Controlled synthesis of zero-dimensional phase-pure Cs4PbBr6 perovskites crystals with high photoluminescence quantum yield

Cesium lead halide perovskites have been arise as a new promising materials for optoelectronic applications . On this basis, zero-dimensional inorganic perovskites, Cs 4 PbBr 6 can be an important candidate because of the excellent stability. However, obtaining the high photoluminescence quantum yield (PLQY) of phase-pure Cs 4 PbBr 6 Perovskites still remains a challenge. Here, we synthesized the phase-pure Cs 4 PbBr 6 crystals through a simple ligand-assisted, reprecipitation strategy under room-temperature. We altered the assisted ligands that used in the experiment synthesis, such as substitute dodecylamine for oleylamine, and obtained high near PLQY (95.1%) of phase-pure Cs 4 PbBr 6 Perovskites. We revealed the extra oleic acid (OA), such as the ratio of OA and dodecylamine for 10 : 1 $10:1$ , would improve their PLQY. Most importantly, we demonstrated the short lifetime decay is caused by the recombination of trapped exciton inside the crystal but the long lifetime decay is attributed to the recombination of the surface energy states, and provided a great comprehension in photophysical of Cs 4 PbBr 6 Perovskite materials.