Research Article
Quantum coherence controls the charge separation in a prototypical artificial light-harvesting system
Carlo Andrea Rozzi, Sarah Maria Falke, Nicola Spallanzani, Angel Rubio, Elisa Molinari, Daniele Brida, Margherita Maiuri, Giulio Cerullo, Heiko Schramm, Jens Christoffers, Christoph Lienau
Published:
March 19, 2013
DOI:
10.1038/ncomms2603
License:
Copyright © 2013, Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.2013Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/
Abstract
The efficient conversion of light into electricity or chemical fuels is a fundamental challenge. In artificial photosynthetic and photovoltaic devices, this conversion is generally thought to happen on ultrafast, femto-to-picosecond timescales and to involve an incoherent electron transfer process. In some biological systems, however, there is growing evidence that the coherent motion of electronic wavepackets is an essential primary step, raising questions about the role of quantum coherence in artificial devices. Here we investigate the primary charge-transfer process in a supramolecular triad, a prototypical artificial reaction centre. Combining high time-resolution femtosecond spectroscopy and time-dependent density functional theory, we provide compelling evidence that the driving mechanism of the photoinduced current generation cycle is a correlated wavelike motion of electrons and nuclei on a timescale of few tens of femtoseconds. We highlight the fundamental role of the interface between chromophore and charge acceptor in triggering the coherent wavelike electron-hole splitting. In artificial photosynthetic devices, conversion of light into electricity is thought to involve an incoherent electron transfer process. Rozzi et al. provide evidence for quantum-correlated wavelike motion inducing the ultrafast photoinduced electronic charge transfer in a light-harvesting supramolecular triad.