Some New Developments in the Synthesis, Functionalization, and Utilization of Monodisperse Colloidal Spheres


  • This work was supported in part by the AFOSR, DARPA, NSF, ONR, and a Fellowship from the David and Lucile Packard Foundation. Y.X. is an Alfred P. Sloan Research Fellow and a Camille Dreyfus Teacher Scholar. U.J. was also partially supported by the postdoctoral fellowship program of the Korean Science and Engineering Foundation (KOSEF). M.I. thanks the Fulbright Foundation for a postdoctoral fellowship. Part of the work was performed at the Nanotech User Facility (NTUF), a member of the National Nanotechnology Infrastructure Network (NNIN) funded by the NSF.


This article provides an overview of some recent developments related to the synthesis and functionalization of monodisperse colloidal spheres, a class of colloidal materials that has found widespread use in applications such as the fabrication of photonic crystals, optical sensing, and drug delivery. Traditionally, the choice of materials has been limited to polystyrene and silica. We and other groups have recently expanded the scope of materials by developing a number of methods for producing monodisperse colloidal spheres from various semiconductors and metals. This article is confined to our own work; it covers three different synthetic strategies: the bottom–up approach, the top–down approach, and template-directed synthesis. The colloidal spheres may have a solid, hollow, or core–shell structure, and the chemical compositions can include Se, Bi, Pb, In, Sn, Cd, Pt, Ag2Se, CdSe, PbS, or TiO2. As an example to illustrate the attractive features of these colloidal spheres, we demonstrate the fabrication of Ag2Se-based photonic crystals whose stop bands can be thermally switched between two spectral positions.