Extremely efficient internal exciton dissociation through edge states in layered 2D perovskites

作者：Jean‐Christophe Blancon, Hsinhan Tsai, Wanyi Nie, Constantinos C. Stoumpos, Laurent Pédesseau, Claudine Katan, Mikaël Képénékian, Chan Myae Myae Soe, Kannatassen Appavoo, Matthew Y. Sfeir, Sergei Tretiak, Pulickel M. Ajayan, Mercouri G. Kanatzidis, Jacky Even, Jared Crochet, Aditya D. Mohite · 发表于：Science · 年份：2017 · DOI：10.1126/science.aal4211 · 被引用次数：1093 · 研究领域：Perovskite Materials and Applications、Electronic and Structural Properties of Oxides、Quantum Dots Synthesis And Properties

Understanding and controlling charge and energy flow in state-of-the-art semiconductor quantum wells has enabled high-efficiency optoelectronic devices. Two-dimensional (2D) Ruddlesden-Popper perovskites are solution-processed quantum wells wherein the band gap can be tuned by varying the perovskite-layer thickness, which modulates the effective electron-hole confinement. We report that, counterintuitive to classical quantum-confined systems where photogenerated electrons and holes are strongly bound by Coulomb interactions or excitons, the photophysics of thin films made of Ruddlesden-Popper perovskites with a thickness exceeding two perovskite-crystal units (>1.3 nanometers) is dominated by lower-energy states associated with the local intrinsic electronic structure of the edges of the perovskite layers. These states provide a direct pathway for dissociating excitons into longer-lived free carriers that substantially improve the performance of optoelectronic devices.