Showing papers on "Pentacene published in 1996"
TL;DR: In this article, a maximum field effect mobility of 0.038 cm−2'V−1'1's−1 is reported for devices incorporating pentacene films deposited at room temperature.
Abstract: Pentacene films deposited with molecular beam deposition have been fabricated and characterized with respect to structure and morphology using x‐ray diffraction and scanning electron microscopy. Metal‐insulator semiconductor field‐effect transistor devices based on such films were used to study their transport properties. A maximum field‐effect mobility of 0.038 cm−2 V−1 s−1 is reported for devices incorporating pentacene films deposited at room temperature. The structural characterization revealed the coexistence of two phases: the thermodynamically stable single‐crystal phase and the kinetically favored, metastable thin‐film phase. Such mixed phase films were produced when low deposition rates were used in combination with a substrate temperature of 55 °C. Mixed phase films had transport properties inferior to films consisting solely of one phase, while amorphous films deposited at low surface mobility conditions had extremely low conductivity. Use of prepurified pentacene as source material resulted in...
661 citations
TL;DR: In this article, a simple thermal conversion yields transistors with carrier mobilities as high as 9×10−3 cm2, V−1/s−1 and current modulations of the order of 105.
Abstract: Metal‐insulator‐semiconductor field‐effect transistors have been constructed with pentacene as the active semiconductor. The pentacene is processed by spin coating from a soluble precursor. A simple thermal conversion yields transistors with carrier mobilities as high as 9×10−3 cm2 V−1 s−1 and current modulations of the order of 105. Depletion of charge is essential to the device operation. Data for an invertor exhibiting voltage amplification are presented.
168 citations
TL;DR: In this article, thin-film transistors were fabricated using vacuum-deposition pentacene as the semiconductor and field effect mobilities as high as 0.4 cm2 V-1 s-1 were obtained, which were attributed to the single-crystal nature of the deposited films.
Abstract: Thin-film transistors (TFTs) were fabricated using vacuum deposited pentacene as the semiconductor. Field-effect mobilities as high as 0.4 cm2 V-1 s-1 were obtained, which were attributed to the single-crystal nature of the deposited films.
162 citations
TL;DR: In this paper, the current density induced in planar hydrocarbons by an external magnetic field is computed and mapped using Coupled Hartree-Fock theory, and results of useful accuracy can be obtained with modest (6-31G) basis sets by employing a continuous gauge transformation.
Abstract: Coupled Hartree-Fock theory is used to compute and map the current density induced in planar hydrocarbons by an external magnetic field. Results of useful accuracy can be obtained with modest (6-31G**) basis sets by employing a continuous gauge transformation. Maps are presented and discussed for benzene, naphthalene, anthracene, tetracene, pentacene, heptacene, and biphenylene. © 1996 John Wiley & Sons, Inc.
140 citations
TL;DR: The orientation of the transition dipole moment of the pentacene molecules in the a′ b′ -plane of the crystal was determined by taking the birefringence of the crystalline matrix into account as discussed by the authors.
55 citations
TL;DR: In this paper, an atomic force microscopy (OFM) analysis of pentacene films was performed using pulsed laser deposition (PLD) and showed that PLD leads to a reduction in surface roughness, which can be reduced further using heated substrates.
Abstract: Thin films of pentacene were deposited by thermal evaporation and by pulsed laser deposition (PLD). Surface characterization using atomic force microscopy shows that PLD leads to a reduction in surface roughness, which can be reduced further using heated substrates. Observation of enhanced field‐effect carrier mobilities in the PLD films, together with increased electrical conductivity and reduced activation energy for electrical conduction, is consistent with increased molecular ordering in the pentacene films and suggests a direct correlation between molecular ordering in the bulk and surface roughness.
39 citations
26 Jun 1996
TL;DR: In this article, the authors used pentacene, a fused-ring aromatic hydrocarbon, as the active material for organic TFTs with field effect mobility greater than 0.6 cm/sup 2/V-s and on/off ratio greater than 10/sup 8.
Abstract: Organic thin film transistors (TFTs), are of interest for use in broad area electronic applications. In active matrix liquid crystal displays, AMLCDs, for example, organic TFTs would allow the use of inexpensive, light-weight, and mechanically rugged plastic substrates as an alternative to glass. To date, organic TFTs have exhibited field effect mobilities and current on/off ratios too low to be useful for display technology. For example, organic TFTs based on /spl alpha/-sexithienyl typically have a maximum mobility near 0.05 cm/sup 2//V-s and a maximum on/off ration of about 10/sup 6/. We have fabricated organic TFTs using pentacene, a fused-ring aromatic hydrocarbon, as the active material. These new devices have field-effect mobility greater than 0.6 cm/sup 2//V-s and on/off ratio greater than 10/sup 8/.
29 citations
TL;DR: In this paper, the authors applied methods developed for single molecule spectroscopy to small ensembles and recorded high-resolution fluorescence-excitation spectra for pentacene in all substitutional sites of a pterphenyl single crystal.
21 citations
TL;DR: Weak satellites in S1←S0 excitation spectra of pentacene in pterphenyl due to position-specific 13C isotope shifts were observed in this article.
Abstract: Weak satellites in S1←S0 excitation spectra of natural‐abundance pentacene in p‐terphenyl due to position‐specific 13C isotope shifts were observed. An assignment of these satellites to the various carbon positions is derived. The extremely narrow inhomogeneous linewidth allowed selective excitation of pentacene molecules with 13C in specific positions. Spectra of the magnetic‐resonance transition between triplet sublevels of such ensembles, and of individual pentacene molecules showed position‐specific 13C hyperfine broadening.
18 citations
TL;DR: In this paper, the exponential decay of the fluorescence intensity autocorrelation function for a single molecule in the microsecond time regime was analyzed to determine the population (k23) and depopulation (k31) rate of the metastable triplet state.
Abstract: Dilute mixed molecular crystals of pentacene in naphthalene were prepared by cosublimation of the two compounds. Single pentacene molecules could be detected in the thin platelets by fluorescence excitation spectroscopy. By analyzing the exponential decay of the fluorescence intensity autocorrelation function for a single molecule in the microsecond time regime we could determine the population (k23) and depopulation (k31) rate of the metastable triplet state. The increase of the population rate k23 by a factor of ∼ 4 when compared to pentacene in p-terphenyl is responsible for the weaker fluorescence signals of single pentacene molecules in naphthalene crystals.
12 citations
TL;DR: In this paper, a new approach to the description of the photoenhanced current is proposed, which includes generation and recombination processes induced by oxygen centers, to explain the experimental currentvoltage and current-light intensity relations.
Abstract: Photoenhanced current measurements carried out on polycrystalline pentacene layers are presented. A new approach to the description of the photoenhanced current is proposed. The inclusion of generation and recombination processes induced by oxygen centres enables us to explain the experimental current-voltage and current-light intensity relations.