(135b) Factors Governing Charge Carrier Generation and Extraction in Hybrid Plasmonic Systems

Plasmonic metal nanostructures (e.g. nanoparticles of Ag, Au, and Cu) interact strongly with visible light through the creation of localized surface plasmons. The decay of these surface plasmons results in the formation of energetic charge carriers (electron-hole pairs) within the nanostructures, which can potentially be extracted to perform a function. Unfortunately, the extremely fast thermalization of these charge carriers (on the order of femtoseconds) within the plasmonic material greatly limits the efficiency of charge carrier extraction, and consequently the number of viable applications for plasmonic nanomaterials. In this contribution, we demonstrate that the efficient extraction of charge carriers from plasmonic materials is attainable by interfacing them with non-plasmonic materials (e.g. a semiconductor, molecule or another metal).^1-3 We use experimental and computational methods to study the rates of charge carrier generation in core–shell metal–metal, metal–semiconductor and metal–molecule systems. We reveal that the generation of energetic charge carriers in the presence of a non-plasmonic material is governed by two factors: (1) the intensity of the confined plasmon induced electric fields at the surface of the plasmonic nanostructure, and (2) the availability of direct, momentum conserved electronic excitations in the non-plasmonic material. We use these studies to propose a unifying physical framework that leads us towards molecular control of excited charge carrier generation in all hybrid plasmonic systems.

References

1. Aslam, U., Chavez, S. & Linic, S., Nature Nanotechnol. 12, 1000–1005 (2017).
2. Chavez, S., Aslam, U., & Linic, S., ACS Energy Letters. 3, 1590-1596 (2018).
3. Chavez, S., Govind Rao, V., & Linic, S., Faraday Discussions. 214, 441-453 (2019).