Discrete composition control of two-dimensional morphologic all-inorganic metal halide perovskite nanocrystals

Metal halide perovskite nanocrystals (NCs) exhibit impressive optical and electronic properties, making them an important class of functional materials with promising applications in solar cells, light emitting diodes (LEDs), photodetectors, and photocatalysts. In addition to the widely studied 0-dimensional (0D) metal halide perovskite NCs, such as nanocubes, low dimensional perovskites, such as 2D all-inorganic perovskite (AIP) NCs, subsist with directionally relevant quantum confinement. These anisotropic NCs have the propensity to exhibit interesting optoelectronic properties that are exceedingly difficult to introduce into 0D systems, yet as of late are largely unexplored. In this review, we discuss the recent synthetic progress of 2D all-inorganic metal halide perovskite NCs with ABX₃ structure. Specifically, we highlight the discrete composition control of the cations (A and B sites) and anions (X site) by dopant incorporation and alloying in 2D metal halide perovskite NCs. We will also discuss more complex perovskite crystal structures, such as Ruddlesden–Popper double perovskites, and compare these materials to 0D perovskite systems. Ultimately, our work culminates in the future interests and perspectives of this field with a focus on the wide applicability of 2D systems and the large variance in structure capable with discrete compositional tuning.