Showing papers on "Pentacene published in 2009"
TL;DR: Semiconductors deposited by vapor deposition onto the crystalline OTS SAM grow in a favorable two-dimensional layered growth manner which is generally preferred morphologically for high charge carrier transport.
Abstract: Crystalline self-assembled monolayers (SAMs) of organosilane compounds such as octadecyltrimethoxysilane (OTMS) and octadecyltrichlorosilane (OTCS) were deposited by a simple, spin-casting technique onto Si/SiO(2) substrates. Fabrication of the OTMS SAMs and characterization using ellipsometry, contact angle, atomic force microscopy (AFM), grazing angle attenuated total reflectance Fourier transform infrared (GATR-FTIR) spectroscopy and grazing incidence X-ray diffraction (GIXD) are described. The characterization confirms that these monolayers exhibit a well-packed crystalline phase and a remarkably high degree of smoothness. Semiconductors deposited by vapor deposition onto the crystalline OTS SAM grow in a favorable two-dimensional layered growth manner which is generally preferred morphologically for high charge carrier transport. On the OTMS SAM treated dielectric, pentacene OFETs showed hole mobilities as high as 3.0 cm(2)/V x s, while electron mobilities as high as 5.3 cm(2)/V x s were demonstrated for C(60).
547 citations
TL;DR: Hot CT exciton states must be involved in charge separation in organic heterojunction solar cells because hot CT excitons are more weakly bound by the Coulomb potential and more easily dissociated.
Abstract: When a material of low dielectric constant is excited electronically from the absorption of a photon, the Coulomb attraction between the excited electron and the hole gives rise to an atomic H-like quasi-particle called an exciton. The bound electron-hole pair also forms across a material interface, such as the donor/acceptor interface in an organic heterojunction solar cell; the result is a charge-transfer (CT) exciton. On the basis of typical dielectric constants of organic semiconductors and the sizes of conjugated molecules, one can estimate that the binding energy of a CT exciton across a donor/acceptor interface is 1 order of magnitude greater than k(B)T at room temperature (k(B) is the Boltzmann constant and T is the temperature). How can the electron-hole pair escape this Coulomb trap in a successful photovoltaic device? To answer this question, we use a crystalline pentacene thin film as a model system and the ubiquitous image band on the surface as the electron acceptor. We observe, in time-resolved two-photon photoemission, a series of CT excitons with binding energies < or = 0.5 eV below the image band minimum. These CT excitons are essential solutions to the atomic H-like Schrodinger equation with cylindrical symmetry. They are characterized by principal and angular momentum quantum numbers. The binding energy of the lowest lying CT exciton with 1s character is more than 1 order of magnitude higher than k(B)T at room temperature. The CT(1s) exciton is essentially the so-called exciplex and has a very low probability of dissociation. We conclude that hot CT exciton states must be involved in charge separation in organic heterojunction solar cells because (1) in comparison to CT(1s), hot CT excitons are more weakly bound by the Coulomb potential and more easily dissociated, (2) density-of-states of these hot excitons increase with energy in the Coulomb potential, and (3) electronic coupling from a donor exciton to a hot CT exciton across the D/A interface can be higher than that to CT(1s) as expected from energy resonance arguments. We suggest a design principle in organic heterojunction solar cells: there must be strong electronic coupling between molecular excitons in the donor and hot CT excitons across the D/A interface.
367 citations
TL;DR: The physics of microscopic charge transport by using SC-OFETs at metal/semiconductor contacts and along semiconductor/insulator interfaces reveals that interface charge transport in molecular semiconductors is properly described in terms of band transport and localization by charge traps.
348 citations
TL;DR: In the case of parallel configurations of the molecules at the pentacene/C(60) interface, the decay of the lowest charge-transfer state to the ground state is calculated to be very fast; as a result, it can compete with the dissociation process into mobile charge carriers.
Abstract: The exciton-dissociation and charge-recombination processes in organic solar cells based on pentacene/C60 heterojunctions are investigated by means of quantum-mechanical calculations. The electronic couplings and the rates of exciton dissociation and charge recombination have been evaluated for several geometrical configurations of the pentacene/C60 complex, which are relevant to bilayer and bulk heterojunctions. The results suggest that, irrespective of the actual pentacene−fullerene orientation, both pentacene-based and C60-based excitons are able to dissociate efficiently. Also, in the case of parallel configurations of the molecules at the pentacene/C60 interface, the decay of the lowest charge-transfer state to the ground state is calculated to be very fast; as a result, it can compete with the dissociation process into mobile charge carriers. Since parallel configurations are expected to be found more frequently in bulk heterojunctions than in bilayer heterojunctions, the performance of pentacene/C6...
