Dark states enhance the photocell power via phononic dissipation

Zhang, Yiteng; Wirthwein, Aaron; Alharbi, Fahhad H.; Engel, Gregory S.; Kais, Sabre

doi:10.1039/c6cp06098f

Cited by 14 publications

(14 citation statements)

References 24 publications

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“…To calculate the steady state dynamics of the combined antenna-trap system, we follow the procedures used in Ref. 14,15 by setting up a standard Lindblad optical master equation: Table 1 with the physical meaning of each parameter described in the leftmost panel. For the detailed equation forms where these parameters appear in equation (4) (4) is obtained using the open-source quantum dynamics software QuTiP 16 .…”

Section: IImentioning

confidence: 99%

“…On the other hand, the formation of the collective eigenstates delocalizes the excitation away from the trapping site, and may reduce the energy transfer efficiency. Therefore, a competition between dark state protection and delocalization needs to be considered when optimizing the size of light harvesting systems 15 . Here, we examine these two competing mechanisms in detail for an antenna composed of a chain of varied numbers of chromophore subunits.…”

Section: Introductionmentioning

confidence: 99%

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Dark states and delocalization: Competing effects of quantum coherence on the efficiency of light harvesting systems

Engel

Alharbi

et al. 2018

The Journal of Chemical Physics

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Natural light harvesting systems exploit electronic coupling of identical chromophores to generate efficient and robust excitation transfer and conversion. Dark states created by strong coupling between chromophores in the antenna structure can significantly reduce radiative recombination and enhance energy conversion efficiency. Increasing the number of the chromophores increases the number of dark states and the associated enhanced energy conversion efficiency yet also delocalizes excitations away from the trapping center and reduces the energy conversion rate. Therefore, a competition between dark state protection and delocalization must be considered when designing the optimal size of a light harvesting system. In this study, we explore the two competing mechanisms in a chain-structured antenna and show that dark state protection is the dominant mechanism, with an intriguing dependence on the parity of the number of chromophores. This dependence is linked to the exciton distribution among eigenstates, which is strongly affected by the coupling strength between chromophores and the temperature. Combining these findings, we propose that increasing the coupling strength between the chromophores can significantly increase the power output of the light harvesting system.

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Section: IImentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dark states and delocalization: Competing effects of quantum coherence on the efficiency of light harvesting systems

Engel

Alharbi

et al. 2018

The Journal of Chemical Physics

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“…Modeling has shown that careful optimization of the coupling of the monomers, through tuning their optical properties and relative position and orientation, leads to a hybridization and energy splitting of the single exciton eigenstates. The lower of these states can be optically inactive-the so-called dark state [5,6,10,11], whereas the higher lying state has an enhanced transition dipole-this is the bright state. The dark state is accessed by non-radiative, vibrational relaxation from the bright state.…”

Section: Introductionmentioning

confidence: 99%

Optimal power generation using dark states in dimers strongly coupled to their environment

2019

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Dark state protection has been proposed as a mechanism to increase the power output of light harvesting devices by reducing the rate of radiative recombination. Indeed many theoretical studies have reported increased power outputs in dimer systems which use quantum interference to generate dark states. These models have typically been restricted to particular geometries and to weakly coupled vibrational baths. Here we consider the experimentally-relevant strong vibrational coupling regime with no geometric restrictions on the dimer. We analyze how dark states can be formed in the dimer by numerically minimizing the emission rate of the lowest energy excited eigenstate, and then calculate the power output of the molecules with these dark states. We find that there are two distinct types of dark states depending on whether the monomers form homodimers, where energy splittings and dipole strengths are identical, or heterodimers, where there is some difference. Homodimers, which exploit destructive quantum interference, produce high power outputs but strong phonon couplings and perturbations from ideal geometries are extremely detrimental. Heterodimers, which are closer to the classical picture of a distinct donor and acceptor molecule, produce an intermediate power output that is relatively stable to these changes. The strong vibrational couplings typically found in organic molecules will suppress destructive interference and thus favor the dark-state enhancement offered by heterodimers.

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“…through interference in multi-level systems [6,7] or as dark-state protection with multiple interacting dipoles [8][9][10][11]. Optical ratcheting [12,13] may offer further advantages by allowing an antenna to keep absorbing whilst being immune to recombination. Recent work underlines the importance of expanding beyond the single excitation subspace even in the presence of excitonexciton annihilation [12,14].…”

Section: Introduction -Photosynthesis Powers Most Life Onmentioning

confidence: 99%

Light Harvesting with Guide-Slide Superabsorbing Condensed-Matter Nanostructures

Brown

Gauger

2019

J. Phys. Chem. Lett.

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We establish design principles for light-harvesting antennae whose energy capture scales superlinearly with system size. Controlling the absorber dipole orientations produces sets of 'guide-slide' states which promote steady-state superabsorbing characteristics in noisy condensed-matter nanostructures. Inspired by natural photosynthetic complexes, we discuss the example of ring-like dipole arrangements and show that, in our setup, vibrational relaxation enhances rather than impedes performance. Remarkably, the superabsorption effect proves robust to O(5%) disorder simultaneously for all relevant system parameters, showing promise for experimental exploration across a broad range of platforms.

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Dark states enhance the photocell power via phononic dissipation

Cited by 14 publications

References 24 publications

Dark states and delocalization: Competing effects of quantum coherence on the efficiency of light harvesting systems

Dark states and delocalization: Competing effects of quantum coherence on the efficiency of light harvesting systems

Optimal power generation using dark states in dimers strongly coupled to their environment

Light Harvesting with Guide-Slide Superabsorbing Condensed-Matter Nanostructures

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