Fluorescent Phase-Pure Zero-Dimensional Perovskite-Related Cs4PbBr6 Microdisks: Synthesis and Single-Particle Imaging Study.

Quantum-confined perovskites are a new class of promising materials in optoelectronic applications. In this context, a zero-dimensional perovskite-related substance, Cs4PbBr6, having high exciton binding energy can be an important candidate, but its photoluminescence (PL) is a topic of recent debate. Herein, we report an ambient condition controlled synthesis of Cs4PbBr6 microdisks of different shapes and dimensions which exhibit fairly strong green PL (quantum yield up to 38%, band gap ∼2.43 eV) in the solid state. Using confocal fluorescence microscopy imaging of the single particles, we show that the fluorescence of Cs4PbBr6 microdisks is inherent to these particles. Fluorescence intensity and lifetime imaging of the microdisks reveals significant spatial heterogeneity with a bright central area and somewhat dimmer edges. This intensity and lifetime distribution is attributed to enhanced trap-mediated nonradiative deactivation at the edges compared to the central region of the microdisks. Our results, which unambiguously establish the PL of these Cs4PbBr6 and suggest its possible origin, brighten the potential of these materials in photon-emitting applications.