Self-Assembly Behavior of Perylene Bisimide Derivatives on a Perovskite Nanocrystal Surface

Cesium lead halide (CsPbX3, X = Cl, Br, I) perovskite nanocrystals (NCs) exhibit outstanding photosensitizing properties, owing to their large absorption cross-section and high photoluminescence quantum yields. Consequently, coassemblies with functional organic dyes can be used to establish energy conversion systems capable of sensitizing dyes. In coassembly, the self-assembly behavior of the dyes on the NC should be investigated because the photophysical properties of the dyes are influenced by the assembly conditions. However, the self-assembly behavior of dyes on the NC surfaces remains unclear. Herein, we report the self-assembly behavior of perylene bisimide (PBI) derivatives on the CsPbBr3 perovskite NC surface. Moreover, we revealed fluorescence resonance energy transfer (FRET) from the NC to the PBIs by an in-depth analysis of the photoluminescence spectra and decay curves. For the PBI derivative with one carboxyl group as an adhesion moiety to the NC, the PBI was adsorbed on the NC, and the resultant coassembly exhibited FRET from the NC to monomeric PBIs. By contrast, the PBI derivative with two carboxyl groups underwent pi-pi stacking on the NC surface, and the specific coassembly exhibited FRET from NC to assembled PBIs. The efficient self-assembly of PBI on the NC surface was induced by intermolecular hydrogen bonding between the carboxyl groups.