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.

Imaging molecular orbitals by scanning tunneling microscopy on a passivated semiconductor.

Abstract: Decoupling the electronic properties of a molecule from a substrate is of crucial importance for the development of single-molecule electronics. This is achieved here by adsorbing pentacene molecules at low temperature on a hydrogenated Si(100) surface (12 K). The low temperature (5 K) scanning tunneling microscope (STM) topography of the single pentacene molecule at the energy of the highest occupied molecular orbital (HOMO) tunnel resonance clearly resembles the native HOMO of the free molecule. The negligible electronic coupling between the molecule and the substrate is confirmed by theoretical STM topography and diffusion barrier energy calculations.

Growth of organic ultrathin films studied by Penning ionization electron and ultraviolet photoelectron spectroscopies: Pentacene

Abstract: Penning ionization electron spectroscopy was applied to ultrathin pentacene films [monolayer (0.3 nm thick) to dozens of layers] prepared by vapor deposition under different conditions. Remarkable differences were found among the Penning ionization electron spectra (PIES). The local electron distribution of each molecular orbital (MO) protruding from the film surface was probed and the relation between the MO shape and the molecular orientation was investigated. Deposition onto a metal substrate without a crystallographical surface yields a crystalline film at room temperature. The molecules are oriented with the long axes almost perpendicular to the substrate and make the σ bands of the PIES by far stronger than the π bands. In the pure π region, the π9 and π7 MOs having large distribution at the long-axis end provide more intense bands than other π MOs. On the metal substrate held at 213 K, molecules form an amorphous film with the long axes inclined a little on average. The π and σ bands exhibit compar...

Ambipolar Charge Injection and Transport in a Single Pentacene Monolayer Island

Abstract: Electrons and holes are locally injected in a single pentacene monolayer island The two-dimensional distribution and concentration of the injected carriers are measured by electrical force microscopy In crystalline monolayer islands, both carriers are delocalized over the whole island On a disordered monolayer, carriers stay localized at their injection point These results provide insight into the electronic properties, at the nanometer scale, of organic monolayers governing performances of organic transistors and molecular devices

Thermal and mechanical cracking in bis(triisopropylsilylethnyl)pentacene thin films

Abstract: Bis(triisopropylsilylethnyl) pentacene (TIPS pentacene) was synthesized to increase its solubility in common liquid solvents and, at the same time, enhance the π–π stacking between neighboring acenes in the crystallized state in comparison with unmodified pentacene. Hot-stage microscopy experiments revealed that during heating voids develop along the long axis of the TIPS pentacene films {along the [210] direction/parallel to the (120) planes} and crystals overlap along the short axis {along the [120] direction/parallel to the (210) planes}. From molecular mechanics simulations, the predominant twin boundaries of (120) and commonly observed cracking planes of (120), (120), and (210) had relatively low surface energies in comparison with planes with similar Miller indices. Organic thin-film transistors with TIPS pentacene as the active layer were fabricated, and the mobility values decreased from 0.4–1.0 cm2/V s before cracking to ∼0.2 cm2/V s after cracking. To maintain the high charge carrier mobility of TIPS pentacene devices, these cracks should be avoided. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3631–3641, 2006