Localized State-Induced Enhanced Emission in Perovskite Nanocrystals

The luminescent mechanism of nano-sized materials with indirect bandgap and parity-forbidden transition has always been a critical issue in breaking through bottlenecks in traditional luminescent materials. The lack of understanding has resulted in great disputes regarding the origin of fluorescence in weak-transition nanocrystals (NCs). This paper proposes a new physical luminescence model, named as localized state-induced enhanced emission (LIEE), i.e., localized processes induced by size-limitation or partial doping, to explain the anomalous luminescence from non-luminescent state to luminescent state in various perovskite nanocrystals with indirect/direct bandgap or parity-forbidden transition. These findings provide a theoretical viewpoint to design efficient lead-free perovskite NCs and promote the development of fast optical transitions in luminescent materials.