Towards Solar Energy Storage in the Photochromic Dihydroazulene–Vinylheptafulvene System

Cacciarini, Martina; Skov, Anders B.; Jevric, Martyn; Hansen, Anne S.; Elm, Jonas; Kjaergaard, Henrik G.; Mikkelsen, Kurt V.; Nielsen, Mogens Brøndsted

doi:10.1002/chem.201500100

Cited by 93 publications

(99 citation statements)

References 29 publications

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“…In closing, we emphasize that the potential of using ESA as a photochemical design tool is heavily unexplored. Therefore, given the positive results reported in this minireview and the proven merits of computational modeling in studies of molecular photoswitches, it appears worthwhile for future research to investigate whether the ESA concept also can be employed to improve molecular photoswitches in other aspects than those discussed herein.…”

Section: Discussionmentioning

confidence: 99%

Molecular Photoswitching Aided by Excited‐State Aromaticity

2018

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Central to the development of optoelectronic devices is the availability of efficient synthetic molecular photoswitches, the design of which is an arena where the evolving concept of excited‐state aromaticity (ESA) is yet to make a big impact. The aim of this minireview is to illustrate the potential of this concept to become a key tool for the future design of photoswitches. The paper starts with a discussion of challenges facing the use of photoswitches for applications and continues with an account of how the ESA concept has progressed since its inception. Then, following some brief remarks on computational modeling of photoswitches and ESA, the paper describes two different approaches to improve the quantum yields and response times of switches driven by E/Z photoisomerization or photoinduced H‐atom/proton transfer reactions through simple ESA considerations. It is our hope that these approaches, verified by quantum chemical calculations and molecular dynamics simulations, will help stimulate the application of the ESA concept as a general tool for designing more efficient photoswitches and other functional molecules used in optoelectronic devices.

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Section: Discussionmentioning

confidence: 99%

Molecular Photoswitching Aided by Excited‐State Aromaticity

2018

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“…We were not able to perform reliable TS calculations in the junction in order to ascertain whether the kinetics of ring closure also agrees with experiment. Nevertheless, we have previously observed that the larger the dha − vhf energy difference, the faster is the vhf -to- dha conversion272829.…”

Section: Resultsmentioning

confidence: 97%

Single-molecule detection of dihydroazulene photo-thermal reaction using break junction technique

et al. 2017

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Charge transport by tunnelling is one of the most ubiquitous elementary processes in nature. Small structural changes in a molecular junction can lead to significant difference in the single-molecule electronic properties, offering a tremendous opportunity to examine a reaction on the single-molecule scale by monitoring the conductance changes. Here, we explore the potential of the single-molecule break junction technique in the detection of photo-thermal reaction processes of a photochromic dihydroazulene/vinylheptafulvene system. Statistical analysis of the break junction experiments provides a quantitative approach for probing the reaction kinetics and reversibility, including the occurrence of isomerization during the reaction. The product ratios observed when switching the system in the junction does not follow those observed in solution studies (both experiment and theory), suggesting that the junction environment was perturbing the process significantly. This study opens the possibility of using nano-structured environments like molecular junctions to tailor product ratios in chemical reactions.

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“…The basic physical effect responsible for this surprising feature is the delocalized nature of the polaritonic states obtained under collective strong coupling, which require a treatment of the whole collection of molecules as a single polaritonic supermolecule. For the specific model studied here, this strategy could resolve one of the main problems of solar energy storage; that is, how to efficiently retrieve the stored energy from molecules that are designed for the opposite purpose, i.e., for storing energy very efficiently under normal conditions [20,21]. By reversibly bringing the system into strong coupling (e.g., through a moving mirror that brings the cavity into and out of resonance), one could thus trigger the release of the stored energy through absorption of a single ambient photon.…”

Section: Prl 119 136001 (2017) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 99%

“…We thus investigate a class of reactions that release energy, i.e., where the initial starting state after absorption of a photon has higher energy than the final state, in which all involved molecules have undergone a reaction. We focus on a class of model molecules with a structure as proposed for use in solar energy storage [19][20][21], described within a simplified model treating a single reaction coordinate, as shown in Fig. 1(a).…”

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confidence: 99%

Inducing Multiple Reactions with a Single Photon

Ruggenthaler

2017

Physics

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The second law of photochemistry states that, in most cases, no more than one molecule is activated for an excited-state reaction for each photon absorbed by a collection of molecules. In this Letter, we demonstrate that it is possible to trigger a many-molecule reaction using only one photon by strongly coupling the molecular ensemble to a confined light mode. The collective nature of the resulting hybrid states of the system (the so-called polaritons) leads to the formation of a polaritonic "supermolecule" involving the degrees of freedom of all molecules, opening a reaction path on which all involved molecules undergo a chemical transformation. We theoretically investigate the system conditions for this effect to take place and be enhanced. DOI: 10.1103/PhysRevLett.119.136001 Photochemical reactions underlie many essential biological functions, such as vision or photosynthesis. In this context, the second law of photochemistry (also known as the Stark-Einstein law) states that "one quantum of light is absorbed per molecule of absorbing and reacting substance" [1]. This means that the quantum yield ϕ ¼ N prod =N phot of the reaction, which describes the percentage of molecules that end up in the desired reaction product per absorbed photon, has a maximum value of 1. This limit can be overcome in some specific cases, such as in photochemically induced chain reactions [2-4], or in systems that support singlet fission to create multiple triplet excitons (and thus electron-hole pairs) in solar cells [5,6].Polaritonic chemistry, i.e., the potential to manipulate chemical structure and reactions through the formation of polaritons (hybrid light-matter states) was experimentally demonstrated in 2012 [7], and has become a topic of intense experimental and theoretical research in the past few years [8][9][10][11][12][13][14][15][16][17][18]. However, existing applications and proposals have been limited to enhancing or suppressing the rates of single-molecule reactions. In this Letter we demonstrate a novel and general approach to circumvent the StarkEinstein law by exploiting the collective nature of polaritons formed by bringing a collection of molecules into strong coupling with a confined light mode. We show that this can allow many molecules to undergo a photochemical reaction after excitation by just a single photon. In contrast to conventional chain reactions, this polaritonic reaction does not rely on a near-resonant energy transfer condition between the excited stable and metastable ground state in the molecule. Our finding illustrates how polaritonic chemistry can open fundamentally new pathways that allow for reactions that are not present in the uncoupled system, and thus possesses the potential to unlock a new class of collective reactions.The mechanism we introduce relies on the delocalized character of the hybrid light-matter excitations (polaritons) formed under strong coupling (SC), which conceptually leads to the formation of a single "supermolecule" involving all the molecules as well as the trapp...

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Towards Solar Energy Storage in the Photochromic Dihydroazulene–Vinylheptafulvene System

Cited by 93 publications

References 29 publications

Molecular Photoswitching Aided by Excited‐State Aromaticity

Molecular Photoswitching Aided by Excited‐State Aromaticity

Single-molecule detection of dihydroazulene photo-thermal reaction using break junction technique

Inducing Multiple Reactions with a Single Photon

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