Capacitive behavior of pentacene-based diodes: Quasistatic dielectric constant and dielectric strength

Kim, Chang‐Hyun; Yaghmazadeh, Omid; Tondelier, Denis; Jeong, Yong Bin; Bonnassieux, Yvan; Horowitz, Gilles

doi:10.1063/1.3574661

Cited by 105 publications

(81 citation statements)

References 34 publications

(52 reference statements)

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“…The fully screened dielectric constants are in excellent agreement with the measured values of ε. 4,18,26,27 For pentacene, ε full is also close to the values of 3.2 and 3.6, obtained by Sharifzadeh et al 3 from GW calculations within the random phase approximation (RPA). Indeed, the SCS method solves the RPA equation for a collection of QHOs in the dipole approximation.…”

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confidence: 62%

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Electrodynamic response and stability of molecular crystals

Schatschneider

Liang²,

Reilly

et al. 2013

Phys. Rev. B

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We show that electrodynamic dipolar interactions, responsible for long-range fluctuations in matter, play a significant role in the stability of molecular crystals. Density functional theory calculations with van der Waals interactions determined from a semilocal "atom-in-a-molecule" model result in a large overestimation of the dielectric constants and sublimation enthalpies for polyacene crystals from naphthalene to pentacene, whereas an accurate treatment of nonlocal electrodynamic response leads to an agreement with the measured values for both quantities. Our findings suggest that collective response effects play a substantial role not only for optical excitations, but also for cohesive properties of noncovalently bound molecular crystals. Polyacene molecular crystals form a fundamental class of aromatic solids, and have been extensively studied as potential materials for organic electronics. [1][2][3] It is understood that the optical properties of polyacenes are very sensitive to longrange intra-and intermolecular electrodynamic interactions. This is reflected by shifts in the optical absorption frequencies upon increasing the molecule size or upon solid formation, 4 and is further exhibited by the visible color of oligoacene crystals, which changes from transparent in naphthalene and anthracene, to bright orange in tetracene, and deep blue in pentacene. 4,5 The optical absorption spectrum is directly related to the polarizability through the Kramers-Kronig transformation.6 Therefore, the observed changes in the optical spectrum upon crystallization of polyacenes are accompanied by a change in the molecular polarizability. In addition, these changes in polarization should directly impact the crystal lattice energy. However, the effect of electrodynamic intermolecular interactions on the cohesive properties of molecular crystals remains poorly understood. In this Rapid Communication, we show that the dipolar electrodynamic coupling between polyacene molecules reduces the solid dielectric constant by 15%, and has an impact of up to 0.5 eV per molecule on the computed van der Waals (vdW) energies and sublimation enthalpies of these molecular crystals. Our results imply that electrodynamic response is crucial for describing both the cohesive energy and the optical properties of molecular crystals, also providing strong quantitative support to empirical relations between stability and refractive index of molecular crystals. 7Polyacene crystals are extended aromatic networks characterized by polarizable π clouds. Therefore, an appreciable part of the crystal lattice energy stems from ubiquitous attractive vdW dispersion interactions. When studying the cohesion of molecular systems, for example, using densityfunctional theory (DFT) 8,9 or classical potentials, 10 the vdW energy is typically computed using effective polarizabilities for hybridized "atoms" inside a molecule. It is common to approximate the frequency-dependent polarizability of every atom using a single effective excitation frequency (also called t...

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confidence: 62%

“…ε 18,27 experiments are less than 2% in lattice parameters and unit cell volumes. Similar agreement is also found for the internal molecular geometries, for which the PBE+vdW method predicts the C-C distances with an accuracy of 2% in comparison with x-ray measurements.…”

mentioning

confidence: 99%

Electrodynamic response and stability of molecular crystals

Schatschneider

Liang²,

Reilly

et al. 2013

Phys. Rev. B

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“…[5][6][7] In the absence of a dedicated highly doped contact zone, the electrostatic infl uence of the contact built-in potential does not reduce to a socalled depletion region, but can spread throughout the whole organic semiconductor bulk; this aspect, together with a widely observed Fermi-level pinning, makes the charge-injection barrier a macroscopic bottleneck for current fl ow, which manifests itself as a signifi cant contact resistance ( R c ). [8][9][10][11] Organic fi lms are composed of molecules weakly bound to each other by van der Waals forces, which are in competition with molecule-substrate interactions.…”

Section: −3mentioning

confidence: 99%

Decoupling the Effects of Self‐Assembled Monolayers on Gold, Silver, and Copper Organic Transistor Contacts

Kim

Hlaing

Hong

et al. 2014

Adv Materials Inter

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In bottom‐contact organic field‐effect transistors (OFETs), the functionalization of source/drain electrodes leads to a tailored surface chemistry for film growth and controlled interface energetics for charge injection. This report describes a comprehensive investigation into separating and correlating the energetic and morphological effects of a self‐assembled monolayers (SAMs) treatment on Au, Ag, and Cu electrodes. Fluorinated 5,11‐bis(triethylsilylethynyl) anthradithiophene (diF‐TES‐ADT) and pentafluorobenzenethiol (PFBT) are employed as a soluble small‐molecule semiconductor and a SAM material, respectively. Upon SAM modification, the Cu electrode devices benefit from a particularly dramatic performance improvement, closely approaching the performance of OFETs with PFBT‐Au and PFBT‐Ag. Ultraviolet photoemission spectroscopy, polarized optical microscopy, grazing‐incidence wide‐angle X‐ray scattering elucidate the metal work function change and templated crystal growth with high crystallinity resulting from SAMs. The transmission‐line method separates the channel and contact properties from the measured OFET current–voltage data, which conclusively describes the impact of the SAMs on charge injection and transport behavior.

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“…[26][27][28] while those for the organic semiconductors rubrene, pentacene, and poly(3-hyxylthiophene) (P3HT) are 3.3-3.9, 2.6, and 4.4, respectively. [29][30][31] The derived value of ~5 lies between the two groups and possibly reflects the weaker ionic or stronger covalent character of CuSCN due to the -SCN constituent.…”

Section: Metal-insulator-semiconductor Capacitors Based On Cuscnmentioning

confidence: 99%