ChBE Seminar Series: Mark Swihart
Tuesday, October 16, 2007
11:00 a.m.-12:00 p.m.
Room 2110 Chemical & Nuclear Engineering Bldg.
Professor Sheryl Ehrman
Photoluminescent Silicon Nanocrystals: Aerosol Synthesis, Surface Functionalization and Applications Abstract
Presented by Mark Swihart
Department of Chemical and Biological Engineering
Photoluminescent silicon nanocrystals, or "quantum dots" (QDs) have great potential for use in applications ranging from low-cost flexible photovoltaics and light emitters to biological imaging and diagnostic applications, where they provide an attractive alternative to fluorescent organic dyes or potentially toxic heavy-metal-containing quantum dots. However, because of challenges related to the synthesis and surface modification of free-standing Si QDs, they have been much less studied than more easily prepared QDs of compound semiconductors such as CdSe. In all of their potential applications, stability and tunability of optical and electronic properties are important. In electronic device applications, transport of electrons and holes to and from the particles is also key. In biological systems, the QDs must remain stably dispersed in water and biological fluids, over a wide range of pH and salt concentration. Meeting these requirements requires engineering both the crystalline silicon core and its interface with the surroundings. This talk will outline our efforts in developing scalable, economical methods of preparing and modifying Si QDs for such applications. This includes high-rate laser driven aerosol synthesis, solution phase etching and surface modification, and encapsulation of surface-modified nanocrystals within phospholipid micelles for bioimaging.