Single-Component Oligomer Nanoparticle-Based Size-Dependent Dual-Emission Modulation

Multichromophoric oligomers offer a versatile platform for nanoparticle multicolor fluorescent modulation. A donor-acceptor-donor (D-A-D) type oligomer (DDBTD), with blue emitting antenna and red emitting core, is chosen to assemble into fluorescent colloidal nanoparticles (FCNs) using a nanoprecipitation method. By modulating the DDBTD concentrations in good solvent, the DDBTD nanoparticles with average diameters ranging from sub-10 to 300 nm are obtained by the nanoprecipitation process in aqueous solution. Interestingly, multicolor photoluminescence (PL) can be realized from bright blue (∼440 nm) to rose red (∼630 nm) based on FCNs size control. The size-dependent PL originates from the aggregation-enhanced fluorescence resonance energy transfer (FRET) from diphenyl-aminofluorenyl antenna unit (blue emitter) to benzothiadiazole-based core (red emitter). Furthermore, the lifetime measurement of the FCNs in excited state shows a size-dependent behavior, which confirms that the size-dependent multicolor PL modulation is adjusted by FRET in the nanoscale oligomer. This work highlights the potential of the single-component multichromophoric oligomer FCNs for luminescent modulation applications.