Theoretical study of the influence of thermochromic effects on the electronic structure of poly(3-hexylthiophene)

Thémans, B.; Salaneck, W. R.; Brédas, Jean‐Luc

doi:10.1016/0379-6779(89)90546-8

Cited by 180 publications

(54 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[2][3][4][5] In accordance with this observation and our identification of E 0-0 with E α 0 , we found that E α 0 is accurately described by the function E α 0 (n) ≈ (3.58/n + 1.91) eV. Good agreement with the experiment can be directly inferred from Fig.…”

Section: A Comparison With Experimental Spectrasupporting

confidence: 79%

“…where the potential V , gradient ∇V , and Hessian ∇ 2 V are evaluated at the current coordinate center q t of the evolving GWP at time t. As already alluded to above, the second-order Taylor expansion (5) ensures that the ansatz (4) is plausible even for t > 0. Denoting by…”

Section: B Thawed Gaussian Approximationmentioning

confidence: 99%

“…[2][3][4] Bandgap computations confirmed validity of this semi-empirical rule for short polymers as well as its violation for longer chains. 5,6 For a direct comparison with experiments it is, however, crucial to calculate the vibrationally resolved spectra. 7,8 Here, we therefore determine the vibrationally resolved emission spectra of oligothiophenes Tn with two to five rings, i.e., n ∈ {2, 3, 4, 5}, since the vibrational line shape is changing drastically in this range of n. 2 The cost of computing a vibrationally resolved spectrum is much higher than the cost of vertical transition energy calculations since the spectrum calculation requires the knowledge of the involved potential energy surfaces (PESs).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

On-the-fly ab initio semiclassical dynamics: Identifying degrees of freedom essential for emission spectra of oligothiophenes

Wehrle

Šulc

Vaníček

2014

The Journal of Chemical Physics

104

View full text Add to dashboard Cite

Articles you may be interested inVibrationally resolved spectra provide a stringent test of the accuracy of theoretical calculations. We combine the thawed Gaussian approximation (TGA) with an on-the-fly ab initio (OTF-AI) scheme to calculate the vibrationally resolved emission spectra of oligothiophenes with up to five rings. The efficiency of the OTF-AI-TGA permits treating all vibrational degrees of freedom on an equal footing even in pentathiophene with 105 vibrational degrees of freedom, thus obviating the need for the global harmonic approximation, popular for large systems. Besides reproducing almost perfectly the experimental emission spectra, in order to provide a deeper insight into the associated physical and chemical processes, we also develop a novel systematic approach to assess the importance and coupling between individual vibrational degrees of freedom during the dynamics. This allows us to explain how the vibrational line shapes of the oligothiophenes change with increasing number of rings. Furthermore, we observe the dynamical interplay between the quinoid and aromatic characters of individual rings in the oligothiophene chain during the dynamics and confirm that the quinoid character prevails in the center of the chain. © 2014 AIP Publishing LLC.

show abstract

Section: A Comparison With Experimental Spectrasupporting

confidence: 79%

Section: B Thawed Gaussian Approximationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

On-the-fly ab initio semiclassical dynamics: Identifying degrees of freedom essential for emission spectra of oligothiophenes

Wehrle

Šulc

Vaníček

2014

The Journal of Chemical Physics

104

View full text Add to dashboard Cite

show abstract

“…1,2,6 Thermochromism has been inferred from photoemission studies of undoped P3HT, as a function of temperature, 1,2 combined with the optical absorption spectra, 2 and explained on the basis of valence effective Hamiltonian (VEH) quantum chemical calculations, 1,11 without invoking chemical defects.…”

Section: Introductionmentioning

confidence: 99%

Photohole Screening Effects in Polythiophenes with Pendant Groups

et al. 2005

View full text Add to dashboard Cite

We compare two mechanisms that dominate the temperature-dependent changes in electronic structure for poly(3-hexylthiophene-2,5 diyl) (P3HT). Structural changes in the relative orientation and configuration of the aromatic ring backbone are observed to occur over a wide range in temperature and affect the local final state screening in photoemission. There are also changes in conductivity and carrier concentration at lower temperatures leading to altered long-range intramolecular screening of photoholes and final state effects that affect excitation spectroscopies including photoemission. For polyethylenedioxythiophene (PEDOT), temperature-dependent changes in the structure and configuration of the polymer backbone are not as significant, although temperature-dependent final state effects are observed.

