Optical and luminescence characteristics of thermally evaporated pentacene films on Si

Park, S. P.; Kim, S. S.; Kim, J. H.; Whang, C. N.; Im, Seongil

doi:10.1063/1.1471929

Cited by 113 publications

(73 citation statements)

References 15 publications

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“…This value is about 40% smaller than the experimental value, 1.82 eV, reported from ellipsometric spectra of thin pentacene films [21]. This underestimation of gaps by this magnitude is a common deficiency of the GGA functional [22].…”

Section: A Single Moleculecontrasting

confidence: 47%

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Structural and electronic properties of pentacene molecule and molecular pentacene solid

Endres

Fong

Yang

et al. 2004

Computational Materials Science

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The structural and electronic properties of a single pentacene molecule and a pentacene molecular crystal, an organic semiconductor, are examined by a first-principles method based on the generalized gradient approximation of density functional theory. Calculations were carried out for a triclinic unit cell containing two pentacene molecules. The bandwidths of the valence and conduction bands which determine the charge migration mechanism are found to depend strongly on the crystallographic direction. Along the triclinic reciprocal lattice vectors A and B which are orientated approximately perpendicular to the molecular axes the maximal valence (conduction) band width amounts to only 75 (59) meV, even smaller values are obtained for the C direction parallel to molecular axes even less. Along the stacking directions A+B and A-B, however, the maximal valence (conduction) band width is found to reach 145 (260) meV. The value for the conduction band width is larger than estimates for the polaron binding energy but significantly smaller than recent results obtained by semiempirical methods. The single molecule has a HOMO-LUMO gap of about 1.1 eV as deduced from the Kohn-Sham eigenvalue differences. When using the self-consistent field method, which is expected to yield more reliable results, a value of 1.64 eV is obtained. The theoretical value for the band gap in the molecular solid amounts to 1.0 eV at the Γ-point.

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Section: A Single Moleculecontrasting

confidence: 47%

“…In general they are similar to those in graphite (1.42Å). Our results show also smaller bond-lengths for the C atoms near the ends (bonds 1-2, 10-11, 12-13, and [21][22] to their respective neighbors along the x-direction. These bond-lengths are 1.38Å.…”

Section: A Single Moleculementioning

confidence: 49%

Structural and electronic properties of pentacene molecule and molecular pentacene solid

Endres

Fong

Yang

et al. 2004

Computational Materials Science

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“…The series of oligoacenes, benzene being the first element, is a sequence of molecules composed of n co-joined aromatic rings, starting from n = 1 (benzene), n = 2 (naphthalene), etc. Oligoacene crystals have received renewed attention recently due to their potential use in organic thin film devices 11,48 . In our calculations, we solve the Kohn-Sham equations on a regular grid with grid spacing 0.4 a.u.…”

Section: A Benzene and Naphthalenementioning

confidence: 99%

Optical excitations in organic molecules, clusters, and defects studied by first-principles Green’s function methods

Tiago¹,

2006

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Spectroscopic and optical properties of nanosystems and point defects are discussed within the framework of Green's function methods. We use an approach based on evaluating the self-energy in the so-called GW approximation and solving the Bethe-Salpeter equation in the space of singleparticle transitions. Plasmon-pole models or numerical energy integration, which have been used in most of the previous GW calculations, are not used. Fourier transforms of the dielectric function are also avoided. This approach is applied to benzene, naphthalene, passivated silicon clusters (containing more than one hundred atoms), and the F center in LiCl. In the latter, excitonic effects and the 1s → 2p defect line are identified in the energy-resolved dielectric function. We also compare optical spectra obtained by solving the Bethe-Salpeter equation and by using time-dependent density functional theory in the local, adiabatic approximation. From this comparison, we conclude that both methods give similar predictions for optical excitations in benzene and naphthalene, but they differ in the spectra of small silicon clusters. As cluster size increases, both methods predict very low cross section for photoabsorption in the optical and near ultra-violet ranges. For the larger clusters, the computed cross section shows a slow increase as function of photon frequency. Ionization potentials and electron affinities of molecules and clusters are also calculated.

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“…[1][2][3][4][5] The coupling between these compounds including the energy level alignment and possible charge transfer (CT) states are not well understood, but they are crucially important, since they determine to a large extent the resulting electronic and optical properties including absorption and emission cross sections. One of the fundamental properties is photoluminescence (PL), which is also an important way of testing the interactions and the effective energy levels [6][7][8][9] . In order to maximize the potential for coupling effects, good intermixing of the respective two compounds is desirable, for which structural compatibility is beneficial.…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence spectroscopy of pure pentacene, perfluoropentacene, and mixed thin films

Anger

Ossó

Heinemeyer

et al. 2012

The Journal of Chemical Physics

119

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We report detailed temperature dependent photoluminescence (PL) spectra of pentacene (PEN), perfluoropentacene (PFP), and PEN:PFP mixed thin films grown on SiO2. PEN and PFP are particularly suitable for this study, since they are structurally compatible for good intermixing and form a model donor/acceptor system. The PL spectra of PEN are discussed in the context of existing literature and compared to the new findings for PFP. We analyze the optical transitions observed in the spectra of PEN and PFP using time-dependent density functional theory (TD-DFT) calculations. Importantly, for the mixed PEN:PFP film we observe an optical transition in PL at 1.4 eV providing evidence for coupling effects in the blend. We discuss a possible charge-transfer (CT) and provide a tentative scheme of the optical transitions in the blended films.

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Optical and luminescence characteristics of thermally evaporated pentacene films on Si

Cited by 113 publications

References 15 publications

Structural and electronic properties of pentacene molecule and molecular pentacene solid

Structural and electronic properties of pentacene molecule and molecular pentacene solid

Optical excitations in organic molecules, clusters, and defects studied by first-principles Green’s function methods

Photoluminescence spectroscopy of pure pentacene, perfluoropentacene, and mixed thin films

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