Comparison of different rate constant expressions for the prediction of charge and energy transport in oligoacenes

Stehr, Vera; Fink, Reinhold F.; Tafipolski, Maxim; Deibel, Carsten; Engels, Bernd

doi:10.1002/wcms.1273

Cited by 55 publications

(73 citation statements)

References 161 publications

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“…The rate of electron transfer is described in the framework of the Fermi's Golden Rule; assuming the Franck-Condon www.advmatinterfaces.de approximation and the high-temperature regime (when the vibrational modes can be treated classically), the charge-transfer rate is given by the semiclassical Marcus expression [34][35][36][37][38] …”

Section: Charge-transfer Parametersmentioning

confidence: 99%

Structure and Charge Transport Properties of Cycloparaphenylene Monolayers on Graphite

Pérez-Guardiola

Pérez-Jiménez

Muccioli³

et al. 2019

Adv Materials Inter

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The synthesis of CPPs has been experimentally challenging due to the strain energy needed to close the ring. [7] Vögtle and co-workers [8,9] attempted to synthesize CPPs from macrocycles formed by arene and cyclohexane units to therefore reduce the strain energy of the system. However, the first synthesis of CPPs was afforded only by Jasti et al. [10] in 2008, followed by the first selective synthesis of CPPs by Itami and co-workers [11,12] using a modular approach to build [n]CPPs with n ⩾ 12. Other successfully strategies (Yamago et al. [13] ) use a square-shaped tetra platinum biphenyl complex as an intermediate to selectively synthesize the [8]CPP molecule. In the above mentioned works, it was possible to obtain CPPs in the milligram-scale, with Jasti and co-workers [6,14] producing the first gram-scale synthesis. The smallest CPP synthesized up to date is [5]CPP, [15] which shows the great success achieved so far in overcoming the strain energy.Concerning the supramolecular packing, the solid-state (3D) structure of CPPs has been characterized in several works by means of X-ray diffraction. [16,17] The molecules self-assemble in a herringbone (HB) pattern independently of their size, as it often happens for other π-conjugated systems. An exception is the [6]CPP case, for which three different polymorphs have been found up to date. The first solid-state characterization of [6]CPP revealed a tubular-like structure, [14] but a recent study revealed that the crystallographic structure might depend on the crystallization conditions, also finding a herringbone configuration a few kcal mol −1 more stable than the tubular one. [18] More recently, another polymorph of [6]CPP has been found when the crystallization is carried out by sublimation at 220 °C. In these conditions, no solvent molecules are occluded inside the [6]CPP cavity, and thus, a concave-convex structure appears (i.e., molecules tightly packed in a T-like shape minimizing the internal space inside the cavities). [19] These findings clearly reveal the subtle yet dominant effect of the weak intermolecular interactions driving the supra molecular self-assembly of these systems. Motivated by this, some of us investigated in a previous theoretical work the adsorption energies of [8]CPP on small carbon nanoflakes (circumcirmcumcoronene) and how these through-space weak forces can serve to immobilize the systems in energetically favored configuration. [20] In the present study, we wish to go a step further and employ a tailored force field and molecular dynamics (MD) simulations to predict the supramolecular structure of thin films of CPPs on graphite surfaces. The systematic exploration of the adsorption The nanoscale organization of cycloparaphenylene molecules when physisorbed on a graphite surface is theoretically investigated by means of atomistic molecular dynamics simulations employing a tailored and benchmarked force field. The landing of a single molecule is first considered, to progressively deposit more molecules to finally reach the full coverage...

