Effects of the Phase Spatial Distribution on the Intrinsic Carrier Dynamics in Quasi-2D Perovskite Films

2D Ruddlesden–Popper (RP) perovskites have drawn intensive attention due to their unique stability and optoelectronic properties. However, the further improvement of optoelectronic properties is hindered by the complex carrier dynamics resulted from random distribution of 2D (small- n ) and 3D ( n = ∞) phases. Herein, the effects of the phase distribution on the intrinsic carrier dynamics in (PEA) 2 (MA) 3 Pb 4 I 13 films were systematically studied using highly sensitive transient absorption spectroscopy (TAS). The (PEA) 2 (MA) 3 Pb 4 I 13 films with 2D/3D bulk heterojunctions and 3D (MAPbI 3 )/2D-3D mixed phase planar heterojunctions were prepared, respectively. Our results show that electrons transfer from 2D phases to the 3D phase in the non-carrier density-dependent region, but not between 2D phases in the 2D-3D mixed phases. Our investigations reveal that the carrier transport in quasi-2D perovskite films is primarily determined by the spatial distribution of the 2D phases. The desired phase distributions for the efficient carrier transport were proposed based on the TAS results.