Spontaneous morphology reconfiguration of luminescent CH 3 NH 3 PbBr 3 perovskites from monodispersed nanocrystals to discontinuous rings by dewetting-triggered solute migration

Morphology engineering is vital for tuning electronic and optical properties of perovskite nanocrystals (NCs). Though many 1D, 2D and 3D perovskite NCs have been prepared, perovskite rings are not reported. This work reported the preparation of perovskite rings by a simple method of dewetting perovskite NCs solution on the glass slide. Our results indicate that perovskites NCs can change their morphology from the starting nano-sized spherical shape to intermediate molecules/ions and finally to micron-sized perovskite rings during the dewetting process. The alteration of NCs–molecules–rings is driven by the dewetting-induced alteration of solvent environment for perovskite from the initial insoluble mixture of N,N-dimethylformamide (DMF) and toluene (1:50 v/v), to intermediate soluble DMF and finally to the glass slide without solvent. During the decomposing process from starting NCs to molecules/ions, the original oleic acid ligands of perovskite NCs will be released. These oleic acid surfactants will form ligand-stabilized gas bubbles, which act as in situ templates for reshaping of perovskite ring shape from molecules/ions.