Energy Transfer from a Perovskite Nanocrystal to Cyanine Dyes Depending on Spectral Overlap Revealed by a Single-Particle Spectroscopy

Investigation of the energy transfer (ET) between perovskite nanocrystals (PNCs) and organic dyes is crucial because PNCs are suitable donor materials for creating photosensitizer systems. In this study, we investigated the relationship between a singlet ET mechanism and spectral overlap using CsPbBr₃ PNC-cyanine dyes─Cy3 and Cy5. We prepared PNC-dye linkage systems and investigated the ET at the single-PNC levels. The results of our study reveal that efficient ET occurs via fluorescence resonance ET (FRET) in the PNC-Cy3 system. Even in the PNC-Cy5 system, where the spectral overlap integral is 1 order of magnitude smaller than in the PNC-Cy3 system, efficient ET is observed, suggesting the occurrence of Dexter-type ET (DET). These results clearly demonstrate the change in the ET mechanism between FRET and DET depending on the spectral overlap. These findings are important for understanding exciton dynamics in PNC-organic molecule hybrid systems.