(Invited) Plasmon Induced Hot Electron Transfer from Doped Semiconductor Nanocrystals

Abstract

In recent years, a new class of plasmonic materials based on doped semiconductor NCs has been developed. Similar to noble metals, localized surface plasmon resonances in doped semiconductor NCs arises from the coherent collective oscillation of free carriers within the NCs. The wide tunability of free carrier concentration results in tunable plasmon bands spanning from the visible to mid-infrared regime and these plasmonic semiconductor NCs have been reported to drive plasmonic hot carrier photocatalysis under near IR light illumination. These reports suggest that plasmonic semiconductors is an interesting material platform for efficient near IR driven hot carrier photocatalysis. So far the reported efficiencies are low and the mechanisms of hot carrier generation, transfer and recombination are unclear. There are interesting similarities and differences between metal and semiconductor plasmonics. First, plasmons in semiconductors can decay by inter- (band gap) and intra- band plasmon decay. Furthermore, charge transfer transition in semiconductor heterostructures have been extensively reported; can plasmon decay in plasmonic-semiconductor/semiconductor junctions proceed by exciting interfacial ET across the junction, similar to the PICTT pathway reported for metal/semiconductor junctions? Second, in plasmonic semiconductor materials, where there is a lack of states within the p-semiconductor bandgap, the transferred electrons in the accepting semiconductor CB can recombine only with the VB holes in the plasmonic semiconductor. This process requires dissipation of ~ >1 eV energy, which may slow down the recombination rate. In this talk, I will discuss our recent progresses in studying plasmon induced hot electron transfer and recombination in plasmonic semiconductor/semiconductor interfaces.