Evaporation-induced nano- to micro-sized transformation of photoluminescent Cs4PbBr6 crystals

Abstract

Bulk zero-dimensional (0D) rhombohedral perovskite Cs₄PbBr₆ crystals grown into microsized ones exhibit bright green photoluminescence (PL) ranging from 510 to 530 nm and have attracted much attention due to their potential applications in photovoltaic and white light-emitting diodes (WLEDs). Here, we report blue luminescence of Cs₄PbBr₆ nanosized crystals (NCs) (∼3 nm) at 467 nm in highly volatile acetone (CP) solution in the presence of organic amines with carbon chain lengths ranging from 4C to 8C at room temperature. Subsequently, the Cs₄PbBr₆ NCs gradually grew into microsized crystals (MCs) (∼2 μm) and the emission wavelength shifts to 515 nm within 40–100 min. This is attributed to the evaporation of organic amines along with CP on the surfaces of Cs₄PbBr₆ crystals. The final grown Cs₄PbBr₆ MCs are free of any ligands with photoluminescence quantum yields (PLQYs) up to 93.3% and show a superior moisture resistance. The spontaneous growth of ligand-free Cs₄PbBr₆ crystals spans from the nanometer to the micrometer scale and causes changes in quantum confinement for fundamental new insights into the crystal growth dynamics of the perovskites and exhibits promising applications in WLEDs.