Luminescence resonance energy transfer based on β-NaYF4:Yb,Er nanoparticles and TRITC dye

β-NaYF4:Yb,Er nanoparticles (NPs) are one of the most efficient upconversion materials, which can convert near-infrared light to higher-energy light through multiple photon absorptions or energy transfer. In addition, they may be attractive alternative donors for luminescence resonance energy transfer (LRET) studies, because of their sharp absorption and emission profiles, high quantum yields, large anti-stokes shifts, long lifetime, low toxicity, and superior photo-stability. In principle, many problems of fluorescence resonance energy transfer (FRET), such as excitation of acceptors, emission overlaps between donors and acceptors, high background noise, potential toxicity, and instability, can be overcome using β-NaYF4:Yb,Er NPs as energy donors. Because the organic coating induced separation can significantly reduce the energy transfer efficiency and aqueous FRET system is difficult to be applied in devices, we demonstrate a novel NP-dye LRET system in solid state. The emission of the β-NaYF4:Yb,Er NPs at 539 nm overlaps with the absorption of the tetrametrylrhodarnine isothiocyante (TRITC), satisfying the requirement of LRET process. Since TRITC molecules are adsorbed on the β-NaYF4:Yb,Er NPs by an electrostatic interaction, the interaction distance is suitable for LRET without any further modulation. The resultant solid LRET system is ready for the further applications for devices.