Two-dimensional Hybrid Perovskites: from Static and Dynamic Structures to Potential Applications.

Two-dimensional (2D) perovskites have received great attention recently due to their structural tunability and environmental stability, making them highly promising candidates for various applications by breaking property bottlenecks that affect established materials. However, in 2D perovskites, the complicated interplay between organic spacers and inorganic slabs makes structural analysis challenging to interpret. A deeper understanding of the structure-property relationship in these systems is urgently needed to enable high-performance tunable optoelectronic devices. Herein, we examine how structural changes, from constant lattice distortion and variable structural evolution, modeled with both static and dynamic structural descriptors, affect macroscopic properties and ultimately device performance. We report the effect of chemical composition, crystallographic inhomogeneity, and mechanical-stress-induced static structural changes and corresponding electronic band variations. Additionally, the structure dynamics are described from the viewpoint of anharmonic vibrations, which impact electron-phonon coupling and the carriers' dynamic processes. Correlated carrier-matter interactions, known as polarons and acting on fine electronic structures, are then discussed. Finally, we propose reliable guidelines to facilitate design to exploit structural features and rationally achieve breakthroughs in 2D perovskite applications. This review provides a global structural landscape of 2D perovskites, expected to promote the prosperity of these materials in emerging device applications. This article is protected by copyright. All rights reserved.