Efficient hot-electron transfer by a plasmon-induced interfacial charge-transfer transition

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Science  07 Aug 2015:
Vol. 349, Issue 6248, pp. 632-635
DOI: 10.1126/science.aac5443

Improving electron harvesting

Small metal nanostructures generate electrons from light by creating surface plasmons, which can transfer “hot electrons” to a semiconductor. The efficiency of this process, however, is often low because of electron-electron scattering. Wu et al. demonstrate a pathway that allows the plasmon to directly excite an electron in a strongly coupled semiconductor acceptor (see the Perspective by Kale). Cadmiun selenide nanorods bearing gold nanoparticles on their ends strongly damped plasmons via interfacial electron transfer with a quantum efficiency exceeding 24%.

Science, this issue p. 632; see also p. 587


Plasmon-induced hot-electron transfer from metal nanostructures is a potential new paradigm for solar energy conversion; however, the reported efficiencies of devices based on this concept are often low because of the loss of hot electrons via ultrafast electron-electron scattering. We propose a pathway, called the plasmon-induced interfacial charge-transfer transition (PICTT), that enables the decay of a plasmon by directly exciting an electron from the metal to a strongly coupled acceptor. We demonstrated this concept in cadmium selenide nanorods with gold tips, in which the gold plasmon was strongly damped by cadmium selenide through interfacial electron transfer. The quantum efficiency of the PICTT process was high (>24%), independent of excitation photon energy over a ~1–electron volt range, and dependent on the excitation polarization.

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