A Demulsification-Crystallization Model for High-Quality Perovskite Nanocrystals.

A room-temperature technique with all-nonpolar-solvent, which circumvents the sensitivity of ionic perovskite to polar solvent, has become attractive for the synthesis of metal halide perovskite nanocrystals (PNCs). However, the lack of understanding of the inner mechanism, especially for the state of the precursor and the crystallization process of the PNCs, hinders further development of this technique. Here, through systematic study of the Pb precursor and in situ characterization of the PNCs, it is revealed that the reverse micelle nature of the Pb precursor exactly creates a novel demulsification-crystallization (D-C) model, namely, a two-stage nucleation is divided by a demulsification process for the PNCs. On this basis, a top efficiency for green light-emitting diodes based on PNCs is obtained with a maximum external quantum efficiency of 22.5% through tailoring the D-C model using a multiple-acid-anion synergistic assisted strategy to obtain high-quality PNCs. Beyond the high efficiency, the work paves the way for diverse ideas in PNC synthesis.