Colloidal Synthesis of CH3NH3PbBr3 Nanoplatelets with Polarized Emission through Self‐Organization

We report a combined experimental and theoretical study of the synthesis of CH₃NH₃PbBr₃ nanoplatelets through self‐organization. Shape transformation from spherical nanodots to square or rectangular nanoplatelets can be achieved by keeping the preformed colloidal nanocrystals at a high concentration (3.5 mg mL⁻¹) for 3 days, or combining the synthesis of nanodots with self‐organization. The average thickness of the resulting CH₃NH₃PbBr₃ nanoplatelets is similar to the size of the original nanoparticles, and we also noticed several nanoplatelets with circular or square holes, suggesting that the shape transformation experienced a self‐organization process through dipole–dipole interactions along with a realignment of dipolar vectors. Additionally, the CH₃NH₃PbBr₃ nanoplatelets exhibit excellent polarized emissions for stretched CH₃NH₃PbBr₃ nanoplatelets embedded in a polymer composite film, showing advantageous photoluminescence properties for display backlights.