From halide perovskite nanocrystals to supercrystals: fundamentals and applications.

Halide perovskite supercrystals, also known as superlattices, are electronically coupled low-dimensional materials, such as nanocrystals, quantum dots, or nanoplatelets that offer collective optical and electronic properties distinct from those of their constituents. The intrinsic dielectric properties and defect tolerance of halide perovskites make their supercrystals superior to metal chalcogenide supercrystals. The physicochemical properties of ligands and the shape and size uniformity of the constituents determine the overall size, shape, and electronic and optical properties of these supercrystals, where excitons interact across long distances through phase coherence and dipole coupling, inducing enhanced and narrow-band emission, including superfluorescence, superradiance, amplified spontaneous emission, and lasing. These emergent optical and electronic properties make halide perovskite supercrystals promising for brilliant LEDs, low-threshold lasers, high-efficiency solar cells, and broadband photodetectors. This article provides a state-of-the-art overview of halide perovskite supercrystals, addressing the critical gap between their structure-property relationship and linking the fundamental mechanism of electronic coupling with their emergent optoelectronic properties.