Femtosecond investigations of photophysics of ultrafast intersystem crossing in terthiophene by wavelength dependent excitation

Yang, Jiping; Paa, W.; Rentsch, S.

doi:10.1016/s0009-2614(00)00264-5

Cited by 36 publications

(49 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The situation is, however, different considering a twisted singlet excited state as the starting level for the intersystem crossing. In fact, experimental evidence suggesting the existence of an ISC channel involving a twisted S 1 state has been reported for bithiophene and terthiophene 52, 49. Theoretical calculations on terthiophene have also shown that the spin–orbit expectation values increase when raising the twist angle between adjacent rings 17.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

The Low‐Lying Excited States of 2,2′‐Bithiophene: A Theoretical Analysis

et al. 2003

View full text Add to dashboard Cite

The low-energy region of the singlet-->singlet, singlet-->triplet, and triplet-->triplet electronic spectra of 2,2'-bithiophene are studied using multiconfigurational second-order perturbation theory (CASPT2) and extended atomic natural orbitals (ANO) basis sets. The computed vertical, adiabatic, and emission transition energies are in agreement with the available experimental data. The two lowest singlet excited states, 1(1)Bu and 2(1)Bu, are computed to be degenerate, a novel feature of the system to be borne in mind during the rationalization of its photophysics. As regards the observed high triplet quantum yield of the molecule, it is concluded that the triplet states 2(3)Ag and 2(3)Bu, separated about 0.4 eV from the two lowest singlet excited states, can be populated by intersystem crossing from nonplanar singlet states.

show abstract

Section: Resultsmentioning

confidence: 99%

“…Yang et al52 have shown that the triplet formation yield of terthiophene depends on the excitation wavelength. To explain this dependence, the authors have proposed an ISC mechanism with two channels: one starting from the lowest vibrational level of the S 1 state and the other with origin in a twisted S 1 state.…”

Section: Resultsmentioning

confidence: 99%

The Low‐Lying Excited States of 2,2′‐Bithiophene: A Theoretical Analysis

et al. 2003

View full text Add to dashboard Cite

show abstract

“…61 Excitation-dependent ISC lifetimes were measured for 3T, decreasing from 126 to 51 ps between 400 and 374 nm, 60 as were energy-dependent triplet yields; 50 these results suggest increased singlet-triplet coupling as excitation tunes towards the higher-lying triplet level. 50 As the oligomer length is increased further (>4), the S 1 level drops even further below these triplet levels, and ISC rates occurring over several hundred ps or longer. 20,59 These variations in ISC rate with oligomer length may also be intimately tied to a length dependence of the intermonomer dihedral angle, which is thought to increase at smaller oligomer lengths.…”

Section: B Intersystem Crossing In Pcmtmentioning

confidence: 98%

Ultrafast photo-induced nuclear relaxation of a conformationally disordered conjugated polymer probed with transient absorption and femtosecond stimulated Raman spectroscopies

Donohoo-Vallett

Zhou

et al. 2014

The Journal of Chemical Physics

View full text Add to dashboard Cite

A combination of transient absorption (TAS) and femtosecond stimulated Raman (FSRS) spectroscopies were used to interrogate the photo-induced nuclear relaxation dynamics of poly(3-cyclohexyl,4-methylthiophene) (PCMT). The large difference in inter-ring dihedral angles of ground and excited-state PCMT make it an ideal candidate for studying large-amplitude vibrational relaxation associated with exciton trapping. Spectral shifting in the S1 TA spectra on sub-ps timescales (110 ± 20 and 800 ± 100 fs) is similar to spectroscopic signatures of excited-state relaxation observed with related photoexcited conjugated polymers and which have been attributed to exciton localization and a combination of resonant energy transfer and torsional relaxation, respectively. Measurements made with both techniques reveal fast PCMT S1 decay and triplet formation (τS1 = 25-32 ps), which is similar to the excited-state dynamics of short oligothiophenes and highly twisted polyconjugated molecules. On ultrafast timescales FSRS of S1 PCMT offers a new perspective on the nuclear dynamics that underlie localization of excitons in photoexcited conjugated polymers: Spectral dynamics in the C=C stretching region (1400-1600 cm(-1)) include a red-shift of the in-phase C=C stretching frequency, as well as a change in the relative intensity of in-phase and out-of-phase stretch intensities on a timescale of ∼100 fs. Both changes indicate an ultrafast vibrational distortion that increases the conjugation length in the region of the localized excitation and are consistent with exciton self-localization or trapping. Wavelength-dependent excited-state FSRS measurements further demonstrate that the C=C stretching frequency provides a useful spectroscopic handle for interrogating the degree of delocalization in excited conjugated polymers given the selectivity achieved via resonance enhancement.

show abstract

“…Similar behavior has been found by investigating the ultra-fast dynamics of terthiophene, 3T, by wavelength-dependent excitation and it has been attributed to ultra-fast ISC mediated by a twisted non-relaxed excited-state conformation. 26 Given the almost planar structure of rr-3TbT, we might rule out this mechanism. In support of this conclusion, when fs-TA spectra were obtained by exciting at the onset of the absorption band of rr-3TbT (whereby only planar conformers are excited), similar decay/rise time components are found.…”

Section: Introductionmentioning

confidence: 99%

Multifaceted Regioregular Oligo(thieno[3,4-b]thiophene)s Enabled by Tunable Quinoidization and Reduced Energy Band Gap

et al. 2015

View full text Add to dashboard Cite

Thiophene-based materials have occupied a crucial position in the development of organic electronics. However, the energy band gaps of oligo- and polythiophenes are difficult to modulate without resorting to push-pull electronic effects. We describe herein a new series of monodisperse oligo(thieno[3,4-b]thiophene) derivatives with well-defined regioregular structures synthesized efficiently by direct C-H arylation. These compounds show a unique palette of colors and amphoteric redox properties with widely tunable energy band gaps. The capacity to stabilize both cations and anions results in both anodic and cathodic electrochromism. Under excitation, these compounds can produce photoionized states able to interconvert into neutral triplet or form these through singlet exciton fission or intersystem crossing. These features arise from a progressive increase in quinoidization on a fully planar platform making the largest effective conjugation length among hetero-oligomers. Oligo(thieno[3,4-b]thiophene)s might represent the more distinctive family of oligothiophenes of this decade.

show abstract

Femtosecond investigations of photophysics of ultrafast intersystem crossing in terthiophene by wavelength dependent excitation

Cited by 36 publications

References 25 publications

The Low‐Lying Excited States of 2,2′‐Bithiophene: A Theoretical Analysis

The Low‐Lying Excited States of 2,2′‐Bithiophene: A Theoretical Analysis

Ultrafast photo-induced nuclear relaxation of a conformationally disordered conjugated polymer probed with transient absorption and femtosecond stimulated Raman spectroscopies

Multifaceted Regioregular Oligo(thieno[3,4-b]thiophene)s Enabled by Tunable Quinoidization and Reduced Energy Band Gap

Contact Info

Product

Resources

About