Orientation-Dependent Electronic Structures and Optical Properties of the P3HT:PCBM Interface: A First-Principles GW-BSE Study

Li, Long Hua; Kontsevoi, Oleg Y.; Freeman, Arthur J

doi:10.1021/jp501295p

Cited by 15 publications

(31 citation statements)

References 38 publications

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“…A similar coupling effect was seen by Troisi et al, 76 Marchiori and Koehler, 65 and Li et al 64 in their studies of how packing of the small molecules and PCBM fullerenes affects charge transfer states. Unfortunately, it is challenging to account for intermolecular coupling in DFT calculations because of the large system sizes involved in these calculations.…”

Section: Resultssupporting

confidence: 77%

Petascale Simulations of the Morphology and the Molecular Interface of Bulk Heterojunctions

et al. 2016

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Understanding how additives interact and segregate within bulk heterojunction (BHJ) thin films is critical for exercising control over structure at multiple length scales and delivering improvements in photovoltaic performance. The morphological evolution of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) blends that are commensurate with the size of a BHJ thin film is examined using petascale coarse-grained molecular dynamics simulations. Comparisons between two-component and three-component systems containing short P3HT chains as additives undergoing thermal annealing demonstrate that the short chains alter the morphology in apparently useful ways: they efficiently migrate to the P3HT/PCBM interface, increasing the P3HT domain size and interfacial area. Simulation results agree with depth profiles determined from neutron reflectometry measurements that reveal PCBM enrichment near substrate and air interfaces but a decrease in that PCBM enrichment when a small amount of short P3HT chains are integrated into the BHJ blend. Atomistic simulations of the P3HT/PCBM blend interfaces show a nonmonotonic dependence of the interfacial thickness as a function of number of repeat units in the oligomeric P3HT additive, and the thiophene rings orient parallel to the interfacial plane as they approach the PCBM domain. Using the nanoscale geometries of the P3HT oligomers, LUMO and HOMO energy levels calculated by density functional theory are found to be invariant across the donor/acceptor interface. These connections between additives, processing, and morphology at all length scales are generally useful for efforts to improve device performance.

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Section: Resultssupporting

confidence: 77%

Petascale Simulations of the Morphology and the Molecular Interface of Bulk Heterojunctions

et al. 2016

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“…As done by many researchers [27][28][29][30], we consider both edge-on and face-on configurations. In the edge-on configuration one end of Pc aims at the hexagons/pentagons on C 60 , while in the face-on configuration, the plane of Pc faces the hexagons/pentagons on C 60 .…”

Section: Results: Superintermolecular Orbitalsmentioning

confidence: 99%

Superintermolecular orbitals in the C60 -pentacene complex

Zhang¹,

Gardner²,

Latta³

et al. 2016

Phys. Rev. A

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We report a group of unusually big molecular orbitals in the C60/pentacene complex. Our firstprinciples density functional calculation shows that these orbitals are very delocalized and cover both C60 and pentacene, which we call superintermolecular orbitals or SIMOs. Their spatial extension can reach 1 nm or larger. Optically, SIMOs are dark. Different from ordinary unoccupied molecular orbitals, SIMOs have a very weak Coulomb and exchange interaction. Their energy levels are very similar to the native superatomic molecular orbitals in C60, and can be approximately characterized by orbital angular momentum quantum numbers. They have a distinctive spatial preference. These features fit the key characters of charge-generation states that channel initially-bound electrons and holes into free charge carriers. Thus, our finding is important for C60/pentacene photovoltaics.

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“…The adverse scaling of GW with the number of atoms in the system and the slow convergence of quasiparticle energies with respect to the number of unoccupied states that are included in the calculation pose serve challenges to the tractable system size, which is easily exceeded by most surface adsorbate systems of interest. Nonetheless, an increasing number of GW calculations for organic adsorbates on surfaces is being reported in the literature [96,97,98,99,100,101,102,103,104,105,106,107,108,109].…”

Section: Density-functional Theory Calculations For Surfaces and Intementioning

confidence: 99%

Global and local aspects of the surface potential landscape for energy level alignment at organic-ZnO interfaces

Stähler

Rinke

2017

Chemical Physics

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Hybrid systems of organic and inorganic semiconductors are a promising route for the development of novel opto-electronic and light-harvesting devices. A key ingredient for achieving a superior functionality by means of a hybrid system is the right relative position of energy levels at the interfaces of the two material classes. In this Perspective , we address the sensitivity of the potential energy landscape at various ZnO surfaces, a key ingredient for interfacial energy level alignment, by combining one- and two-photon photoelectron spectroscopy with density-functional theory calculations (DFT). We show that even very large work function changes (>> 2.5 eV) do not necessarily have to be accompanied by surface band bending in ZnO. Band bending – if it does occur – may be localized to few Åor extend over hundreds of nanometers with very different results for the surface work function and energy level alignment. Managing the delicate balance of different interface manipulation mechanisms in organic-inorganic hybrid systems will be a major challenge towards future applications

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Orientation-Dependent Electronic Structures and Optical Properties of the P3HT:PCBM Interface: A First-Principles GW-BSE Study

Cited by 15 publications

References 38 publications

Petascale Simulations of the Morphology and the Molecular Interface of Bulk Heterojunctions

Petascale Simulations of the Morphology and the Molecular Interface of Bulk Heterojunctions

Superintermolecular orbitals in the C60 -pentacene complex

Global and local aspects of the surface potential landscape for energy level alignment at organic-ZnO interfaces

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