Defect step controlled growth of perovskite MAPbBr(3) single crystal

摘要

Perovskite MAPbBr(3) (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 9x9x3mm(3). It shows that the MAPbBr(3) single crystal is a cubic structure, the space group is Pm3m, and the lattice constant is 0.59062nm. Furthermore, its energy band gap is approximately 2.23eV. The atomic force microscopy results demonstrated that the growth process of MAPbBr(3) 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 MAPbBr(3) 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.