Intramolecular radiationless transitions dominate exciton relaxation dynamics

Jumper, Chanelle C.; Anna, Jessica M.; Stradomska, Anna; Schins, Juleon M.; Myahkostupov, Mykhaylo; Prusakova, Valentina; Oblinsky, Daniel G.; Castellano, Felix N.; Knoester, Jasper; Scholes, Gregory D.

doi:10.1016/j.cplett.2014.03.007

Cited by 41 publications

(67 citation statements)

References 125 publications

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“…156 In addition to the pronounced blue-shift of the absorption spectra, the fluorescence quantum yields were drastically reduced for the H-coupled PBI dimers 2-3 and 2-4a, whereas dimers 2-4b,c showed higher values. 155,156 In contrast to the PBI dimers discussed in the previous section, the covalent PBI ensembles shown in Chart 2 enforce considerable π−π-interactions as the constituent chromophores are in close vicinity to each other with predefined alignments imposed by the respective rigid backbones. In the atropoenantiomeric PBI dimers 2-5a and 2-5b (one enantiomer of each is shown) with axially chiral biphenylene (2-5a) 157 or binaphthylene (2-5b) 158 tether, the chromophore units are aligned in an almost perpendicular fashion as revealed by quantum chemical calculations.…”

Section: Rigid Pbi Dimersmentioning

confidence: 95%

Perylene Bisimide Dye Assemblies as Archetype Functional Supramolecular Materials

et al. 2015

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CONTENTS 1. Introduction 962 1.1. Prologue 962 1.2. Parent Perylene Bisimide Chromophore 963 1.3. Core-Substituted Perylene Bisimides 964 1.4. Perylene Bisimides in the Solid State 966 1.5. Areas of Application 966 2. Linear, Dendritic, and Macrocyclic Covalent PBI Ensembles 968 2.1. Excitonic Coupling and Deactivation Processes of Photoexcited PBIs 969 2.2. Rigid PBI Dimers 971 2.3. Flexible PBI Ensembles 974 2.4. Cyclic PBI Ensembles 976 3. π-Stacked PBI Assemblies 979 3.1. Self-Assembly of Core-Unsubstituted PBIs in Solution 979 3.2. Organization of Core-Unsubstituted PBIs in the Bulk Solid State 984 3.3. Self-Assembly of Amphiphilic PBIs in Aqueous Media and Solid Bulk State 987 3.4. Self-Assembly of Core-Substituted PBIs 991 3.5. Self-Assembly of Dye Arrays Composed of Multiple PBIs 995 3.6. Self-Assembly of Multichromophoric PBI Conjugates Containing Other Dyes 996 4. Hydrogen-Bond Directed Self-Assembly 1000 4.1. Self-Assembly Directed by Imide−Imide H-Bonding Interactions 1000 4.2. Self-Assembly Directed by Side-Chain Amide−Amide H-Bonding Interactions 1003 4.3. Self-Assembly Directed by Other H-Bonding Interactions 1006 4.4. Coassembly Directed by Imide−Melamine H-Bonding Interactions 1008 4.5. Coassembly Directed by Melamine−Cyanurate/Barbiturate H-Bonding Interactions 1011

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Section: Rigid Pbi Dimersmentioning

confidence: 95%

Perylene Bisimide Dye Assemblies as Archetype Functional Supramolecular Materials

et al. 2015

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“…The vibrational motions of molecules, however, play interesting roles in the subsequent dynamical evolution. For example, ultrafast relaxation of the higher-energy exciton to the lowest molecular exciton by radiationless transitions can diphase the exciton superposition 40 . In contrast, vibrations are implicated in sustaining coherence [14][15][16] .…”

Section: Discussionmentioning

confidence: 99%

Room-temperature exciton coherence and dephasing in two-dimensional nanostructures

et al. 2015

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Electronic coherence has attracted considerable attention for its possible role in dynamical processes in molecular systems. However, its detection is challenged by inhomogeneous line broadening and interference with vibrational coherences. In particular, reports of 'persistent' coherent exciton superpositions at room temperature remain controversial, as the related transitions give typically shorter optical dephasing times of about 10-20 fs. To rationalize these reported long-lived coherences, several models have been proposed, involving strong correlation in the mechanisms of decoherence or that electronic coherences may be sustained by resonant vibrational modes. Here we report a decisive example of electronic coherence occurring in a chemical system in a 'warm and wet' (room-temperature solution) environment, colloidal semiconductor nanoplatelets, where details are not obscured by vibrational coherences nor ensemble dephasing. Comparing the exciton and optical coherence times evidences a partial correlation of fluctuations underlying dephasing and allows us to elucidate decoherence mechanisms occurring in these samples.

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“…15,16 In multichromophoric assemblies such as those formed by self-assembly of π-conjugated molecular dyes, even a minimal change of the structural parameters can significantly change the efficiency of nonradiative relaxation processes. The coupling between the chromophores in such superstructures can give rise to novel funnels between the delocalized exciton-or charge transfer states that enhance the nonradiative relaxation and limit their functionality, similar to the well established role which conical intersections play in molecular photochemistry.…”

Section: Introductionmentioning

confidence: 99%

The mechanism of excimer formation: an experimental and theoretical study on the pyrene dimer

Hoche

Schmitt

Humeniuk

et al. 2017

Phys. Chem. Chem. Phys.

126

125

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a These authors contributed equally to the work. AbstractThe understanding of excimer formation in organic materials is of fundamental importance, since it profoundly influences their functional performance in applications such as light-harvesting, photovoltaics or organic electronics. We present a joint experimental and theoretical study of the ultrafast dynamics of excimer formation in the pyrene dimer, which is the archetype of an excimer forming system. We perform simulations of the nonadiabatic photodynamics in the frame of TDDFT that reveal two distinct excimer formation pathways in the gas-phase dimer. The first pathway involves local excited state relaxation close to the initial Frank-Condon geometry that is characterized by a strong excitation of the stacking coordinate exhibiting damped oscillations with a period of 350 fs that persist for at least 5 ps. The second excimer forming pathway involves large amplitude oscillations along the parallel shift 1 coordinate with a period of ≈ 900 fs that after intramolecular vibrational energy redistribution on a 2 ps time scale leads to the formation of a perfectly stacked dimer.The electronic relaxation within the excitonic manifold is mediated by the presence of conical intersections formed between fully delocalized excitonic states. Such conical intersections may generally arise in stacked π-conjugated aggregates due to the interplay between the long-range and short-range electronic coupling. The simulations are supported by picosecond photoionization experiments in a supersonic jet that provide a time-constant for the excimer formation of around 6-8 ps, in excellent agreement with theory. Finally, in order to explore how the crystal environment influences the excimer formation dynamics we perform large scale QM/MM nonadiabatic dynamics simulations on a pyrene crystal in the framework of the tight-binding TDDFT. In contrast to the isolated dimer, the excimer formation in the crystal follows a single reaction pathway in which the initially excited parallel slip motion is strongly damped by collisions with the surrounding molecules leading to the slow excimer stabilization with a time constant of several picoseconds.2

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Intramolecular radiationless transitions dominate exciton relaxation dynamics

Cited by 41 publications

References 125 publications

Perylene Bisimide Dye Assemblies as Archetype Functional Supramolecular Materials

Perylene Bisimide Dye Assemblies as Archetype Functional Supramolecular Materials

Room-temperature exciton coherence and dephasing in two-dimensional nanostructures

The mechanism of excimer formation: an experimental and theoretical study on the pyrene dimer

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