Conformations and torsional potentials of poly(3-hexylthiophene) oligomers: Density functional calculations up to the dodecamer

Bhatta, Ram S.; Yimer, Yeneneh; Tsige, Mesfin; Perry, David S.

doi:10.1016/j.comptc.2012.06.026

Cited by 38 publications

(78 citation statements)

References 42 publications

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“…For P3HT both planar and non‐planar stable geometries have been reported, depending on the side‐chain orientation . At the B3LYP/6–31+G** level of theory the non‐planar backbone has an energy of 0.03 eV lower (per monomer) than the planar backbone (evaluated in a 10‐mer) . This indicates that chain conformations in the bulk are predominantly determined by interchain van‐der‐Waals and Coulomb interactions, a conclusion also drawn from calculations of molecular dimers .…”

Section: Theoretical Studies Of Hole Transport In P3ht and P3ht:pcbm mentioning

confidence: 99%

“…In the majority of cases, parameters of an existing force field were refined in order to reproduce the torsional potential between thiophene units and electrostatic potential around an isolated oligomer . The parameterization has been subsequently refined to account for the change in the backbone potential with the oligomer length . To this end, atomistic simulations have been used to analyze proposed packing arrangements of three P3HT polymorphs, phases I,

I'

, and II, and to scrutinize the effect of regioregularity on paracrystalline, dynamic, and static nematic order parameters .…”

Section: Theoretical Studies Of Hole Transport In P3ht and P3ht:pcbm mentioning

confidence: 99%

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Charge Carrier Transport and Photogeneration in P3HT:PCBM Photovoltaic Blends

Laquai

Andrienko

Mauer

et al. 2015

Macromol. Rapid Commun.

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We review the charge transport and photogeneration in bulk-heterojunction solar cells made from blend films of regioregular poly(3-hexylthiophene) (RR-P3HT) and methanofullerene (PCBM). The charge transport, specifically the hole mobility in the RR-P3HT phase of the polymer:fullerene photovoltaic blend, is dramatically affected by thermal annealing. The hole mobility increases more than three orders of magnitude and reaches a value of up to 2×10 -4 cm 2 V -1 s -1 after the thermal annealing process, as a result of an improved semi-crystallinity of the film. This significant increase of the hole mobility balances the electron and hole mobilities in a photovoltaic blend in turn reducing spacecharge formation and it is the most important factor for the strong enhancement of the photovoltaic efficiency compared to an as cast, that is, non-annealed device. In fact, the balanced charge carrier mobility in RR-P3HT:PCBM blends in combination with a field-

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Section: Theoretical Studies Of Hole Transport In P3ht and P3ht:pcbm mentioning

confidence: 99%

I'

, and II, and to scrutinize the effect of regioregularity on paracrystalline, dynamic, and static nematic order parameters .…”

Section: Theoretical Studies Of Hole Transport In P3ht and P3ht:pcbm mentioning

confidence: 99%

Charge Carrier Transport and Photogeneration in P3HT:PCBM Photovoltaic Blends

Laquai

Andrienko

Mauer

et al. 2015

Macromol. Rapid Commun.

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“…In contrast to Bhatta et al, 39 we distinguish head, tail, and central thiophene units as they feature different charge distributions. [40][41][42][43] A list of all modified force field parameters is contained in Tables 1 and 2. 2).…”

Section: B Atomistic Molecular Dynamics Simulationsmentioning

confidence: 99%

Structure of P3HT crystals, thin films, and solutions by UV/Vis spectral analysis

Böckmann

Schemme

Jong

et al. 2015

Phys. Chem. Chem. Phys.

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Optical absorption spectra of poly(3-hexylthiophene) (P3HT) are calculated in solution, spin-coated thin films, and the bulk crystal using a multiscale simulation approach. The structure of the amorphous thin film is obtained from coarse grained molecular dynamics (MD) simulations and subsequent back-mapping onto an atomistic force field representation. The absorption spectra are computed using TDDFT by statistically averaging over an ensemble of molecules taken from the MD simulations. Experimental UV/Vis spectra of spin-coated thin films and solutions are recorded with varying ratios of 'good' versus 'poor' solvent. The theoretical approach is able to faithfully predict the spectral position in the various phases and offers fundamental insight into the cause of any spectral shifts. The position of the main absorption peak is found to be chiefly determined by the level of torsion between the thiophene rings inside each molecule, while intermolecular effects are less important. Hence, optical absorption spectra hold valuable clues about the microscopic structure of disordered P3HT phases.

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“…The geometry optimizations of each of these molecules were performed using dispersion corrected Becke's three-parameter Lee-YangÀParr (B3LYP) exchange-correlation functional combined with 6-31G ⁄ basis set without any constraint [29,30]. The B3LYP functional was chosen for geometry optimization because it has been proven from our previous studies that it produces accurate geometries of conjugated systems [31][32][33]. Three different RS functionals such as CAM-B3LYP [17], LC-BLYP [18] and wB97XD [19], which have default w values of 0.33 Bohr À1 , 0.47 Bohr À1 and 0.20 Bohr À1 , respectively are chosen.…”

Section: Methodsmentioning

confidence: 99%

Tuning range-separated DFT functionals for accurate orbital energy modeling of conjugated molecules

Bhatta

Pellicane

Tsige

2015

Computational and Theoretical Chemistry

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a b s t r a c tDensity functional theory (DFT) calculations with range-separated (RS) functionals are important for orbital energy modeling of conjugated molecules that involve charge transfer excitation. However, the accuracy of the computed results depends on the range-separation parameter (w), and the optimal values of w for a wide range of conjugated systems has hitherto been missing. Herein, orbital energy modeling of twelve representative conjugated molecules, that are promising electron-donors in bulk heterojunction-based organic photovoltaic devices, are benchmarked using DFT and time-dependent DFT (TD-DFT) with three RS functionals (LC-BLYP, wB97XD and CAM-B3LYP). The results using the RS functionals under consideration with default values of w deviate largely from the experimental values (mean signed error (MSE) on HOMO are 2.1 eV, 0.93 eV and 1.5 eV, and MSE on vertical excitation energies are 0.47 eV, 0.55 eV and 0.82 eV, respectively). Computation of orbital energies using tuned range-separation parameter for these RS functionals in the range of 0.05 6 w P 0.5 Bohr À1 indicates that w plays a significant role on the accuracy of the ground and the excited state energies. We found that the accurate orbital energies of conjugated systems can be predicted using values of w between 0.1 and 0.15 Bohr À1 , much smaller than the default values of 0.47, 0.33 and 0.20 Bohr À1 used in LC-BLYP, CAM-B3LYP and wB97XD, respectively.

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Conformations and torsional potentials of poly(3-hexylthiophene) oligomers: Density functional calculations up to the dodecamer

Cited by 38 publications

References 42 publications

Charge Carrier Transport and Photogeneration in P3HT:PCBM Photovoltaic Blends

Charge Carrier Transport and Photogeneration in P3HT:PCBM Photovoltaic Blends

Structure of P3HT crystals, thin films, and solutions by UV/Vis spectral analysis

Tuning range-separated DFT functionals for accurate orbital energy modeling of conjugated molecules

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