Excitation energies of terthiophene and its dioxide derivative: a first-principles study

Sala, Fabio Della; Heinze, H.; Görling, Andreas

doi:10.1016/s0009-2614(01)00332-3

Cited by 50 publications

(23 citation statements)

References 30 publications

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“…As can be noted from Table 3, differences of about 0.2 eV are found between the CASPT2 and TD‐DFT excitation energies for the four lowest states. In contrast, the TD‐DFT excitation energies computed for the 2 1 A 1 (3.43 eV) and 2 3 A 1 (3.35 eV) states56 are underestimated by 0.5–0.6 eV with respect to the CASPT2 values. As a consequence, the two states appear below the 2 3 B 2 state in the TD‐DFT calculations.…”

Section: Resultsmentioning

confidence: 76%

“…Thus, an almost isoenergetic position of the S 1 and T 2 states has been claimed to explain the high triplet‐formation quantum yield in bithiophene and terthiophene 19. 27, 56 Theoretical studies at the semiempirical level point to a higher triplet state, T 4 , as the one mainly involved in the ISC process 26. 60 Our previous research on bithiophene6, 12 allowed us to reach a satisfactory understanding of the ISC mechanism in this molecule.…”

Section: Resultsmentioning

confidence: 99%

“…As a result, the 1 1 B 2 and 2 3 B 2 states are separated by less than 0.2 eV in both twisted conformers. Della Salla et al56 applied time‐dependent density functional theory (TD‐DFT) to characterise the six lowest excited states of terthiophene using a planar C 2 v geometry. Their TD‐DFT results are included in Table 3.…”

Section: Resultsmentioning

confidence: 99%

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A Theoretical Study on the Low‐Lying Excited States of 2,2′:5′,2′′‐Terthiophene and 2,2′:5′,2′′:5′′,2′′′‐Quaterthiophene

2005

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The nature and properties of the low-lying singlet and triplet valence excited states of 2,2':5',2''-terthiophene (terthiophene) and 2,2':5',2'':5'',2'''-quaterthiophene (tetrathiophene) are discussed on the basis of high-level ab initio computations. The spectroscopic features determined experimentally for short alpha-oligothiophenes are rationalised on theoretical grounds. Special attention is devoted to the nonradiative decay process through intersystem crossing (ISC) from the singlet to the triplet manifold, which is known to be relatively less efficient in tetrathiophene. Along the geometry relaxation of the S1 state of terthiophene, the S1 and T2 states become degenerate, which leads to a favourable situation for the occurrence of ISC. The parallel process is expected to be less favoured in tetrathiophene because of the less efficient spin-orbit coupling and the increase of the S1-T2 energy gap.

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Section: Resultsmentioning

confidence: 76%

Section: Resultsmentioning

confidence: 99%

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A Theoretical Study on the Low‐Lying Excited States of 2,2′:5′,2′′‐Terthiophene and 2,2′:5′,2′′:5′′,2′′′‐Quaterthiophene

2005

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“…Among such oligomers, oligothiophenes represent a very important example: their optical properties have been the subject of numerous investigations both experimental and theoretical . In particular the knowledge about the relative energetic position of singlet and triplet excited-states is of fundamental importance to understand the photophysics of oligothiophenes. − …”

Section: Introductionmentioning

confidence: 99%

Theoretical Study of Singlet and Triplet Excitation Energies in Oligothiophenes

Fabiano¹,

Sala²,

Cingolani³

et al. 2005

J. Phys. Chem. A

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We have analyzed singlet and triplet excitation energies in oligothiophenes (up to five rings) using time-dependent density-functional theory (TD-DFT) with different exchange-correlation functionals and compared them with results from the approximate coupled-cluster singles and doubles model (CC2) and experimental data. The excitation energies have been calculated in geometries obtained by TD-DFT optimization of the lowest excited singlet state and in the ground-state geometries of the neutral and anionic systems. TD-DFT methods underestimate photoluminescence energies but the energy difference between singlet and triplet states shows trends with the chain-length similar to CC2. We find that the second triplet excited state is below the first singlet excited state for long oligomers in contrast with the previous assignment of Rentsch et al. (Phys.Chem. Chem. Phys. 1999, 1, 1707). Their photodetachment photoelectron spectroscopy measurements are better described by considering higher triplet excited states.

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“…As a matter of fact, organic dyes, which do not contain thiophene motifs, seem to be in minority. This is part of the reason why excited states of simple thiophene compounds have drawn interest from numerous theoretical perspectives, including spectroscopy, − excited state geometries, ,, and nonadiabatic molecular dynamics. , In this Letter, we discuss the computational conundrum associated with the low-lying bright ππ * singlet excited states of thiophene, short oligothiophenes, and oligothienoacenes (planar fused oligomers). Figure compares the absorption spectra of thiophene computed with linear response time-dependent density functional theory (TDDFT) and a post-Hartree–Fock (post-HF) formalism.…”

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confidence: 99%

Qualitatively Incorrect Features in the TDDFT Spectrum of Thiophene-Based Compounds

Prlj

Curchod

Fabrizio

et al. 2014

J. Phys. Chem. Lett.

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Ab initio molecular electronic structure computations of thiophene-based compounds constitute an active field of research prompted by the growing interest in low-cost materials for organic electronic devices. In particular, the modeling of electronically excited states and other time-dependent phenomena has moved toward the description of more realistic albeit challenging systems. We demonstrate that due to its underlying approximations, time-dependent density functional theory predicts results that are qualitatively incorrect for thiophene and thienoacenes, although not for oligothiophene chains. The failure includes spurious state inversion and excitation characters, wrong distribution of oscillator strengths and erroneous potential energy surfaces. We briefly analyze possible origins of this behavior and identify alternative methods that alleviate these problems.

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Excitation energies of terthiophene and its dioxide derivative: a first-principles study

Cited by 50 publications

References 30 publications

A Theoretical Study on the Low‐Lying Excited States of 2,2′:5′,2′′‐Terthiophene and 2,2′:5′,2′′:5′′,2′′′‐Quaterthiophene

A Theoretical Study on the Low‐Lying Excited States of 2,2′:5′,2′′‐Terthiophene and 2,2′:5′,2′′:5′′,2′′′‐Quaterthiophene

Theoretical Study of Singlet and Triplet Excitation Energies in Oligothiophenes

Qualitatively Incorrect Features in the TDDFT Spectrum of Thiophene-Based Compounds

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