284 citations
TL;DR: New organic semiconductors resulting in high-performance FET devices are described here and the relationship between transistor characteristics and chemical structure is discussed.
248 citations
TL;DR: In this paper, a hopping model is derived that not only quantitatively describes the charge mobility but also explains the observed band-like behavior of the electronic transport in organic materials, in contradiction to the Marcus electron transfer theory.
Abstract: The mechanism of charge transport in organic materials is still controversial from both experimental and theoretical perspectives. At room temperature, molecular deformations interact strongly with the charge carrier both through intermolecular and intramolecular phonons, suggesting a thermally activated hopping mechanism as described by the Marcus electron transfer theory. However, several experimental measurements have indicated that the electronic transport behaves in a ``bandlike'' manner, as indicated by a decrease in mobility with increasing temperature, in contradiction to the Marcus description. Bandlike first-principles calculations based on the Holstein-Peierls model tend to overestimate the charge mobility by about 2 orders of magnitude. Here, a hopping model is derived that not only quantitatively describes the charge mobility but also explains the observed bandlike behavior. This model uses the quantum version of charge-transfer theory coupled with a random-walk simulation of charge diffusion. The results bridge the gap between the two extreme mechanisms. This first-principles method predicts the room-temperature hole mobilities to be 2.4, 2.0, and $0.67\text{ }{\text{cm}}^{2}/\text{V}\text{ }\text{s}$, for rubrene, pentacene, and tetracene, respectively, in good agreement with experiment.
239 citations
TL;DR: Pentacene organic thin-film transistors (OTFTs) with a high-kappa HfLaO dielectric were integrated onto flexible polyimide substrates as discussed by the authors.
Abstract: Pentacene organic thin-film transistors (OTFTs) with a high-kappa HfLaO dielectric were integrated onto flexible polyimide substrates. The pentacene OTFTs exhibited good performance, such as a low subthreshold swing of 0.13 V/decade and a threshold voltage of -1.25 V. The field-effect mobility was 0.13 cm2/Vmiddots at an operating voltage as low as only 2.5 V. These characteristics are attractive for high-switching-speed and low-power applications.
229 citations
TL;DR: In this article, a crystalline, dense octadecylsilane (OTS) surface modification layer was found that promotes two-dimensional semiconductor growth, and higher mobility was consistently achieved for films deposited on crystalline OTS compared to disordered OTS, with mobilities as high as 5.3 and 2.3cm 2 V � 1 s � 1 for C60 and pentacene, respectively.
Abstract: In organic thin film transistors (OTFTs), charge transport occurs in the first few monolayers of the semiconductor near the semiconductor/dielectric interface. Previous work has investigated the roles of dielectric surface energy, roughness, and chemical functionality on performance. However, large discrepancies in performance, even with apparently identical surface treatments,indicate that additionalsurface parametersmust beidentified and controlled in order to optimize OTFTs. Here, a crystalline, dense octadecylsilane (OTS) surface modification layer is found that promotes twodimensional semiconductor growth. Higher mobility is consistently achieved for films deposited on crystalline OTS compared to on disordered OTS, with mobilities as high as 5.3 and 2.3cm 2 V � 1 s � 1 for C60 and pentacene, respectively. This is a significant step toward morphological control of organic semiconductors which is directly linked to their thin film charge carrier transport.
228 citations
TL;DR: The results demonstrate the central role of crystallinity and purity in photogeneration processes and will constrain the design of future photovoltaic devices.
Abstract: We present a comparative study of ultrafast photoconversion dynamics in tetracene (Tc) and pentacene (Pc) single crystals and Pc films using optical pump-probe spectroscopy. Photoinduced absorption in Tc and Pc crystals is activated and temperature-independent, respectively, demonstrating dominant singlettriplet exciton fission. In Pc films (as well as C60-doped films) this decay channel is suppressed by electron trapping. These results demonstrate the central role of crystallinity and purity in photogeneration processes and will constrain the design of future photovoltaic devices.
227 citations
TL;DR: In this paper, a cross-linked poly(4-vinylphenol) (PVP) was investigated as new gate dielectric materials for lowvoltage thin-film transistors.
