Colloid driven low supersaturation crystallization for atomically thin Bismuth halide perovskite

It is challenging to grow atomically thin non-van der Waals perovskite due to the strong electronic coupling between adjacent layers. Here, we present a colloid-driven low supersaturation crystallization strategy to grow atomically thin Cs3Bi2Br9. The colloid solution drives low-concentration solute in a supersaturation state, contributing to initial heterogeneous nucleation. Simultaneously, the colloids provide a stable precursor source in the low-concentration solute. The surfactant is absorbed in specific crystal nucleation facet resulting in the anisotropic growth of planar dominance. Ionic perovskite Cs3Bi2Br9 is readily grown from monolayered to six-layered Cs3Bi2Br9 corresponding to thicknesses of 0.7, 1.6, 2.7, 3.6, 4.6 and 5.7 nm. The atomically thin Cs3Bi2Br9 presents layer-dependent nonlinear optical performance and stacking-induced second harmonic generation. This work provides a concept for growing atomically thin halide perovskite with non-van der Waal structures and demonstrates potential application for atomically thin single crystals' growth with strong electronic coupling between adjacent layers. It is challenging to grow atomically thin non-van der Waals perovskites due to strong electronic coupling between adjacent layers. Here authors present the growth of perovskite single crystal nanosheets using a low supersaturation crystallisation strategy.

Automated summary

A colloid-driven low supersaturation crystallization strategy is used to successfully grow atomically thin Cs3Bi2Br9. This approach leverages the colloid solution to induce initial heterogeneous nucleation in a low-concentration supersaturation state. The results demonstrate the growth of atomically thin Cs3Bi2Br9 from monolayered to six-layered structures. This work provides a novel method for growing halide perovskite crystals with non-van der Waals structures and shows potential applications for atomically thin single crystal growth with strong electronic coupling between adjacent layers.