Observation of multi-directional energy transfer in a hybrid plasmonic-excitonic nanostructure

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Hybrid plasmonic devices involve a nanostructured metal supporting localized surface plasmons to amplify light–matter interaction, and a non-plasmonic material to functionalize charge excitations. Application-relevant epitaxial heterostructures, however, give rise to ballistic ultrafast dynamics that challenge the conventional semiclassical understanding of unidirectional nanometal-to-substrate energy transfer. Epitaxial Au nanoislands are studied on WSe2 with time- and angle-resolved photoemission spectroscopy and femtosecond electron diffraction: this combination of techniques resolves material, energy, and momentum of charge-carriers and phonons excited in the heterostructure. A strong non-linear plasmon–exciton interaction that transfers the energy of sub-bandgap photons very efficiently to the semiconductor is observed, leaving the metal cold until non-radiative exciton recombination heats the nanoparticles on hundreds of femtoseconds timescales. The results resolve a multi-directional energy exchange on timescales shorter than the electronic thermalization of the nanometal. Electron–phonon coupling and diffusive charge-transfer determine the subsequent energy flow. This complex dynamics opens perspectives for optoelectronic and photocatalytic applications, while providing a constraining experimental testbed for state-of-the-art modelling.


A combined study of electronic and lattice dynamics to observe multi-directional energy transfer in a hybrid plasmonic–excitonic nanostructure.


This work was funded by the Max Planck Society, the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation and the H2020-EU.1.2.1. FET Open programs (Grant Numbers: ERC-2015-CoG-682843, ERC-2015-AdG-694097, and OPTOlogic 899794), the Max Planck Society's Research Network BiGmax on Big-Data-Driven Materials-Science, and the German Research Foundation (DFG) within the Emmy Noether program (Grant Number: RE 3977/1), through SFB 951 “Hybrid Inorganic/Organic Systems for Opto-Electronics (HIOS)” (Project Number: 182087777, projects B12 and B17), the SFB/TRR 227 “Ultrafast Spin Dynamics” (projects A09 and B07), the Research Unit FOR 1700 “Atomic Wires” (project E5), and the Priority Program SPP 2244 (project 443366970). T. P. acknowledges financial support from the Alexander von Humboldt Foundation. T. V. acknowledges support from the Marie Skłodowska-Curie widening fellowship (101003436 - PLASMMONS). E. C. acknowledge the partial financial support from the National Science Centre (NCN) of Poland by the OPUS grant 2019/35/B/ST5/00248. S. B. acknowledges financial support from the NSERC-Banting Postdoctoral Fellowships Program. N. S. M. acknowledges support from the German National Academy of Sciences Leopoldina through the Leopoldina Postdoc Scholarship.


plasmons, excitons, ultrafast energy transfer, transition metal dichalcogenides


Advanced Materials, 35, Issue 9, 2209100, 2023


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Uniwersytet im. Adama Mickiewicza w Poznaniu
Biblioteka Uniwersytetu im. Adama Mickiewicza w Poznaniu
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