Abstract: Cross-linked polymer films were investigated as new gate dielectric materials for low-voltage thin-film transistors. Poly(4-vinylphenol) (PVP) was cross-linked through esterification reactions with commercially available bifunctional anhydrides, acyl chlorides, and carboxylic acids. The polymer dielectric films were evaluated based on surface morphology, capacitance, leakage current, and their compatibility with organic semiconductors. Thin insulating PVP films cross-linked with dianhydrides yielded a capacitance as high as 400 nF/cm2 with leakage currents below 10−8 A/cm2. Organic thin-film transistors (OTFTs) fabricated on these gate dielectric layers exhibited charge carrier mobilities as high as 3 cm2/(V s) for p-channel pentacene on octadecyltriethoxylsilane (OTS)-modified PVP and 0.045 cm2/(V s) for n-channel perfluorinated copper phthalocyanine (FCuPc).
223 citations
TL;DR: In this paper, microelectrostatic computations are performed to clarify the nature of the electronic structure and geminate pair energetics at the pentacene/C 60 interface, as archetype for an interface between a donor molecule and a fullerene electron acceptor.
Abstract: Organic semiconductors are characterized by localized states whose energies are predominantly determined by electrostatic interactions with their immediate molecular environment. As a result, the details of the energy landscape at heterojunctions between different organic semiconductors cannot simply be deduced from those of the individual semiconductors, and they have so far remained largely unexplored. Here, microelectrostatic computations are performed to clarify the nature of the electronic structure and geminate pair energetics at the pentacene/C 60 interface, as archetype for an interface between a donor molecule and a fullerene electron acceptor. The size and orientation of the molecular quadrupole moments, determined by material choice, crystal orientation, and thermodynamic growth parameters of the semiconductors, dominate the interface energetics. Not only do quadrupoles produce direct electrostatic interactions with charge carriers, but, in addition, the discontinuity of the quadrupole field at the interface induces permanent interface dipoles. That discontinuity is particularly striking for an interface with C 60 molecules, which by virtue of their symmetry possess no quadrupole. Consequently, at a pentacene/C 6o interface, both the vacuum-level shift and geminate pair dissociation critically depend on the orientation of the pentacene π-system relative to the adjacent C 6o .
TL;DR: The photochemical bisdecarbonylation of bridged alpha-diketones (Strating-Zwanenburg reaction) to give the oligoacenes pentacene, hexacenes, and heptacene is investigated in solid inert gas matrices at cryogenic temperatures and allows a comprehensive comparative study of their electronic absorption and infrared spectral properties under identical conditions for the first time.
Abstract: The photochemical bisdecarbonylation of bridged α-diketones (Strating−Zwanenburg reaction) to give the oligoacenes pentacene (2), hexacene (3), and heptacene (4) is investigated in solid inert gas matrices at cryogenic temperatures. The photodecomposition using visible light irradiation cleanly produces the corresponding oligoacene without formation of observable intermediates. This synthetic approach to the higher acenes allows a comprehensive comparative study of their electronic absorption and infrared spectral properties under identical conditions for the first time. In addition, the route makes it possible to investigate the thermal and photochemical stability of these higher acenes and addresses the problem of heptacene stability which dates back almost 70 years. This largest known member of the acene series is found to be unstable at room temperature. Furthermore, all oligoacenes 2−4 undergo a photoredox reaction upon 185 nm excitation, resulting in the concurrent formation of radical cations and a...
TL;DR: In this paper, an exciton fission process that converts one singlet exciton into two triplet excitons was employed to increase the quantum efficiency of an organic multilayer photodetector beyond 100%.
Abstract: We employ an exciton fission process that converts one singlet exciton into two triplet excitons to increase the quantum efficiency of an organic multilayer photodetector beyond 100%. The photodetector incorporates ultrathin alternating donor-acceptor layers of pentacene and C60, respectively. By comparing the quantum efficiency after separate pentacene and C60 photoexcitation we find that singlet exciton fission in pentacene enhances the quantum efficiency by (45±7)%. In quantitative agreement with this result, we also observe that the photocurrent generated from pentacene excitons is decreased by (2.7±0.2)% under an applied magnetic field of H=0.4 T, while the C60 photocurrent is relatively unchanged.
