All‐Inorganic Perovskite Single‐Crystal Photoelectric Anisotropy

Abstract Engineering surface structure can precisely and effectively tune the optoelectronic properties of halide perovskites, but are incredibly challenging. Herein, the design and fabrication of uniform all‐inorganic CsPbBr 3 cubic/tetrahedral single‐crystals are reported with precise control of the (100) and (111) surface anisotropy, respectively. By combining with theoretical calculations, it is demonstrated that the preferred (100) surface engineering of the CsPbBr 3 single‐crystals enables a lowest surface bandgap energy (2.33 eV) and high‐rate carrier mobility up to 241 μm 2 V ‐1 s ‐1 , inherently boosting their light‐harvesting and carrier‐transport capability. Meanwhile, the polar (111) surface induces ≈0.16 eV upward surface‐band bending and ultrahigh surface defect density of 1.49 × 10 15 cm ‐3 , which is beneficial for enhancing surface‐defects‐catalyzed reactions. The work highlights the anisotropic surface engineering for boosting perovskite optoelectronic devices and beyond.