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.

Solvent and polymer matrix effects on TIPS-pentacene/polymer blend organic field-effect transistors

Abstract: We report on a systematic study of solvent and polymer matrix effects on the phase segregation behavior of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) blends incorporated into two different amorphous polymer matrices, poly (α-methyl styrene) and poly (triarylamine), and using two solvents, chlorobenzene and tetralin. Optical microscopy, X-ray diffraction analyses, and optical absorption measurements are used to evaluate the film morphology, crystallinity, and optical density, respectively. These analyses are correlated with the extent of vertical segregation of TIPS-pentacene, as observed for the blended films by depth-profile XPS analyses. The microstructure and vertical phase segregation of TIPS-pentacene in blend films are found to be strongly influenced by the choice of solvent. Tetralin, a solvent with a high boiling temperature, was found to be more desirable for achieving distinct phase segregation/crystallization of TIPS-pentacene in blend films and best performance in OFETs with a dual-gate geometry. The electrical properties of top and bottom channels were consistent with the morphological characterization and OFETs processed from tetralin showed higher mobility values than those from chlorobenzene. Further modification of the annealing conditions in the TIPS-pentacene/PTAA/tetralin ternary system led to top-gate OFETs with mobility values up to 2.82 cm2/Vs.

Organic ferroelectric memory cells

Abstract: This invention proposes to make memory using organic materials. The basic structure of the memory cell is a field effect organic transistor using a ferroelectric thin film polymer as gate dielectric. By controlling the gate voltage to polarize the thin film ferroelectric polymer polarized in either an “up” or “down” state, the source-drain current can be controlled between two different values under the same source-drain voltage. The source-drain current thus can be used to represent either a “0” or “1” state. The organic thin film transistor can be made from poly(phenylenes), thiophene oligomers, pentacene, polythiophene, perfluoro copper phthalocyanine or other organic thin films. The ferroelectric thin film can be poly(vinylidene fluoride) (PVDF), poly(vinyldiene-trifluoroethylene) (P(VDF-TrFE)) copolymers, odd-numbered nylons, cyanopolymers, polyureas, or other ferroelectric thin films. As the deposition of these organic thin films can be done at temperatures below 200° C., the memory cell can be made on many kinds of substrates including plastics.

Ultrafast exciton relaxation in microcrystalline pentacene films.

Abstract: The exciton dynamics in microcrystalline pentacene films is investigated by transient absorption measurements with 30 fs time resolution. It is found that the emission from photoexcited Frenkel excitons decays within 70 fs due to the ultrafast formation of an excitonic species with a strongly reduced transition dipole to the ground state and an absorption dipole in the plane of the film. We propose that an excimer exciton is formed and stabilized by changes of the local crystal structure. The subsequent dynamics is dominated by diffusion controlled annihilation and trapping.

Infrared spectroscopy of matrix-isolated polycyclic aromatic hydrocarbon cations. 3. The polyacenes anthracene, tetracene, and pentacene.

Abstract: Gaseous, ionized Polycyclic Aromatic Hydrocarbons (PAH's) are thought to be responsible for a very common family of interstellar infrared emission bands. Unfortunately, very little infrared spectroscopic data are available on ionized PAH's. Here we present the near- and mid-infrared spectra of the polyacene cations anthracene, tetracene, and pentacene. We also report the vibrational frequencies and relative intensities of the pentacene anion. The cation bands corresponding to the CC modes are typically about 10-20 times more intense than those of the CH out-of-plane bending vibrations. For the cations the CC stretching and CH in-plane bending modes give rise to bands which are an order of magnitude stronger than for the neutral species, and the CH out-of-plane bends produce bands which are 3-20 times weaker than in the neutral species. This behavior is similar to that found for most other PAH cations. The most intense PAH cation bands fall within the envelopes of the most intense interstellar features. The strongest absorptions in the polyacenes anthracene, tetracene, and pentacene tend to group around 1400 / cm (between about 1340 and 1500 / cm) and near 1180 /cm, regions of only moderate interstellar emission. These very strong polyacene bands tend to fall in gaps in the spectra of the other PAH cations studied to date suggesting that while PAHs with polyacene structures may contribute to specific regions of the interstellar emission spectra, they are not dominant members of the interstellar PAH family.

Low temperature thin film transistor fabrication

Abstract: The invention broadens the range of materials and processes that are available for Thin Film Transistor (TFT) devices by providing in the device structure an organic semiconductor layer that is in contact with an inorganic mixed oxide gate insulator involving room temperature processing at up to 150 degrees C. A TFT of the invention has a pentacene semiconductor layer in contact with a barium zirconate titanate gate oxide layer formed on a polycarbonate transparent substrate employing at least one of the techniques of sputtering, evaporation and laser ablation.