TL;DR: In this article, the first few layers of pentacene TFTs are analyzed and the packing and exact arrangement of molecules in these layers determine the current obtained at an applied voltage.
Abstract: Organic semiconductors are attracting considerable research interest due to already commercialized and potential applications in low-cost electronics such as organic light emitting diode (OLED) displays, thin film transistors and related applications (e.g. TFT sensors), RF identification tags (RFID), smart cards electronic paper etc.). In the field of organic semiconductor research, the material pentacene has developed into a benchmark material because high-performance thin film transistor (TFT) devices are easily and robustly obtained from vacuum-deposited thin films of pentacene on a variety of substrates. Pentacene thin films on silicon oxide are a particularly interesting case because, despite their polycrystalline film morphology (i.e. structural imperfections and small grains), the pentacene TFTs outperform single crystalbased pentacene transistors. The key to understanding the electrical performance of pentacene TFTs lies with the first few layers of pentacene. When a TFT device is switched “on”, the current flows predominantly in the first few molecular layers and the packing and exact arrangement of molecules in these layers determine the current obtained at an applied voltage. The knowledge of the precise packing in the first monolayer is, therefore, crucial to understanding the charge transport properties of pentacene TFTs.
TL;DR: The dialkynylated tetraazapentacene was prepared by a two-step synthesis from the corresponding quinone derivative and is of great interest as a potential organic n-electron-transport material.
Abstract: A new relative of pentacene: The dialkynylated tetraazapentacene (see figure) was prepared by a two-step synthesis from the corresponding quinone derivative. The heteroacene is an air-stable, dark-blue, crystalline material and is of great interest as a potential organic n-electron-transport material.
TL;DR: In this article, the charge-carrier transport characteristics of solution-processable functionalized acene transistors are discussed and strategies for controlling morphologies and crystalline microstructure of soluble acenes with a view to fabricating high performance OFETs are discussed.
Abstract: Solution-processable functionalized acenes have received special attention as promising organic semiconductors in recent years because of their superior intermolecular interactions and solution-processability, and provide useful benchmarks for organic field-effect transistors (OFETs). Charge-carrier transport in organic semiconductor thin films is governed by their morphologies and molecular orientation, so self-assembly of these functionalized acenes during solution processing is an important challenge. This article discusses the charge-carrier transport characteristics of solution- processed functionalized acene transistors and, in particular, focuses on the fine control of the films' morphologies and structural evolution during film-deposition processes such as inkjet printing and post-deposition annealing. We discuss strategies for controlling morphologies and crystalline microstructure of soluble acenes with a view to fabricating high-performance OFETs.
TL;DR: In this article, a bottom-gate organic thin-film transistor (OTFT) with a single crystal of triisopropylsilylethynyl pentacene (TIPS-PEN) as the active layer is developed.
Abstract: A new type of nonvolatile ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) memory based on an organic thin-film transistor (OTFT) with a single crystal of tri-isopropylsilylethynyl pentacene (TIPS-PEN) as the active layer is developed. A bottom-gate OTFT is fabricated with a thin P(VDF-TrFE) film gate insulator on which a one-dimensional ribbon-type TIPS-PEN single crystal, grown via a solvent-exchange method, is positioned between the Au source and drain electrodes. Post-thermal treatment optimizes the interface between the flat, single-crystalline ab plane of TIPS-PEN and the polycrystalline P(VDF-TrFE) surface with characteristic needle-like crystalline lamellae. As a consequence, the memory device exhibits a substantially stable source–drain current modulation with an ON/OFF ratio hysteresis greater than 103, which is superior to a ferroelectric P(VDF-TrFE) OTFT that has a vacuum-evaporated pentacene layer. Data retention longer than 5 × 104 s is additionally achieved in ambient conditions by incorporating an interlayer between the gate electrode and P(VDF-TrFE) thin film. The device is environmentally stable for more than 40 days without additional passivation. The deposition of a seed solution of TIPS-PEN on the chemically micropatterned surface allows fabrication arrays of TIPS-PEN single crystals that can be potentially useful for integrated arrays of ferroelectric polymeric TFT memory.
TL;DR: Differential conductance images taken with a low-temperature scanning tunneling microscope enabled the first observation of the electron probability distribution of the molecular orbitals of a pentacene molecule directly adsorbed on a metal surface.
