Solid-liquid interface synthesis of selective (111)-oriented Cs<sub>2</sub>AgBiBr<sub>6</sub> perovskite crystals.

Abstract

Achieving the preferred orientation of specific facets is crucial for regulating the anisotropic physical properties of crystal materials and optimizing the performance of semiconductor optoelectronic devices. However, the intrinsic challenges lie in precisely controlling the growth kinetics of crystal facets and suppressing defects during the spontaneous crystallization processes. Herein, we report the microdroplet interface synthesis of Cs₂AgBiBr₆ single crystals with controlled orientations. By selectively reducing the nucleation barrier of (111) facets via modulation of the solid-liquid interface energy, the random (100)/(110)/(111) orientations are transformed into a selective (111)-preferred orientation. Further, thermal annealing is demonstrated to effectively improve crystal quality by releasing lattice strain and promoting octahedral reordering. Both theoretical calculations and experiments validate the advantages of (111)-oriented facets with higher ionic migrate energy and lower defect density than (100) and (110) facets, which result in better endurance to moisture and light irradiation. Besides, photodetectors based on the (111) facets exhibit superior performance to (100) and (110) facets. This work highlights the crucial role of interface energy in directing crystallographic orientation, providing theoretical basis and design strategies for the precise manipulation of crystal facets.