show abstract

“…10 Theoretically, Bredas and co-workers reported that the ionic potential of the polythiophene increased gradually as the torsion angle increased from 0 to 90°. 22 This will be very interesting for OSCs application, which is composed of a polymeric donor and a fullerene acceptor, and the deeper lying HOMO of the polymer donor will be beneficial for higher open-circuit voltage (V oc ). 23 Several examples have been reported employing SHE (alkyl side chains) to design deeper HOMO polythiophenes with improved V oc in their OSCs, unfortunately, E g of the polymers became wider together with decreased hole mobility (μ hole ), which resulted in lower short-circuit current density (J sc ), fill factor (FF), and inconspicuous improvement of power conversion efficiency (PCE) compared to P3hT.…”

Section: −5mentioning

confidence: 99%

Intra- and Intermolecular Steric Hindrance Effects Induced Higher Open-Circuit Voltage and Power Conversion Efficiency

Han

Chen

et al. 2015

ACS Macro Lett.

View full text Add to dashboard Cite

A pair of donor−acceptor polymers PBDThDTBT and PBDTchDTBT are synthesized, which share the same conjugated backbone, but are designed with hexyl and cyclohexyl side chains, respectively. The stronger steric hindrance of cyclohexyl endows PBDTchDTBT a deeper lying HOMO energy level of −5.39 eV compared to −5.22 eV for PBDThDTBT. However, PBDThDTBT and PBDTchDTBT exhibit a similar optical bandgap around 1.72 eV and a hole mobility around 10 −5 cm 2 V −1 s −1 . Interestingly, the PBDTchDTBT/PC 71 BM blends exhibited higher hole mobility than PBDThDTBT/PC 71 BM after DIO was added. The higher hole mobility and fibrillar network in the active layer endows PBDTchDTBT higher power conversion efficiency of 7.9%, together with simultaneously improved open-circuit voltage of 0.80 V, short-circuit current density of 13.50 mA cm, and fill factor of 72.74% after a systemic study of their solar cell devices. S emiconducting polymer is considered as the ideal material for next generation large area optoelectronics application in virtue of its superior solution processing and film forming ability.1−5 When a semiconducting polymer is employed, research is mainly focused on its frontier molecular orbital energy levels and optical and optoelectronic characteristics, which have reliance on the polymer's planarity, interchain aggregation, alkyl substituents, and molecular weight.6−9 One simple and effective strategy employed to adjust the energy levels and optical property of a semiconducting polymer is intra-or intermolecular steric hindrance effect (SHE). 10−13However, SHE has been reported with negative effect on molecular self-organization in the donor−acceptor (D−A) oligmers.14 Intermolecular SHE introduced to the polymer backbone could prevent molecular packing and then result in weaker crystallinity.15 Intramolecular SHE may reduce the π-orbital overlap between two adjacent units and lead to undesirable hypochromatic shifted absorption spectra and wide bandgap (E g ), 10,16−20 however, as is well-known, wide absorption spectra, and narrow E g of the absorber are crucial for organic solar cells (OSCs) application. 21Although SHE has been considered as a negative effect for polymer's self-aggregation and effective conjugation, one advantage should be pointed out, that is, SHE can significantly decrease the highest occupied molecular orbital (HOMO) energy levels of the polymer. For example, poly(3-cyclohexylthiophene) (P3chT) exhibited more twisted conjugating backbone than poly(3-hexylthiophene) (P3hT) because of stronger SHE of cyclohexyl than hexyl, which resulted in a larger dihedral angle (θ) between the two adjacent thiophene rings together with a wider E g and a deeper lying HOMO of −5.72 eV, 0.72 eV lower than that of P3hT (−5.0 eV) experimentally.10 Theoretically, Bredas and co-workers reported that the ionic potential of the polythiophene increased gradually as the torsion angle increased from 0 to 90°.22 This

show abstract

Theoretical study of the influence of thermochromic effects on the electronic structure of poly(3-hexylthiophene)

Cited by 180 publications

References 17 publications

On-the-fly ab initio semiclassical dynamics: Identifying degrees of freedom essential for emission spectra of oligothiophenes

On-the-fly ab initio semiclassical dynamics: Identifying degrees of freedom essential for emission spectra of oligothiophenes

Photohole Screening Effects in Polythiophenes with Pendant Groups

Intra- and Intermolecular Steric Hindrance Effects Induced Higher Open-Circuit Voltage and Power Conversion Efficiency

Contact Info

Product

Resources

About