Abstract: Differential conductance (dI/dV) images taken with a low-temperature scanning tunneling microscope enabled the first observation of the electron probability distribution of the molecular orbitals of a pentacene molecule directly adsorbed on a metal surface. The three highest occupied molecular orbitals (HOMO, HOMO-1, and HOMO-2) and the lowest unoccupied molecular orbital are imaged. Thus dI/dV imaging without any intervening insulating layer permits the visualization of a large variety of molecular orbitals in the electronic cloud of a wide-gap molecule physisorbed on a metal surface.
Book•
23 Feb 2009
TL;DR: Organic Field Effect Transistors presents the state of the art in organic field effect transistors (OFETs), with a particular focus on the materials and techniques useful for making integrated circuits.
TL;DR: In this paper, bis-triisopropylsilylethynyl (TIPS pentacene) films were fabricated with a newly designed system for controlled solution casting with adjustable nitrogen flow and deposition temperature.
TL;DR: In this article, a self-assembled monolayers (SAMs) based on alkyl-phosphonic acids with five different alkyal chain lengths as the gate dielectric was used to construct a pentacene organic thin-film transistors.
Abstract: We have fabricated pentacene organic thin-film transistors (TFTs) using self-assembled monolayers (SAMs) based on alkyl-phosphonic acids with five different alkyl chain lengths as the gate dielectric and investigated the relationship between the SAM chain length and the electrical performance and stability of the transistors. A SAM chain length of 14 carbon atoms provides a maximum TFT mobility of 0.7 cm2/V s, along with an on/off current ratio greater than 105. We have also investigated the bias stress effect in these TFTs and found that the change in drain current is substantially less severe than in pentacene TFTs with polymer gate dielectrics.
TL;DR: In this paper, femtosecond pump-probe experiments were performed with ultrashort laser pulses applied at normal incidence and at an angle of incidence of $65\ifmmode^\circ\else\textdegree\fi{}$ to disentangle singlet and triplet contributions by exploiting the different orientations of the molecular transition dipoles.
Abstract: The exciton dynamics of microcrystalline pentacene films is investigated by femtosecond pump-probe experiments. Measurements are performed with ultrashort laser pulses applied at normal incidence and at an angle of incidence of $65\ifmmode^\circ\else\textdegree\fi{}$ to disentangle singlet and triplet contributions by exploiting the different orientations of the molecular transition dipoles. The results indicate that the initial 70 fs fast relaxation step transforms the optically excited excitons in a reasonable mobile species with strongly reduced radiative transition strength. Fission into triplet excitons takes place on the picosecond time scale as a secondary, thermally activated process and with a small total yield of approximately 2%. Evidence is provided that the dominant species are singlet excitons with excimer character. To the subsequent dynamics contribute diffusion driven exciton-exciton annihilation and trapping of singlet and triplet excitons. Values for diffusion constants and trap densities are extracted by modeling the measurements with rate equations which include singlet and triplet dynamics.
TL;DR: In this paper, a solar cell fabricated from a blend of poly(3-hexylthiophene) (P3HT) as the donor and the cyanopentacenes as acceptors, and found that the acceptors that stack in a 1D "sandwich-herringbone" exhibited the best performance of derivatives.
Abstract: 6,13-Bis(triisopropylsilylethynyl) (TIPS)-pentacene has proven to be a promising soluble p-type material for organic thin film transistors as well as for photovoltaics. In this work, we show that adding electron-withdrawing nitrile functional groups to TIPS-pentacene turns it into an n-type material, which can be used as an acceptor for organic solar cells. Several new cyanopentacenes with different trialkylsilyl functional groups have been synthesized. The HOMO–LUMO energy levels can be tuned by varying the number of nitrile groups, while the trialkylsilyl groups control crystal packing and film morphology. Solar cells were fabricated from a blend of poly(3-hexylthiophene) (P3HT) as the donor and the cyanopentacenes as acceptors, and we found that the acceptors that stack in a 1D “sandwich-herringbone” exhibited the best performance of derivatives in this study. A solar cell fabricated from a blend of P3HT and 2,3-dicyano-6,13-bis-(tricyclopentylsilylethynyl)pentacene (2,3-CN2-TCPS-Pn) exhibited a power conversion efficiency of 0.43% under 100 mW cm−2AM 1.5 illumination.
TL;DR: In this paper, a hysteresis-free transfer curve with very small switch-on voltages was obtained for single-monolayer pentacene active channels with self-assembled monolayers.
