Probing the ultrafast charge carrier dynamics in double-layered mixed halide perovskite photovoltaics

In this work, we investigate the ultrafast charge carrier dynamics in the double-layered architecture mixed halide (DHA) perovskite photovoltaic devices by ultrafast pump-probe transient absorption spectroscopy (TAS). The measured TAS results show the perovskite solar cell consists of SnO2/(FAPbI3)1-x(MAPbBr3)x/HTAB has stronger transient absorbance with photoinduced bleaching at 750 nm and photoinduced absorption in the range of 550-700 nm. The lifetime of DHA perovskite observed from TAS is approximately 46 µs in conjunction with the electron injection discovered within the first 150 fs, indicating the charge carriers would be easily extracted. Besides, we measured a high power-conversion-efficiency of the DHA perovskite solar cell (PSC) of 21%. Hence, understanding the ultrafast charge carrier dynamics in PSC by pump-probe TAS provides detailed insights into the advanced working mechanism. The results open a door for the development of high-performance perovskite photovoltaics.