Efficient dispersion of organic fluorophores by size matching with a new di-functionalized spacer interleaved into layered double hydoxide

Abstract

Strongly luminescent when diluted in aqueous solution, Sulforhodamine B (SRB) is an organic fluorescent molecule suffering from aggregation caused quenching (ACQ) in its solid state. Its co-intercalation in very small quantities (0.12 mol%) in a layered double hydroxide (LDH) matrix with phenylenedipropionate (PPA) anions, a di-functionalized new spacer matching its size, is found to be highly effective, with more than 99% of the SRB molecules uptaken. The resulting hybrid material enables luminescence with an absolute quantum yield (PLQYabs) reaching 39% under UV excitation and even reaching 60% at its maximum. The dispersion of the luminescent hybrid powder constituted of SRB molecules intercalated into LDH platelets in silicone results in homogeneous composite films with loading as high as 40 wt.% useable as masterbatch. The optical properties are found to remain after thermal treatment up to 120°C with a decrease in PLQYabs of 5% only, making it a good candidate for the development of rare-earth-free phosphors.