Defect step controlled growth of perovskite MAPbBr₃ single crystal

Perovskite MAPbBr₃ (MA = CH₃NH₃⁺) single crystals were grown via the anti-solvent vapor-assisted crystallization method. The crystal growth process was optimized by adjusting the solution concentration and diluting the anti-solvent. The maximum size of the obtained crystal was 9 × 9 × 3 mm³. It shows that the MAPbBr₃ single crystal is a cubic structure, the space group is Pm\( \bar{3} \)m, and the lattice constant is 0.59062 nm. Furthermore, its energy band gap is approximately 2.23 eV. The atomic force microscopy results demonstrated that the growth process of MAPbBr₃ single crystal followed the defect step growth mechanism, which was controlled by the screw dislocations within the crystal. Based on the curling growth of a screw dislocation on the crystal surface, a spiral step was formed. After the step was rotated around the entire mesa, a higher step was generated. Repeatedly, the step growth of screw dislocation within the crystal came into being. Besides, some small pits were also observed on (100) plane of the MAPbBr₃ crystal. These pits hindered the movement of steps and affected the lattice arrangement around them, causing the structural mismatch and more defects within the crystals.