Charge-Carrier Dynamics and Crystalline Texture of Layered Ruddlesden–Popper Hybrid Lead Iodide Perovskite Thin Films

Solution-processable organic metal halide Ruddlesden–Popper phases have shown promise in optoelectronics because of their efficiencies in solar cells along with increased material stability relative to their three-dimensional counterparts (CH3NH3PbI3). Here, we study the layered material butylammonium methylammonium lead iodide (C4H9NH3)2(CH3NH3)n−1PbnI3n+1 for values of n ranging from 1 to 4. Thin films cast from solution show a gradual change in the crystalline texture of the two-dimensional lead iodide layers from being parallel to the substrate to perpendicular with increasing n. Contactless time-resolved microwave conductivity measurements show that the average recombination rate order increases with n and that the yield–mobility products and carrier lifetimes of these thin films are much lower than that of CH3NH3PbI3, along with increased higher-order recombination rate constants.