Measures and implications of electronic coherence in photosynthetic light-harvesting

Smyth, Cathal; Fassioli, Francesca; Scholes, Gregory D.

doi:10.1098/rsta.2011.0420

Cited by 47 publications

(61 citation statements)

References 79 publications

(177 reference statements)

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“…A first attempt has been to quantify electronic coherence through metrics derived in the context of quantum information science [12]. In this Meeting Issue, the article by Smyth et al [13] compares different measures of exciton delocalization. This subject is critically assessed in the article by Tiersch et al [14], concluding that further research is needed to identify figures of merit that unambiguously show the advantages of quantum behaviour.…”

Section: (C) Characterization Of Quantum Features Relevant For Excitamentioning

confidence: 99%

Quantum-coherent energy transfer: implications for biology and new energy technologies

Olaya-Castro

Nazir

Fleming

2012

Phil. Trans. R. Soc. A.

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Section: (C) Characterization Of Quantum Features Relevant For Excitamentioning

confidence: 99%

Quantum-coherent energy transfer: implications for biology and new energy technologies

Olaya-Castro

Nazir

Fleming

2012

Phil. Trans. R. Soc. A.

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“…In a less general setting, one can establish a direct connection between quantum coherence and other physical properties, such as delocalization or entanglement [166]. In a number of photosynthetic light-harvesting complexes, for example, the system of interest is formed by a number of well-defined subsystems (chromophores), which provide a local basis for the description of the electronic excitations.…”

Section: Quantum Coherence and Delocalizationmentioning

confidence: 99%

“…More specifically, entanglement-based quantifiers of coherence have been defined, based on the intuition that quantum coherence in a given system S 1 is required in order to generate entanglement between S 1 and a second system S 2 through incoherent operations [171]. In a less general framework, one can derive direct relations between coherence and entanglement quantifiers or witnesses [161,166]. In particular, we consider the above mentioned single-excitation manifold, spanned by the states |i , each one corresponding to the excitation being localized in the i-th two-level subsystem.…”

Section: Quantum Coherence and Entanglementmentioning

confidence: 99%

“…The above relation does not depend on the specific definition of the subsystems i, provided that the above mentioned structure of the Hilbert space is preserved, as well as the constraint on the overall number of excitations. Analogous relations between purity, entanglement and IPR can be derived [166] 8 Theoretical spectroscopies…”

Section: Quantum Coherence and Entanglementmentioning

confidence: 99%

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Quantum modeling of ultrafast photoinduced charge separation

Rozzi

Troiani

Tavernelli

2017

J. Phys.: Condens. Matter

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Phenomena involving electron transfer are ubiquitous in nature, photosynthesis and enzymes or protein activity being prominent examples. Their deep understanding thus represents a mandatory scientific goal. Moreover, controlling the separation of photogenerated charges is a crucial prerequisite in many applicative contexts, including quantum electronics, photo-electrochemical water splitting, photocatalytic dye degradation, and energy conversion. In particular, photoinduced charge separation is the pivotal step driving the storage of sun light into electrical or chemical energy. If properly mastered, these processes may also allow us to achieve a better command of information storage at the nanoscale, as required for the development of molecular electronics, optical switching, or quantum technologies, amongst others.In this Topical review we survey recent progress in the understanding of ultrafast charge separation from photoexcited states. We report the state-of-the-art of the observation and theoretical description of charge separation phenomena in the ultrafast regime mainly focusing on molecularand nano-sized solar energy conversion systems. In particular, we examine different proposed mechanisms driving ultrafast charge dynamics, with particular regard to the role of quantum coherence and electron-nuclear coupling, and link experimental observations to theoretical approaches based either on model Hamiltonians or on first principles simulations.

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“…In particular, we calculate the inverse participation ratio [41] and find that the bright states are consistently more delocalized than the dark states, independent of the oligomer displacement (see Supplementary Information). This behavior also persists in more structurally complicated models.…”

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confidence: 99%

Optical Spectra of p-Doped PEDOT Nanoaggregates Provide Insight into the Material Disorder

et al. 2016

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Highly doped Poly (3,4-ethylenedioxythiophene) or PEDOT is a conductive polymer with a wide range of applications in energy conversion due to its ease of processing, optical properties and high conductivity. The latter is influenced by processing conditions, including formulation, annealing, and solvent treatment of the polymer, which also affects the polymer arrangement. Here we show that the analysis of the optical spectra of PEDOT domains reveals the nature and magnitude of the structural disorder in the material. In particular, the optical spectra of objects on individual domains can be used for the elucidation of the molecular disorder in oligomer arrangement which is a key factor affecting the conductivity. their conventional inorganic counterparts in a number of energy related applications [1], including photovoltaics [2,3], fuel cells [4,5] and low-cost and environmentally-safe thermoelectrics [6][7][8][9].A central feature of many of these devices is a transparent, flexible conductor layer. Among several materials employed for this layer, materials based on poly(3,4-ethylenedioxythiophene) (PEDOT) stand out due to their high hole conductivity, chemical stability, and transparency to visible light [10]. PEDOT-based structures have been incorporated in touch screens, light-emitting diodes, and photovoltaic elements, to mention a few examples [11]. Though multiple experimental investigations have addressed the molecular organization of PEDOT-based materials, the microscopic electronic states that lead to high conductance and the interplay between these states, optical properties, and the material structure has yet to be definitively characterized. The main obstacle to elucidating this relationship is the strong structural disorder that appears on multiple length scales and is highly sensitive to the preparation procedure [10].In this work, we link the supramolecular packing of PEDOT with its optical absorption spectra. We argue that optical spectroscopy of PEDOT aggregates on a single domain level can be used for characterization of the microscopic electronic structure in the material that is a function of molecular disorder. Specifically, we show how disorder in two packing models, widely accepted for PEDOT aggregates, leads to a transition between J-and H-aggregation [12,13] reflected in optical spectra. Finally, we identify the degree of disorder potentially responsible for this transition and study the changes in localization of the bright and dark states, in order to better understand the character of the spectral peaks. As we show below, disorder tends to localized the states and bright states are more delocalized than the dark ones. As a model system, we focus on structures composed of multiply charged oligomers. This model matches the experimentally determined charge density in highly conducting PEDOT.A high-conductance regime is observed for p-doped PEDOT [16] when the injection of positive charges induces a structural relaxation effectively forming polaron and bipolaron states [17]. In this case...

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Measures and implications of electronic coherence in photosynthetic light-harvesting

Cited by 47 publications

References 79 publications

Quantum-coherent energy transfer: implications for biology and new energy technologies

Quantum-coherent energy transfer: implications for biology and new energy technologies

Quantum modeling of ultrafast photoinduced charge separation

Optical Spectra of p-Doped PEDOT Nanoaggregates Provide Insight into the Material Disorder

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