Linear and third order nonlinear optical properties of substituted oligothiophenes

Abstract

Articles you may be interested inThird-order nonlinear optical properties of a one-and two-electron spherical quantum dot with and without a hydrogenic impurity Determination of large third-order optical nonlinearities in tetra-tert-butylphthalocyaninatogallium iodide film Ellipsometric study of the poling effect on nonlinear-optical side-chain polymers containing disperse red 1 Low band gap polythiophene derivatives synthesized using the method of Stille coupling have shown good third order nonlinear optical properties. In order to gain more insight into the structure/ property relationship in these materials, we measured the optical properties of a number of oligothiophene derivatives. In addition to linear absorption spectra, we investigated the third order nonlinear optical properties using Z-scan at a number of wavelengths. As in other conjugated oligomers, the properties depend strongly on chain length. We also observe significant dependence on the substituent type, number, and position, with strong enhancement of the oscillator strength for asymmetric substitution. The resonance nonlinear absorption shows strong saturation behavior, in general changing to induced absorption off-resonance. The nonlinear refractive indices were negative near resonance, suggesting the possibility of thermal effects. While off-resonant nonlinear refractive indices were small, in the five substances for which they could be measured, the values were found to be negative, suggesting that resonant enhancement is still playing a role.

Wavelength dependence and figures of merit of ultrafast third-order optical nonlinearity of a conjugated 3,3′-bipyridine derivative

“…Following the spectrum of the molar extinction coefficient, the values of the oscillator strength and the transition dipole moment ͓D͔ of the lowest-energy peak in the linear absorption spectra can be calculated as 0.74 and 7.9, respectively. The values of the molar extinction coefficient, oscillator strength, and transition dipole moment here are in the same range as those reported by Colditz et al 13 for unsubstituted oligothiophenes with two to six thiophene rings and by Keuren et al 12 for substituted oligothiophenes. The values of the oscillator strength and the transition dipole moment here are larger than 0.10 -0.55 and 4.0 -7.7, respectively, for oligothiophene derivatives.…”

“…The values of the oscillator strength and the transition dipole moment here are larger than 0.10 -0.55 and 4.0 -7.7, respectively, for oligothiophene derivatives. 12 The larger oscillator strength ͑and larger transition dipole mo-ment͒ reflects a greater overlap of ground and excited-state wave functions. By varying the number and type of substituents it is possible to shift the bandgaps, increase the oscillator strength, and enhance the NLO properties compared with those of unsubstituted polythiophene.…”

Functionalized oligoarylenes as building blocks for new organic materials

“…Although other functionalyzed oligothiophenes, 122 oligophenylenes 123 and oligo(phenylenevinylene)s 124 have been used as third-order NLO materials, and some preliminary structure±property correlations have been proposed, much work remains to be done to clarify and optimize the understanding of the structure±property relationships in order to provide the right tools to ef®ciently design novel structures to play an important role in the development of third-order NLO materials.…”

Organotin Reagents in Cross‐Coupling Reactions

“…A different approach to oligothiophenes has been reported by Van Keuren et al [200], who coupled 2,5-bis(trimethylstannyl)thiophene (and other stannylthiophenes) with 5,7-dibromo-2,3-didecylthieno[3,4]bipyrazine under controlled conditions. Hicks and Nodwell [201] prepared a series of oligothiophenes with 2-mesitylthio substituents by coupling 2-stannylthiophenes with 2-bromo-5-mesitylthio-thiophenes.…”