Preparation And Photoelectric Properties Of TiO₂NRAs/ZrO₂/C Perovskite Solar Cells

Solar cells with perovskite(CH3NH3PbI3)as light-absorbing material have been widely studied in recent years,due to many advantages such as suitable band gap,good light-absorbing performance,simple synthesis and abundant raw materials.Hole-conductor-free full printing mesoscopic perovskite solar cells have a simple TiO2/ZrO2/C three-layer structure,which has the advantages of low cost,simple process and high stability.At present,there is a problem that the photoelectric conversion efficiency is lower than the mesoporous structure and planar structure.The electron transport layer plays an important role of the device and has a great influence on its performance.One-dimensional TiO2 nanorods(TiO2NRAs)can provide a direct path for electron transport,and the open pore ordered structure facilitates the filling and growth of perovskite crystals.In this paper,TiO2 nanorods were used as the electron transport layer to fabricate mesoscopic perovskite solar cells with TiO2NRAs/ZrO2/C structure,and related optimization and characterization were carried out.The main research contents and results of this article are as follows:(1)Preparation of TiO2NRAs/ZrO2/C perovskite solar cells.The rutile TiO2NRAs were prepared by hydrothermal method.The thickness of TiO2NRAs films was controlled by controlling the hydrothermal time.The effects of different thicknesses of TiO2NRAs films on the photoelectric properties of the device were studied.The results show that the current density,fill factor,and photoelectric conversion efficiency increase first and then decrease with increasing thickness of TiO2NRAs film.When the TiO2NRAs film is 1 ?m,the device obtained relatively high efficiency of 3.4%.(2)Solvent annealing growth of perovskite crystals in TiO2NRAs/ZrO2/C structure under high humidity(RH?50%).The perovskite crystals were grown in the TiO2NRAs/ZrO2/C structure using the solvent annealing process and the ordinary annealing process.The effects of the two processes on the device performance were compared.The results show that the perovskite crystals grown in ordinary annealing process will produce PbI2 and mesophase,and will be filled in TiO2NRAs unevenly.Solvent annealing can produce high-quality perovskite crystals without miscellaneous phases.The electron recombination rate inside the device is reduced,which increasing photoelectric conversion efficiency to 6.2%.(3)Cl-regulated growth of TiO2NRAs and interface kinetics of the device.The porosity of TiO2 nanorods was controlled by adjusting the Cl-concentration in the hydrothermal precursor solution.The effect of different Cl-concentrations on the device performance was studied.The results show that Cl-can effectively inhibit the lateral growth of TiO2 nanorods.With the increase of Cl-concentration,the porosity of TiO2NRAs increases gradually,and the efficiency of the device increases first and then decreases.The highest efficiency is 9.13%.Using open-circuit voltage decay test and electrochemical impedance spectroscopy explained the reason for its high efficiency.The device(4%NaCl)obtained the highest efficiency,because the TiO2NRAs/FTO interface charge transfer resistance is small and the interface resistance of TiO2NRAs/CH3NH3Pbl3 is larger...