Structual and Optical Studies of Distyrylbenzene Single Crystals

Wu, Chung Chih; DeLong, M. C.; Vardeny, Z. Valy; Ferraris, John P.

doi:10.1016/s0379-6779(02)01192-x

Cited by 70 publications

(61 citation statements)

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“…12 Quaterthiophene is a widely studied molecular material [11][12][13][14][15][16][17][18][19][20][21] which possesses interesting properties for both applications and fundamental research, 22 since it can be regarded as a model system for many molecular materials crystallizing in a herringbone packing arrangement such as oligothiophenes 15,23 and p-oligophenylene vinylenes. 24,25 The crystallographic structure of the low-temperature 4T polymorph is monoclinic with four molecules per unit cell, whose axes are a = 6.09 Å, b = 7.86 Å, and c = 30.48 Å, the angle ␤ between a and c being 91.8°. 12 Since different names can be found in the literature for the axes of the monoclinic unit cell, for the sake of clarity we denote the monoclinic axis as the b axis and the longest axis as the c axis.…”

Section: Crystal Modelmentioning

confidence: 99%

Exciton-phonon coupling in molecular crystals: Synergy between two intramolecular vibrational modes in quaterthiophene single crystals

Silvestri

Tavazzi

Spearman

et al. 2009

The Journal of Chemical Physics

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Exciton-phonon (EP) coupling in molecular crystals is investigated in the case where two intramolecular vibrational modes are involved and a theoretical model is presented which applies when one of the modes is strongly coupled to crystal excitons. The model is used to simulate the low energy portion of the absorption spectra of quaterthiophene (4T) single crystals, for which we find it appropriate to consider a low energy vibrational mode at 161 cm(-1) and an effective strongly coupled high energy mode at 1470 cm(-1). Our numerical results demonstrate that the high energy mode renormalizes the excitonic band, thereby strongly affecting the environment seen by the low energy mode and the overall EP coupling regime. Numerical simulations also confirm the existence of the new coupling regimes "intermediate-I" and "strong-I" already introduced for oligothiophene aggregates [Spano et al., J. Chem. Phys. 127, 184703 (2007)], which arise as a consequence of the large effective mass of low energy excitons in 4T crystals. Comparison with experimental high resolution absorption spectra is also reported and shown to support the model predictions.

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Section: Crystal Modelmentioning

confidence: 99%

Exciton-phonon coupling in molecular crystals: Synergy between two intramolecular vibrational modes in quaterthiophene single crystals

Silvestri

Tavazzi

Spearman

et al. 2009

The Journal of Chemical Physics

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“…Figure 3 shows the adjacent molecules of compound 1 in crystal. The molecules are parallel stacking along the molecular long-axis direction; but the distance (8.3 Å) between the two molecular long-axes is very large, which is much larger than that of 1,4-distyrylbenzene (trans-DSB) (3.8-4.8 Å) [25] . The photoluminescence efficiency of the thin film of compound 1 is 0.73, which is much higher than that of trans-DSB (<0.1).…”

mentioning

confidence: 92%

Progress on the optoelectronic functional organic crystals

Wang

Xie

et al. 2007

SCI CHINA SER B

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Organic crystals constructed by pi-conjugated molecules have been paid great attention to in the field of organic optoelectronic materials. The superiorities of these organic crystal materials, such as high thermal stability, highly ordered structure, and high carrier mobility over the amorphous thin film materials, make them attractive candidates for optoelectronic devices. Single crystal with definite structure provides a model to investigate the basic interactions between the molecules (supramolecular interaction), and the relationship between molecular stacking modes and optoelectronic performance (luminescence and carrier mobility). Through modulating molecular arrangement in organic crystal, the luminescence efficiency of organic crystal has exceeded 80% and carrier mobility has been up to the level of 10 cm 2 ·V −1 ·s −1 . Amplified stimulated emission phenomena have been observed in many crystals. In this paper, we will emphatically introduce the progress in optoelectronic functional organic crystals and some correlative principle.organic crystals, luminescence, mobility, laser, field effect In the past twenty years, great progress has been made in the field of organic optoelectronic functional materials, such as light-emitting diodes (LEDs) [1 -3] , optically pumped lasers [4,5] , and field-effect transistors (FETs) [6][7][8] . Amorphous semiconductor materials have been extensively investigated because of their operational convenience, since the first high efficiency organic light-emitting diode (OLED) [9] was fabricated by Tang et al. using the vacuum deposition method, and the first organic field-effect transistor (OFET) [10] was fabricated by Tsumura et al. using polythiophene thin film. However, many defects (impurity and structural defects) existing in amorphous materials lead to very low carrier mobility, and then sharply influence the performance of organic semiconductor devices. On the contrary, organic crystals usually present higher mobility, attributed to the very low content of impurity and highly ordered molecule arrangement, as well as highly thermal stability. In recent years, organic single-crystal materials and devices have become a novel investigative hotspot.Scientists have begun to pay attention to the optoelectronic behavior of organic crystals since the 1960s.In the year of 1963, electroluminescence was firstly observed in anthracene single-crystals [11] . In 1974, Avanesjan et al. [12] observed the phenomena of optically pumped laser in anthracene crystals. Later, some organic crystals with high quality and large dimension were successfully obtained, along with the gradually mature technology of growing organic single-crystals; then the crystals were used in testing for some important physical phenomena. For example, the phenomena of amplified spontaneous emission (ASE) were observed in different organic crystals [13][14][15] , which make it possible to realize the electrically pumped laser. Electrically pumped laser requires that the materials must possess high carrier mo-

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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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Structual and Optical Studies of Distyrylbenzene Single Crystals

Cited by 70 publications

References 0 publications

Exciton-phonon coupling in molecular crystals: Synergy between two intramolecular vibrational modes in quaterthiophene single crystals

Exciton-phonon coupling in molecular crystals: Synergy between two intramolecular vibrational modes in quaterthiophene single crystals

Progress on the optoelectronic functional organic crystals

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

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