Luminescence quenching of ordered π-conjugated molecules near a metal surface: Quaterthiophene and PTCDA on Ag(111)

Gebauer, W.; Langner, Andreas; Schneider, Michael; Sokołowski, M.; Umbach, E.

doi:10.1103/physrevb.69.155431

Cited by 66 publications

(82 citation statements)

References 30 publications

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“…Such molecules pack in a herringbone arrangement with at least 2 molecules in a unit cell. [20][21][22][23] Here, the lower Davydov component ͑alias J-band͒ is weakly allowed along the crystal b direction, 20,[24][25][26] leading to b-polarized superradiant 0-0 emission 27 which diminishes with increasing disorder. [28][29][30][31] In helical MOPVn aggregates, coherence affects the PL spectrum in a manner similar to the ideal linear H-aggregates described above.…”

Section: Introductionmentioning

confidence: 99%

Using circularly polarized luminescence to probe exciton coherence in disordered helical aggregates

Spano

Meskers

Hennebicq

et al. 2008

The Journal of Chemical Physics

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Circularly polarized emission from helical MOPV4 aggregates is studied theoretically based on a Hamiltonian including excitonic coupling, exciton phonon coupling, and site disorder. The latter is modeled via a Gaussian distribution of site energies. The frequency dependence of the circularly polarized luminescence dissymmetry g lum ͑͒ contains structural information about the low-energy-neutral ͑excitonic͒ polaron from which emission originates. Near the 0-0 emission frequency, g lum ͑͒ provides a measure of the exciton coherence length, while at lower energies, in the vicinity of the sideband frequencies, g lum ͑͒ probes the polaron radius. The present work focuses on how the 0-0 dissymmetry, g lum 0-0 , relates to the emitting exciton's coherence function, from which the coherence length is deduced. In the strong disorder limit where the exciton is localized on a single chromophore, g lum 0-0 is zero. As disorder is reduced and the coherence function expands, ͉g lum 0-0 ͉ increases more rapidly than the sideband dissymmetries, resulting in a pronounced surge in g lum ͑͒ near the 0-0 transition frequency. The resulting spectral shape of g lum ͑͒ is in excellent agreement with recent experiments on MOPV4 aggregates. In the limit of very weak disorder, corresponding to the motional narrowing regime, the coherence function extends over the entire helix. In this region, g lum 0-0 undergoes a surprising sign reversal but only for helices which are between n + 1 2 and n + 1 complete turns ͑n =0,1, ...͒. This unusual sign change is due to the dependence of the rotational line strength on long-range exciton coherences which are also responsible for a heightened sensitivity of g lum ͑͒ to long-range excitonic coupling.

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Section: Introductionmentioning

confidence: 99%

Using circularly polarized luminescence to probe exciton coherence in disordered helical aggregates

Spano

Meskers

Hennebicq

et al. 2008

The Journal of Chemical Physics

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“…Further, it is well known that the optical properties of organic materials depend strongly on the packing of the molecules. [8] Highly ordered thin films as grown by organic molecular beam epitaxy [9][10][11] (OMBE) are especially suitable to study interface effects [12,13] due to the well-defined physical structure and accurate thickness control. Here, we compare the optical absorbance behavior of ultrathin films made of the polycyclic aromatic hydrocarbon quaterrylene (QT, C 40 H 20 , Fig.…”

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confidence: 99%

Electronic Decoupling of Aromatic Molecules from a Metal by an Atomically Thin Organic Spacer

et al. 2008

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Electronic coupling effects of organic adsorbates to metallic surfaces are examined optically. Covering a Au(111) substrate with an ultrathin (∼0.3 nm) nanographene‐like layer of flat lying molecules leads to decoupling of further molecular layers to a large extent. Our work suggests that not only inorganic salts or oxides can be used as insulating spacers but also particular organic monolayers.

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“…Its herringbone structure and quasi-epitaxial growth on various substrates have been characterized at length and allow for controlled layer deposition [13,14,15]. The electronic structure of PTCDA has been studied in the bulk phase and at several interfaces [16,17,18,19], and measurements of charge transport properties are reported in the literature [20]. Several recent studies have examined interfacial states of PTCDA specific to the Ag(111) surface that are hybrid states of PTCDA bulk electronic states mixing with the Ag 5sp band [21,22].…”

Section: Introductionmentioning

confidence: 99%

Two-Photon Photoemission of Ultrathin Film PTCDA Morphologies on Ag(111)

et al. 2008

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Morphology-and layer-dependent electronic structure and dynamics at the PTCDA/Ag(111) interface have been studied with angle-resolved two-photon photoemission. In Stranski-Krastanov growth modes, the exposed wetting layer inhibited the evolution of the vacuum level and valence band to bulk values. For layer-by-layer growth, we observed the transition of electron structure from monolayer to bulk values within eight monolayers. Effective masses and lifetimes of the conduction band and the n = 1 image potential state were measured to be larger for disordered layers. The effective mass was interpreted in the context of charge mobility measurements.

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Luminescence quenching of ordered π-conjugated molecules near a metal surface: Quaterthiophene and PTCDA on Ag(111)

Cited by 66 publications

References 30 publications

Using circularly polarized luminescence to probe exciton coherence in disordered helical aggregates

Using circularly polarized luminescence to probe exciton coherence in disordered helical aggregates

Electronic Decoupling of Aromatic Molecules from a Metal by an Atomically Thin Organic Spacer

Two-Photon Photoemission of Ultrathin Film PTCDA Morphologies on Ag(111)

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