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EP02.04.15 : Plasmon Induced Energy Transfer Revealed by Means of the Sampled-Transmitted Photoluminescence Spectroscopy

5:00 PM–7:00 PM Apr 3, 2018 (America - Denver)

PCC North, 300 Level, Exhibit Hall C-E

Description
Dmitry Porotnikov1 Mikhail Zamkov1

1, Bowling Green State University, Bowling Green, Ohio, United States

The superior optical extinction characteristics of noble metal nanoparticles have long been considered for enhancing the solar energy absorption in light-harvesting devices. The energy captured through a plasmon resonance mechanism can potentially be transferred to a surrounding semiconductor matrix in form of excitons or charge carriers offering a promising light-sensitization strategy. Of a particular interest is the plasmon near-field energy conversion, which is predicted to yield substantial gains in the photocarrier generation. Such short-range interaction, however, is often inhibited by processes of backward electron and energy transfer, which obscure its net benefit. Here, we employ the sample-transmitted excitation photoluminescence (STEP) spectroscopy to determine the quantum efficiency for the plasmon induced energy transfer (ET) in assemblies of Au nanoparticles and CdSe nanocrystals. The present technique distinguishes the Au-to-CdSe ET contribution from metal-induced quenching processes thus enabling accurate estimates of the photon-to-exciton conversion efficiency. We show that in the case of 9.1-nm Au nanoparticles, only 1-2% of the Au absorbed radiation is converted to excitons in the surrounding CdSe nanocrystal matrix. For larger, 21.0-nm Au, the photon-to-exciton conversion efficiency increases to 29.5%. The results of present measurements were used to develop an empirical model for estimating the maximum gain in plasmon-induced carriers versus the mass-fraction of Au in a film.

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