Polariton-Induced Color Tuning of Thin Dye Layers

Dähne, Lars; Biller, E.Z.; Baumgärtel, H.

doi:10.1002/(sici)1521-3773(19980316)37:5<646::aid-anie646>3.3.co;2-k

Cited by 10 publications

(10 citation statements)

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“…At the same time, our modelling suggests it is the thickness variations which determine how resonant the weakly trapped optical modes are with the exciton. This provides further evidence that our observations are distinct from the aforementioned ‘intrinsic’ polaritons 27 , which have been almost exclusively observed in highly polished and reflective organic single crystals 15 , 46 . Furthermore, these results also suggest that disorder in thickness directly impacts the position of the cavity mode to a greater degree than in well-controlled Fabry-Pérot cavities.…”

Section: Resultssupporting

confidence: 68%

Microcavity-like exciton-polaritons can be the primary photoexcitation in bare organic semiconductors

Pandya

Chen

et al. 2021

Nat Commun

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Strong-coupling between excitons and confined photonic modes can lead to the formation of new quasi-particles termed exciton-polaritons which can display a range of interesting properties such as super-fluidity, ultrafast transport and Bose-Einstein condensation. Strong-coupling typically occurs when an excitonic material is confided in a dielectric or plasmonic microcavity. Here, we show polaritons can form at room temperature in a range of chemically diverse, organic semiconductor thin films, despite the absence of an external cavity. We find evidence of strong light-matter coupling via angle-dependent peak splittings in the reflectivity spectra of the materials and emission from collective polariton states. We additionally show exciton-polaritons are the primary photoexcitation in these organic materials by directly imaging their ultrafast (5 × 106 m s−1), ultralong (~270 nm) transport. These results open-up new fundamental physics and could enable a new generation of organic optoelectronic and light harvesting devices based on cavity-free exciton-polaritons

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Section: Resultssupporting

confidence: 68%

Microcavity-like exciton-polaritons can be the primary photoexcitation in bare organic semiconductors

Pandya

Chen

et al. 2021

Nat Commun

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“…the hydrophobic or van der Waals interactions between the aliphatic carbon chains or aromatic rings. As was demonstrated impressively by Daehne et al, aggregation also occurs for pure dialkylamino-polymethine chains [33,34]. For most of the dyes forming J-aggregates in aqueous solutions, the morphology and structure of the aggregates are unknown.…”

Section: Water Soluble Amphiphilic Carbocyanine Dyesmentioning

confidence: 98%

J‐aggregates of amphiphilic cyanine dyes: Self‐organization of artificial light harvesting complexes

Kirstein¹,

Daehne

2006

International Journal of Photoenergy

132

225

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The simultaneous chemical linkage of cyanine dye chromophores with both hydrophobic and hydrophilic substituents leads to a new type of amphiphilic molecules with the ability of spontaneous self-organization into highly ordered aggregates of various structures and morphologies. These aggregates carry the outstanding optical properties of J-aggregates, namely, efficient exciton coupling and fast exciton energy migration, which are essential for the build up of artificial light harvesting systems. The morphology of the aggregates depends sensitively on the molecular structure of the chemical substituents of the dye chromophore. Accordingly, lamellar ribbon-like structures, vesicles , tubes, and bundles of tubes are found depending on the dyes and the structure can further be altered by addition of surfactants, alcohols, or other additives. Altogether the tubular structure is the most noticeable structural motif of these types of J-aggregates. The optical spectra are characterized in general by a complex exciton spectrum which is composed of several electronic transitions. The spectrum is red-shifted as a total with respect to the monomer absorption and exhibits resonance fluorescence from the lowest energy transition. For the tubular structures, the optical spectra can be related to a structural model. Although the molecules itself are strictly achiral, a pronounced circular dichroism (CD) is observed for the tubular aggregates and explained by unequal distribution of left- and right-handed helicity of the tubes. Photo-induced electron transfer (PET) reactions from the dye aggregates to electron acceptor molecules lead to superquenching which proves the delocalization of the excitation. This property is used to synthesize metal nanoparticles on the aggregate surface by photo-induced reduction of metal ions.

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“…The method is based on the spherulitic crystallization of undercooled amorphous films of dye salts. It enables the variation of not only the crystalline lattice orientation but also the crystalline lattice structure itself . By using different aggregation temperatures, a surprisingly broad range of color was obtained for the same crystal structure.…”

Section: Introductionmentioning

confidence: 99%

Asymmetrical Molecular Aggregation in Spherulitic Dye Films

1999

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A recently developed method of spherulitic crystallization was used for the preparation of highly ordered 80 nm thin films of the dye 1.7-bis(dimethylamino)heptamethinium perchlorate (BDH+ClO4 -). Depending on the crystallization temperature, the film color and surface topography varied widely, while the crystal structure and film thickness remained the same. At low undercooling, two homogeneous regions were obtained. One showed in-plane symmetrical and the other asymmetrical growth behaviors. At high undercooling, a banded spherulitic structure with rainbow-like colors developed, whose formation is attributed to the out-of-plane asymmetrical growth. The spherulitic growth kinetics, microstructure, and optical properties were investigated by optical microscopy, atomic force, and scanning tunneling microscopy in static and real time mode. A molecular mechanism is proposed which originates from different directions of macroscopic growth and microscopic molecular attachment dictated by the three-dimensional crystal lattice. This mechanism is consistent with the optical spectra and surface topography observed. This mechanism explains the exposure of different crystal faces, asymmetrical molecular attachment, fluctuation in growth rate, film thickness, and viscosity in the amorphous phase. Understanding the molecular origins of J-aggregation in thin dye films allows one to control and manipulate the film color almost in the whole visible wavelength range.

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Polariton-Induced Color Tuning of Thin Dye Layers

Cited by 10 publications

References 0 publications

Microcavity-like exciton-polaritons can be the primary photoexcitation in bare organic semiconductors

Microcavity-like exciton-polaritons can be the primary photoexcitation in bare organic semiconductors

J‐aggregates of amphiphilic cyanine dyes: Self‐organization of artificial light harvesting complexes

Asymmetrical Molecular Aggregation in Spherulitic Dye Films

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