Optical absorption of poly(3-alkylthiophenes) at low temperatures

doi:10.1016/0038-1098(89)90087-2

Solid State Communications

Volume 71, Issue 6, August 1989, Pages 435-439

https://doi.org/10.1016/0038-1098(89)90087-2 Get rights and content

Abstract

We present ultra-violet visible optical absorption spectra of thin solid films of four poly(3-alkylthiophenes) between 10 K and room temperature. The thermochromic shift in the optical absorption turns out to be detectable down to about 200 K. An interpretation of the fine structure in the optical spectra is also made in terms of vibronic structure caused by the CC stretching vibration of the thiophene ring close to 1460 cm⁻¹.

References (27)

S. Hotta
Synth. Met.
(1987)
O. Inganäs et al.
Synth. Met.
(1988)
Z.G. Soos et al.
Chem. Phys. Lett.
(1987)
J. Shinar et al.
Synth. Met.
(1987)
Z. Vardeny et al.
Synth. Met.
(1987)
E.F. Steigmeier et al.
Synth. Met.
(1987)
K.Y. Jen et al.
J. Chem. Soc. Chem. Comm.
(1986)
M. Sato et al.
J. Chem. Soc. Chem. Comm.
(1986)
M. Sato et al.
Synth. Met.
(1987)
S. Hotta et al.
Macromol.
(1987)

S.D.D.V. Rughooputh et al.

J. Polym. Sci. Polymer Phys.

W.R. Salaneck et al.

J. Chem. Phys.

(1988)

K. Yoshino et al.

Jpn. J. Appl. Phys.

(1987)

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Optical absorption of poly(3-alkylthiophenes) at low temperatures

Abstract

Synth. Met.

Synth. Met.

Chem. Phys. Lett.

Synth. Met.

Synth. Met.

Synth. Met.

J. Chem. Soc. Chem. Comm.

J. Chem. Soc. Chem. Comm.

Synth. Met.

Macromol.

J. Polym. Sci. Polymer Phys.

J. Chem. Phys.

Jpn. J. Appl. Phys.