Performance Of Mesoporous PSCs Based On TiO₂ Modified With CdO Quantum Dot

Perovskite solar cells（PSCs）have attracted much attention due to the excellent light absorption,high photoelectric conversion efficiency,and gradually show great commercial prospects,which become the focus of the current photoelectric field in recent years.Among the components of PSCs,the electron transport layer（ETL）,as the part that directly contacts with the perovskite film,not only supports the perovskite film,but also transmits electrons,which plays an important role in the device.Therefore,the improvement of ETL is still a resultful way to improve the efficiency PSCs.In this paper,oxidation state quantum dot Cd O（Cd O-QDs）was proposed and prepared for the first time.On the basis of TiO₂films with two different morphologies,TiO₂surface was modified by doping quantum dot Cd O to prepare composite ETL,and to explore the influence of composite film as ETL on the photoelectric properties of perovskite.The specific research contents are as follows:Cd O quantum dot/TiO₂mesoporous film（Cd O-QDs/TiO₂-MF）was prepared by Successive Ionic Layer Adsorption and Reaction（SILAR）-Sintering method as the ETL,and the phase,morphology and optical properties of the quantum dot composite film were analyzed,as well as the effect of quantum dot on the interface defects of TiO₂.The perovskite layer was prepared by two-step method and was assembled the PSC,and the effect of quantum dot composite film as ETL on photoelectric performance of PSC was investigated.It is found that the doping of Cd O-QDs is beneficial to improve the electron transport layer band structure,reduce the surface defects of TiO₂-MF and the recombination of electron-hole.The doping content of Cd O-QDs was controlled by the impregnation circulation times,and the ETL was further optimized.After three impregnation cycles,the photoelectric conversion efficiency was finally 6.94%,which was about 62.91%higher than that of pure TiO₂.TiO₂nanocrystals array（TiO₂-NA）were prepared by hydrothermal method,and Cd O-QDs/TiO₂-NA were prepared by doping Cd O-QDs with SILAR-Sintering method to explore the surface modification of TiO₂-NA by Cd O-QDs.The composite films ETL with different rod lengths was controlled by the hydrothermal times,and the effect of their thickness on the photoelectric performance of PSC was investigated.Compared with pure TiO₂-NA,Cd O-QDs/TiO₂-NA have significantly improved short-circuit current and open-circuit voltage,and it is believed that Cd O-QDs composite can effectively improve the surface defects of TiO₂-NA.By comparing the SEM images of Cd O-QDs/TiO₂-NA based perovskite films with different rod lengths,it was found that the thickness of the array had an effect on the growth and crystallization of the perovskite film.It was found that when the hydrothermal time was 120 min,the optimal photoelectric conversion performance of the 460 nm composite film prepared as the ETL was 11.49%.