Enhanced charge carrier lifetime in layered 2D hybrid perovskites

Lower dimensional layered perovskite exhibited better environmental stability than 3D organic-inorganic hybrid perovskite materials such as methylammonium lead iodide (MAPbI₃). Due to the reduced dimensionality, one drawback of these layered 2D perovskite is the reduced charge carrier mobility. Currently, using layered 2D perovskite materials, no improvement in solar cell performance has been reported. In this study, we synthesized layered 2D lead-halide perovskite samples using different ratios of t-butylammonium and methylammonium as the organic cation, creating a set of samples spanning the 3D to 2D transition. We used time resolved terahertz conductivity measurements, a non-contact conductivity probe, to study both charge carrier mobility and lifetime in these materials. We confirmed the reduced charge carrier mobility but found enhanced carrier lifetime, indicating a possibility of finding optimal composition to maximize carrier diffusion length. The increased carrier lifetime supports efficient exciton dissociation and long-lived free carriers recently reported on other 2D Ruddlesden-Popper perovskites. Lastly, we compared the device performance of the 2D perovskite solar cells with the charge carrier dynamics measured.