Efficient Luminescence from CsPbBr₃ Nanoparticles Embedded in Cs₄PbBr₆

Cs₄PbBr₆ is regarded as an outstanding luminescent material with good thermal stability and optical performance. However, the mechanism of green emission from Cs₄PbBr₆ has been controversial. Here we show that isolated CsPbBr₃ nanoparticles embedded within a Cs₄PbBr₆ matrix give rise to a "normal" green luminescence while superfluorescence at longer wavelengths is suppressed. High-resolution transmission electron microscopy shows that the embedded CsPbBr₃ nanoparticles are around 3.8 nm in diameter and are well-separated from each other, perhaps by a strain-driven mechanism. This mechanism may enable other efficient luminescent composites to be developed by embedding optically active nanoparticles epitaxially within inert host lattices.