Size-preset Synthesis of Highly Monodisperse Silica Spheres for Self-Assembly of Photonic Crystals with Narrow Band Width

Monodisperse silica nanospheres (SNPs) are excellent basic materials for the construction of photonic crystals (PCs). However, size-preset synthesis of monodisperse SNPs with a polydispersity below 2% remains a serious challenge. Herein presented is a facile method to size-predictably synthesize highly monodisperse SNPs with size-preset up to 1000 nm and polydispersity < 2%. The key idea is to controllably grow the size-preset SNPs from uniform silica spheres or seeds. A biphasic reaction was adopted to synthesize as uniform silica seeds as possible, followed by an appropriate addition rate of tetraethylorthosilicate, to minimize the impact of uncontrollable nucleation reaction. The method was validated to produce ideal SNPs for easy assembly of high-quality PCs with an ultra-narrow band width, down to 13 nm, similar value to the previous report. The method features production scalable and size predicable. This enables the synthesis of customized SNPs to widen their applications, but not limited to PCs preparation.