Morphology‐controlled Cs₂SbBr₆ crystals are synthesized by Bi‐ and Ag‐substitution of the precursor solution. X‐ray diffraction (XRD) together with Raman spectroscopy confirms the lattice tilting and symmetry changes with the dominant appearance of higher index facets by Bi substitution. Ag substitution does not induce crystal symmetry changes in the Cs₂SbBr₆ (B = Sb or Bi) phase, but results in highly defective structures hindering the formation of a smooth surface during the crystal growth. Successful substitution of Bi and limited substitution of Ag into Cs₂SbBr₆ is also confirmed by energy dispersive X‐ray spectroscopy (EDX). This research provides design principles and practical examples of how to control the morphology of Cs₂SbBr₆ crystals with structural defects and multiphase formation.
