Gold-loaded microspheres: Via carbosilane-thioether dendrimers as stabilizers and their performance in layer-controllable photonic crystals

Gold nanoparticle (Au NP) incorporated photonic crystals (PCs) have been extensively studied due to the intricate interplay between the surface plasmon resonance of Au NPs and the periodic nanostructure of PCs. Herein, we successfully synthesized Au NP decorated poly(styrene-co-(generation 3 carbosilane-thioether vinyl-terminated dendrimer)) (P(st-co-G3Vi)) microspheres via in situ reduction of Au ions based on the strong coordination between the Au ions and the sulfur atom in G3Vi dendrimers. These composite Au-doped microspheres demonstrate a bumpy surface topography, which gives rise to a higher hydrophobicity and could effectively suppress the formation of an ubiquitous coffee-ring during the drying process of a colloidal suspension. More importantly, layer-controllable PCs were constructed with Au-doped microspheres by combining the Langmuir-Blodgett method with a layer-by-layer stacking strategy. By manipulating the stacking layers and diameters of microspheres, multifarious PCs with different photonic band gaps and reflection intensities were obtained, which can serve as an effective substrate for amplified quantum dot fluorescence. Further investigation reveals that fluorescence could be significantly pronounced by five-layer PCs. This work offers a facile and reproducible strategy to prepare Au NP incorporated PCs by in situ synthesis of Au NPs within dendrimer-functionalized microspheres, resulting in an enhancement of quantum dot fluorescence, which will lead to promising applications in energy-saving optoelectronic devices.