3D photonic crystals from highly monodisperse FRET-based red luminescent PMMA spheres
Red-luminescent PMMA spheres containing a Förster resonance energy transfer (FRET) pair were synthesized via a two-step polymerization method. Two reaction parameters, time and monomer volume, are scanned in order to tune the sphere diameter in the 250–500 nm range. Further the polydispersity of the spheres is kept low, at ca. 3%, regardless of sphere diameter or dye concentration. A thorough optical characterization via spectroscopy and time resolved measurements shows a FRET efficiency of over 40% before concentration quenching effects take place, allowing for a precise tuning of their emission in the red region of the visible spectrum. The high quality of these spheres makes them suitable to fabricate self-assembled 3D photonic crystals which act as photonic environment to modify the spectral properties of the FRET pair via Bragg diffraction.