Photon-Mediated Hybridization of Frenkel Excitons in Organic Semiconductor Microcavities

Abstract:We report on the observation of J-aggregates in submonolayer films of R-sexithiophene grown on silicon dioxide. Photoluminescence spectroscopy reveals that submonolayers are formed by molecules lying flat on the substrate with a head to tail configuration. Excitation energy dependence of photoluminescence shows a red-shifted absorption with respect to isolated molecules and a negligible Stokes shift between absorption and emission. The pronounced structural order of J-aggregates is reflected in the fwhm of the emission bands. From time-resolved and low-temperature photoluminescence experiments, we infer a quantum yield of the J-aggregate between 0.6 and 1. The demonstration of spontaneous formation of J-aggregates of π-conjugated systems on amorphous silicon-based substrates can be relevant for the development of organic-inorganic hybrid photonic devices.

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“…Technical support by T. Bonfiglioli, P. Mei, and A. Martiniello is kindly acknowledged. 〈τ〉 ) (A × τ 1 ) + (B × τ 2 ) ) 1.38 ns (3) …”

Section: Discussionmentioning

confidence: 99%

J-Aggregation in α-Sexithiophene Submonolayer Films on Silicon Dioxide

et al. 2006

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“…5,6 Furthermore, their interesting linear and nonlinear optical properties make them promising organic optical materials that could find applications such as ultrasensitive detection of biohazards to superradiance and ultrafast optical switching. [7][8][9][10][11][12][13][14][15][16][17][18][19][20] Cyanine dyes can be self-assembled into mesoscopic Jaggregates by short-range noncovalent interactions such as van der Waals interactions, π-π interactions, and hydrogen bonding. Aggregation is a process that is driven mainly by dispersion forces among the nearest neighbor molecules created by the high polarizability of the π-electrons of the polymethine backbone of cyanine.…”

Section: Introductionmentioning

confidence: 99%

Controlled Formation of the Two-Dimensional TTBC J-Aggregates in an Aqueous Solution

2006

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Strong experimental and theoretical evidence was provided on the controlled formation of the two-dimensional J-aggregates that were assembled in the herringbone morphology. The exciton-band structure formation of 1,1′,3,3′-tetraethyl-5,5′,6,6′-tetrachlorobenzimidazolocarbocyanine (TTBC) J-aggregates was investigated in ionic (NaOH) aqueous solution at room temperature. The control was achieved by changing the [TTBC] at a given [NaOH], or vice versa, and was monitored through the changes in the absorption, fluorescence excitation, and emission spectra. Specific attention was paid to expose the excited-state structure and dynamics through simulations of the excitonic properties, which included diagonal energetic disorder and phononassisted exciton relaxation. Aggregates were characterized by an asymmetrically split Davydov pair, an H-band (∼500 nm, 1300 cm -1 wide, Lorentzian-like) and a J-band (∼590 nm, 235 cm -1 wide, with a band shape typical of a one-dimensional J-aggregate), whose relative intensities showed a strong dependence on the [TTBC]/ [NaOH]. The H-band is favored by high [TTBC] or high [NaOH]. An explanation of the control on the aggregate formation was given by correlating the changes in the absorption with the structural modifications and the subsequent changes in the dynamics, which were induced by variations in the dye and NaOH concentrations. The J-band shape/width was attributed to disorder and disorder-induced intraband phononassisted exciton relaxation. The intraband processes in both bands were estimated to occur in the same time scale (about a picosecond). It has been suggested that the wide energetic gap between the Davydov split bands (3000 cm -1 ) could get bridged by the excitonic states of the loosely coupled chains, in addition to the monomeric species at low [TTBC]. Phonon-assisted interband relaxation, through the band gap states and/or directly from the H-to the J-band, are suggested for accounting the difference between the bandwidths and shapes of the two bands. Energy transfer between the H-band and the monomeric species is suggested as crucial for tuning the relative strengths of the two bands.

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“…Organic semiconductor-based single microcavities composed by high-Q or low-Q reflectors, exhibiting large vacuum Rabi splitting, have been particularly interesting as strong and ultrastrong exciton-photon coupling can be readily attained at room temperature [12][13][14][15][16][17][18][19][20][21][22][23][24] . In this framework, due to the specific excitonic property of organic materials, allowing the ultrastrong coupling regime with a large Rabi splitting to be reached, the demonstration of such coupled multiple organic microcavities, each in the ultrastrong regime, suggests the potential for new physics and applications for tunable polariton-based devices operating at room temperature 25 , with new concepts in quantum information being one example 26 .…”

Section: Introductionmentioning

confidence: 99%

Coupling of exciton-polaritons inlow−Qcoupled microcavities beyond the rotating wave approximation

et al. 2015

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We have demonstrated coupling between a pair of ultrastrong light-matter coupled microcavities composed of neat glassy organic dye films between metallic (silver) mirrors at room temperature. Based upon our modified coupled oscillator model, we have observed that the degeneracy between the Rabi splittings associated with the symmetric and antisymmetric cavity modes is broken by the higher-order anti-resonant terms in the Hamiltonian associated with the breakdown of the rotating wave approximation in the ultrastrong coupling regime. These results are in quantitative agreement with both experiment and transfer matrix modeling. The component cavities are characterized by Q factors around 12 and display a large vacuum Rabi splitting around 1.12 eV between the upper and lower polariton branches, which is about 52% of the excited state energy, thus indicating ultrastrong coupling in each individual cavity. This large splitting is due to the large oscillator strength of the neat dye glass. We have also observed large polariton-induced incidence-side asymmetry in reflection spectra in a coupled cavity pair with one cavity having no exciton.

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Photon-Mediated Hybridization of Frenkel Excitons in Organic Semiconductor Microcavities

Cited by 244 publications

References 20 publications

J-Aggregation in α-Sexithiophene Submonolayer Films on Silicon Dioxide

J-Aggregation in α-Sexithiophene Submonolayer Films on Silicon Dioxide

Controlled Formation of the Two-Dimensional TTBC J-Aggregates in an Aqueous Solution

Coupling of exciton-polaritons inlow−Qcoupled microcavities beyond the rotating wave approximation

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