High-Resolution Electronic Spectra of Ethylenedioxythiophene Oligomers

Abstract

The photophysical properties of a series of 3,4-ethylenedioxythiophene oligomers (OEDOT) with up to five repeat units are studied as function of conjugation length using absorption, fluorescence, phosphorescence, and triplet-triplet absorption spectroscopy at low temperature in a rigid matrix. At 80 K, a remarkably highly resolved vibrational fine structure can be observed in the all electronic spectra which reveals that the electronic structure of the oligomers strongly couples to two different vibrational modes (approximately 180 and approximately 50 meV). The energies of the 0-0 transitions in absorption, and fluorescence, phosphorescence, and triplet-triplet absorption all show a reciprocal dependence on the inverse number of repeat units. The triplet energies inferred from the phosphorescence spectra are accurately reproduced by quantum chemical DFT calculations using optimized geometries for the singlet ground state (S0) and first excited triplet state (T1). Using vibrational IR and Raman spectroscopy and quantum chemical DFT calculations for the normal modes in the ground state, we have been able to assign the vibrations that couple to the electronic structure to fully symmetric normal modes. The high-energy mode is associated with the well-known carbon-carbon bond stretch vibration, and the low-energy mode involves a deformation of the bond angles within the thiophene rings and a change of C-S bond lengths. Experimentally obtained Huang-Rhys parameters and theoretical normal mode deformations are used to analyze the geometry changes between T1 and S0 and to semiexperimentally predict the geometry in the S1 state for 2EDOT.

On the Conjugation Length for Oligo(ethynylnaphthalene)‐Based Molecular Rods

“…It should be noted that similar strong confinement of the T 1 triplet exciton has been observed for platinum polyyne derivatives. [45] This finding and ours are somewhat different to those reported for ethylenedioxythiophene oligomers [46] and oligo(9,9-dihexyloligofluorene-2,7-diyl)s, [47] where the triplet energies gradually decrease with an increase in monomer units. We speculate of the possibility that triple bonds help decouple organic units at the triplet level, but further studies are clearly required to see if this is a general phenomenon.…”

Synthesis and characterization of PEDOT derivative with carboxyl group and its chemo sensing application as enhanced optical materials

“…400-600 Scm 21 ) for both chemically and electrochemically prepared samples. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] According to recent reports, highly attention paid on potential practical applications of PEDOT is found to sharply increase, especially applications of PEDOT in chemo/bio-sensors area. [1][2][3][4][5][6][7][8] A variety of potential applications have been explored in electrode materials, electronic materials, photoluminescent, membranes, electrochromic devices, supercapacitors, antistatic coatings, corrosion inhibitors, superhydrophobic fiber, energy storage, solar cells, and chemo/ bio-sensor devices owing to these advantages.…”

“…[1][2][3][4][5][6][7][8] A variety of potential applications have been explored in electrode materials, electronic materials, photoluminescent, membranes, electrochromic devices, supercapacitors, antistatic coatings, corrosion inhibitors, superhydrophobic fiber, energy storage, solar cells, and chemo/ bio-sensor devices owing to these advantages. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] According to recent reports, highly attention paid on potential practical applications of PEDOT is found to sharply increase, especially applications of PEDOT in chemo/bio-sensors area. 24 Although the exploration of the field on PEDOT has become increasingly sophisticated, it still possesses some flaws: The optical absorption coefficient of PEDOT is relatively low (7.1 3 10 3 cm 21 at 2.1 eV) and the solubility of PEDOT in water needs be improved by addition of surfactant and introduction of pendant lyophilic groups, which limits its wide applications as optoelectronics and advanced composite materials.…”

Neutral and Oxidized Triisopropylsilyl End‐Capped Oligothienoacenes: A Combined Electrochemical, Spectroscopic, and Theoretical Study

“…UV/Vis absorption and fluorescence spectroscopies have been found to be successful techniques for the investigation of the conformational disorder in p-conjugated compounds and, particularly, in oligothiophenes. [15] Nonfused oligothiophenes present a high conformational disorder in the ground state due to the internal rotation around the interring CÀC bonds. In passing to the first excited state, they exhibit a reversal of the alternating single/double carboncarbon bond pattern (quinoidization) that hinders the free rotation around the inter-ring bonds and planarizes the molecule.…”