Plasmonic metal nanostructures (e.g. nanoparticles of Ag, Au, and Cu) have emerged as an important class of optically active materials because of their ability to interact strongly with visible light through the creation of surface plasmons. These collective electron oscillations can decay within the metal nanoparticles to form energetic charge carriers (i.e. electron-hole pairs). Recently, researchers have been asking whether it is possible to extract these charge carriers from photoexcited plasmonic nanoparticles to enable high efficiency solar energy conversion systems such as plasmon-enhanced photovoltaics or photocatalysis. Unfortunately, the fast thermalization of these charge carriers (~femtoseconds) within the plasmonic material greatly limits the efficiency of charge carrier extraction, and consequently the number of viable applications for plasmonic nanomaterials.
Herein, I discuss my work in the emerging field of hybrid plasmonics related to the extraction of photogenerated charge carriers from plasmonic nanostructures. I demonstrate that the extraction of charge carriers from plasmonic materials is attainable by interfacing them with non-plasmonic materials (e.g. semiconductors, molecules or metals). I use experimental and computational methods to reveal that the generation of charge carriers in the presence of a non-plasmonic material is governed by: (1) the intensity of the electric field generated by the plasmonic nanostructure, and (2) the availability of direct, electronic excitations in the non-plasmonic material. I then propose a unifying physical framework that leads us towards molecular control of charge carrier generation in all multicomponent plasmonic systems, which enables the design of highly efficient solar energy conversion technologies.
All seminars begin at 11:00 a.m. Eastern Daylight Time (UTC-04:00).