charge extraction,and significantly reduced charge recombination.The SnO₂-TiO₂ composite films based PSCs acquire high PCE of 14.8%,which is higher than PCEs of devices based on sintered TiO₂ layer?12.4%?and individual SnO₂ layer?6.2%?.2.We try to use interface modification to prepare the electron transport layer instead of spin coating method.Via hydrolysis of low-concentration TiCl4 solution at 70 °C,an ultrathin and discrete TiO₂ layer?u-TiO₂?was grown on fluorine doped tin oxide?FTO?substrate,forming the electron selective contact with the photoactive perovskite film.Then,through optimization,we finally achieved the PCE of 13.42%,which is compared to the PSCs using conventional TiO₂ material?13.56%?.Different from the traditional sintered TiO₂ compact layer,u-TiO₂ is composed of amorphous and discrete nano TiO₂ particles.Contact angle,scanning electron microscope,transient photoluminescence spectrum,and electrochemical impedancemeasurements show that the surface of u-TiO₂ has better hydrophilicity,and the u-TiO₂ owns larger contact area and smaller contact resistance,which favors the growth of perovskite layer and fascinates electron transfer.