Unveiling Facet-Controlled Energy Transfer from Individual Perovskite Nanocrystals to Dyes

Increasing the number of facets in CsPbBr 3 perovskite nanocrystals (PNCs) from 6 to 12 and 26─without significantly changing their surface area─markedly enhances energy transfer (ET) efficiency in PNC–dye assemblies, as shown by solution-phase ensemble studies. This enhancement stems from stronger dye binding in facet-rich PNCs, which is supported by fluorescence correlation spectroscopy (FCS). Single-particle ET measurements, however, reveal comparable per-dye ET efficiencies across PNCs with varying facet counts. The transfer is governed by a Dexter mechanism, facilitated by dyes with strong anchoring groups that penetrate the ligand shell and bind directly to the NC surface, thereby eliminating the requirement for the spectral overlap typically necessary in resonant ET. Further studies show that the higher binding affinities of extra-faceted PNCs enable more efficient carrier extraction. Collectively, these findings highlight facet engineering as a versatile strategy to modulate interfacial interactions and enhance performance in applications ranging from photocatalysis to sensing and light harvesting.