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Section: Charge-transfer Parametersmentioning

confidence: 99%

Structure and Charge Transport Properties of Cycloparaphenylene Monolayers on Graphite

Pérez-Guardiola

Pérez-Jiménez

Muccioli³

et al. 2019

Adv Materials Inter

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“…Employing a monomer hopping model in combination with the Marcus approach, predicts an L D value of 160 nm for a-PTCDA, which is almost an order of magnitude too large, while a reasonable value of 100 nm was computed for DIP. 100,101 This indicates that the monomer-based model misses some important effects for a-PTCDA which seem to be less important or not active in DIP crystals. Simple disorder effects, which are expected to limit the L D for amorphous systems, should be less significant because both measurements were performed on single crystals.…”

Section: Exciton Diffusion Lengths: A-ptcda Versus Dipmentioning

confidence: 99%

“…Consequently, a monomer based hopping model which neglects such trapping effects but carefully considers relevant intra-monomer motions can provide reasonable L D values. 100,101 Our examples given for the three perylene based aggregates PBI, PTCDA and DIP show that the dimer approach is necessary if fast trapping effects are important which involve relaxation pathways along inter-monomer coordinates leading to a population transfer to a lower lying state. Efficient trapping does not occur if the relaxation takes place in a single state because the corresponding PESs are very flat.…”

Section: Exciton Diffusion Lengths: A-ptcda Versus Dipmentioning

confidence: 99%

The dimer-approach to characterize opto-electronic properties of and exciton trapping and diffusion in organic semiconductor aggregates and crystals

Engels

Engel

2017

Phys. Chem. Chem. Phys.

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A fundamental understanding of photo-induced processes in opto-electronic thin film devices is a prerequisite for the rational design of improved organic semiconductor materials. Absorption and emission spectra provide important insights into the complicated electronic structure of and relaxation processes in organic semiconductor aggregates and crystals. They are of interest because they often limit the efficiencies of the devices. For an assignment of the spectra a close interplay between experiment and theory is essential because simulations are often necessary to entangle the various effects which determine the features of the spectra. In the present perspective we describe the so called dimer-approach and provide a few examples in which this approach could successfully deliver an atomistic picture of photo-induced relaxation effects in perylene-based materials and characterize their optical spectra. The model Hamiltonians of standard monomer-based approaches are also briefly discussed to reveal the differences between both methods and to shed some light on their strengths and shortcomings.

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“…In the MLJ formalism, a single effective mode with an energy ℏω eff , which represents all the intramolecular modes, is treated at the quantummechanical level via the effective Huang-Rhys factor S eff = λ i /ℏω eff (ℏω eff was set here equal to 0.2 eV, which is the typical energy of C-C stretching modes). [39][40][41] On the contrary, the intermolecular modes are treated classically through the λ s parameter. In organic crystals, the outer reorganization energy is in the order of few tenths of an electronvolt or lower, contrary to charge transfer in solution wherein the external part dominates.…”

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confidence: 99%

Optoelectronic and Semiconducting Properties of Conjugated Polymers Composed of Thiazolo[5,4-d]thiazole and Arene Imides Linked by Ethynylene Bridges

et al. 2016

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A set of engineered crystalline polymers containing thiazolo [5,4-d]thiazole and arene imides linked by ethynylene bridges have been modelled by means of Density Functional Theory (periodic boundary) calculations. A large set of relevant electronic properties related to the opto-electronic and semiconductor character of these systems, such as optical band gap, frontier molecular orbital energy levels, electron affinity, ionization potential, reorganization energy, and electronic coupling between neighboring polymer chains were obtained. We further discuss the effect of the ethynylene linkages, the presence of heteroatoms in thiazolo [5,4-d]thiazole rings, and

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Comparison of different rate constant expressions for the prediction of charge and energy transport in oligoacenes

Cited by 55 publications

References 161 publications

Structure and Charge Transport Properties of Cycloparaphenylene Monolayers on Graphite

Structure and Charge Transport Properties of Cycloparaphenylene Monolayers on Graphite

The dimer-approach to characterize opto-electronic properties of and exciton trapping and diffusion in organic semiconductor aggregates and crystals

Optoelectronic and Semiconducting Properties of Conjugated Polymers Composed of Thiazolo[5,4-d]thiazole and Arene Imides Linked by Ethynylene Bridges

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