Intriguing Ultrafast Charge Carrier Dynamics in Two-Dimensional Ruddlesden–Popper Hybrid Perovskites

Two-dimensional (2D) Ruddlesden–Popper (RP) hybrid perovskites are among the most promising semiconductor candidates for next-generation highly efficient optoelectronic devices due to their impressive optical and transport properties. More importantly, 2D hybrid perovskites exhibit much higher structural and chemical stability against moisture and light radiation levels than their 3D counterparts, indicating a wide range of potential applications and commercialization. The highly ordered multiple-quantum-well structures of 2D RP perovskites give rise to several optoelectronic properties that can be effectively tuned by compositional engineering of organic spacers and inorganic layer thicknesses. In this Perspective, we review recent studies of charge carrier dynamics in 2D RP perovskites. More specifically, we focus on understanding how organic cations and the number of inorganic layers govern the ultrafast charge carrier dynamics in 2D RP perovskites. We also highlight our recent work on hot-carrier cooling dynamics, Rashba band splitting, and narrowband and broadband emissions in various 2D RP hybrid perovskites. We also provide a perspective on the future studies of 2D RP perovskites, including structure–property relationships, and remaining questions on the charge carrier dynamics, including hot-carrier extractions.