Pentacene

About: Pentacene is a research topic. Over the lifetime, 5051 publications have been published within this topic receiving 161481 citations. The topic is also known as: 2,3:6,7-dibenzanthracene & benzo[b]naphthacene.

Simulation of vapor-phase deposition and growth of a pentacene thin film on C60 (001).

Abstract: Current research in organic electronics is clearly evidencing that the strive to produce efficient organic electronic devices requires high performance materials that can only be realized through a rational design [Special11]. Although polymer-based systems are at the moment the most appealing for market applications, mainly because of their solution processability, small molecule-based devices possess potential for commercialization, presenting comparable performances and a better batch-to-batch reproducibility of their properties [Walker11]. The interest in small molecules of well defined crystalline structure arises also from the fine control over final morphologies that can be achieved through vapour-phase growth techniques [Ruiz04, Rolin10], control that allows, with respect to polymer devices, a deeper understanding of the structure-electronic properties relationships. Indeed building an efficient electronic device (e. g. a solar cell) coincides to a large extent with the fine tuning of the electronic properties at the different interfaces, typically metal-organic, inorganic-organic, and organic-organic. In this communication we focus on the latter interface between two of the most studied p-and n-type molecular organic semiconductors, pentacene (A5) and C 60 fullerene. These materials have been recently employed in producing rather efficient thin film bilayer solar cells [Yoo04, Mayer04, Yoo07, Cheyns07, Dissanayake07], ambipolar field effect transistors [Kuwahara04, Yan09, Cosseddu10] and low-voltage-operating organic complementary inverters [Na09]. The relative simplicity and the good performances of C 60 /A5 heterojunctions has stimulated theoretical research on the electronic processes occurring at the interface: density functional theory [Yi09], valence-bond Hartree-Fock [Linares10] and microelectrostatic calculations [Verlaak09] have been employed in studying model interfaces of increasing complexity. These studies coherently underline the importance of relative molecular orientations and positions in determining the interface dipole and electronic couplings, i.e. the key factors governing exciton transport and fission, charge generation and separation [Rao10]. This in turn means that improving computational predictions of the molecular organization at the interface is fundamental to understanding experimental systems of great interest. This task can in principle be tackled by using classical atomistic force fields, but it is definitely not a straightforward one. Indeed, it has been recently recognized that molecular organizations at the interface depend on the preparation process and not just on thermodynamic state of the system, so that imitating the experimental preparation techniques is often necessary to produce realistic morphologies [Liu08, Cheung08, MacKenzie10, Clancy11, Beljonne11]. For this specific system, Clancy and co-workers applied classical simulations at both coarse-grained [Choudhary06] and atomistic detail [Goose07] to study some aspects of the pentacene …

Structural order in perfluoropentacene thin films and heterostructures with pentacene.

Abstract: Synchrotron x-ray diffraction reciprocal space mapping was performed on perfluoropentacene (PFP) thin films on SiO2 in order to determine the crystal structure of a novel, substrate-induced thin film phase to be monoclinic with unit cell parameters of a = 15.76 ± 0.02 A, b = 4.51 ± 0.02 A, c = 11.48 ± 0.02 A, and β = 90.4 ± 0.1°. Moreover, layered and co-deposited heterostructures of PFP and pentacene (P) were investigated by specular and grazing-incidence x-ray diffraction, atomic force microscopy, and Fourier-transform infrared spectroscopy. For a ca. three-monolayers-thick PFP film grown on a P underlayer, slightly increased lattice spacing was found. In contrast, co-deposited P/PFP films form a new mixed-crystal structure with no detectable degree of phase separation. These results highlight the structural complexity of these technically relevant molecular heterojunctions for use in organic electronics.

In-situ probe of gate dielectric-semiconductor interfacial order in organic transistors: origin and control of large performance sensitivities.

Abstract: Organic thin film transistor (OTFT) performance is highly materials interface-dependent, and dramatic performance enhancements can be achieved by properly modifying the semiconductor/gate dielectric interface. However, the origin of these effects is not well understood, as this is a classic “buried interface” problem that has traditionally been difficult to address. Here we address the question of how n-octadecylsilane (OTS)–derived self-assembled monolayers (SAMs) on Si/SiO2 gate dielectrics affect the OTFT performance of the archetypical small-molecule p-type semiconductors P-BTDT (phenylbenzo[d,d]thieno[3,2-b;4,5-b]dithiophene) and pentacene using combined in situ sum frequency generation spectroscopy, atomic force microscopy, and grazing incidence and reflectance X-ray scattering. The molecular order and orientation of the OTFT components at the dielectric/semiconductor interface is probed as a function of SAM growth mode in order to understand how this impacts the overlying semiconductor growth mode,...