Abstract: Pentacene field-effect transistor performance can be improved by modifying metal electrodes with self-assembled monolayers. The dominant role in performance is played by pentacene morphology rather than the work function of the modified electrodes. With optimized processing conditions, hysteresis-free transfer curves with very small switch-on voltages are obtained for single-monolayer pentacene active channels.
TL;DR: The results indicate that the control of both the evaporation behavior and the contact line dynamics in a drying droplet plays an important role in the printing of organic semiconductor films with uniform morphology and desired molecular orientation for the direct-write fabrication of high-performance organic transistors.
Abstract: We demonstrate the influence of the surface wettability of a dielectric substrate on the crystalline microstructure and film morphology of an inkjet-printed organic semiconductor, namely 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS_PEN), using various self-assembled monolayers (SAMs). Self-aligned crystals with highly ordered crystalline structure are developed by printing on hydrophilic surfaces with high surface energy. It is found that the pinning of the contact line induces an outward convective flow as the evaporation proceeds, which results in the nucleation of crystals and the self-assembly of TIPS_PEN molecules from the periphery to the central region of the droplet. However, for hydrophobic surfaces with low surface energy, small agglomerates with random orientation of molecules are formed, which is induced by depinning of the contact line. The field-effect transistors fabricated with self-organized crystals printed on hydrophilic surfaces exhibit a high field-effect mobility of 0.15 cm2 V−...
TL;DR: In this paper, the fabrication of pentacene-based nonvolatile memory thin-film transistors (NVM-TFTs) with thin poly(vinylidene fluoride/trifluoroethylene) ferroelectric gate insulators was reported.
Abstract: We report on the fabrication of pentacene-based nonvolatile memory thin-film transistors (NVM-TFTs) with thin poly(vinylidene fluoride/trifluoroethylene) ferroelectric gate insulators. Our NVM-TFT adopts flexible polyethersulfone substrate and operates under the low voltage write-erase (WR-ER) pulses of ±13∼±20 V with field effect mobilities of 0.1–0.18 cm2/V s, depending on the ferroelectric polymer thickness. Our NVM-TFT displays good memory window (ΔV) of 2.5–8 V and also exhibits WR-ER current ratio of 20–40. The retention properties persist over ∼10 000 s and the dynamic response for WR-ER pulses demonstrates clear distinction of WR-ER states under the short switching pulse of 50 ms.
TL;DR: In this article, the characteristics of thin-film transistors with pentacene active layers and source/drain contact layers consisting of either Au, Au coated with highly reduced graphene oxide (HRG), or plain HRG, are compared.
Abstract: The characteristics of thin-film transistors (TFTs) with pentacene active layers and source/drain contact layers consisting of either Au, Au coated with highly reduced graphene oxide (HRG), or plain HRG, are compared It is shown that the incorporation of HRG as an interfacial material between gold source/drain contacts and pentacene in TFT devices results in improved electrical characteristics The effect of the HRG layer is to improve the gold/pentacene interface leading to better charge injection, lower losses at the interface, and, consequently, higher effective carrier mobility
Patent•
24 Sep 2009TL;DR: In this article, the nanocrystalline forms of metal oxides, including binary metal oxide, perovskite type metal oxide and complex metal oxide, are provided.
Abstract: Nanocrystalline forms of metal oxides, including binary metal oxide, perovskite type metal oxides, and complex metal oxides, including doped metal oxides, are provided. Methods of preparation of the nanocrystals are also provided. The nanocrystals, including uncapped and uncoated metal oxide nanocrystals, can be dispersed in a liquid to provide dispersions that are stable and do not precipitate over a period of time ranging from hours to months. Methods of preparation of the dispersions, and methods of use of the dispersions in forming films, are likewise provided. The films can include an organic, inorganic, or mixed organic/inorganic matrix. The films can be substantially free of all organic materials. The films can be used as coatings, or can be used as dielectric layers in a variety of electronics applications, for example as a dielectric material for an ultracapacitor, which can include a mesoporous material. Or the films can be used as a high-K dielectric in organic field-effect transistors. In various embodiments, a layered gate dielectric can include spin-cast (e.g., 8 nm-diameter) high-K BaTiO 3 nanocrystals and parylene-C for pentacene OFETs.
TL;DR: In this article, the performance of low-voltage pentacene organic field effect transistors (OFETs) with different gate dielectric interfaces is compared and their performance in terms of electrical properties and operational stability is compared.