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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.


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TL;DR: In this article, the influence of in situ postannealing treatment of ultra-high vacuum grown polycrystalline pentacene thin film transistor was studied systematically in x-ray diffraction (XRD) data and the atomic force microscopy image.
Abstract: We studied systematically the influence of in situ postannealing treatment of ultrahigh vacuum grown polycrystalline pentacene thin film transistor. The gradual grain growth with the elimination of defects and misoriented crystallites is confirmed in x-ray diffraction (XRD) data and the atomic force microscopy image as the annealing temperature increases. The XRD data reveal that the pentacene molecules are packed parallel to each other in an upright position with a tilting angle of 15.5°. The postannealing results in the enhanced field effect mobility of pentacene organic thin film transistors increases from 0.19±0.04 to 0.49±0.05 cm2/V s after annealing at 90 °C. We suggest that the abnormally small on/off current ratio (∼103) due to the large leakage current is attributed to the conduction via impurity levels originated from the structural isomers of pentacene.

120 citations

Journal ArticleDOI
TL;DR: In this paper, the influence of oxygen on the electronic trap states in a pentacene thin film was studied by carrying out gated four-terminal measurements on thin-film transistors as a function of temperature and without ever exposing the samples to ambient air.
Abstract: We studied the influence of oxygen on the electronic trap states in a pentacene thin film. This was done by carrying out gated four-terminal measurements on thin-film transistors as a function of temperature and without ever exposing the samples to ambient air. Photo-oxidation of pentacene is shown to lead to a peak of trap states centered at 0.28 eV from the mobility edge, with trap densities of the order of ${10}^{18}\text{ }{\text{cm}}^{\ensuremath{-}3}$. As the gate voltage is ramped up, these trap states are occupied at first and cause a reduction in the number of free carriers at a given gate voltage. Moreover, the exposure to oxygen reduces the mobility of the charge carriers above the mobility edge. We correlate the change of these transport parameters with the change of the essential device parameters, i.e., subthreshold performance and effective field-effect mobility. This study supports the assumption of a mobility edge for charge transport and contributes to a detailed understanding of an important degradation mechanism of organic field-effect transistors. Deep traps in an organic field-effect transistor reduce the effective field-effect mobility by reducing the number of free carriers and their mobility above the mobility edge.

120 citations

Journal ArticleDOI
TL;DR: In this article, a simple three-state model for the dynamics of the singlet fission (SF) process is developed, which facilitates the analysis of the relative significance of different factors, such as electronic energies, couplings, and the entropic contributions.
Abstract: A simple three-state model for the dynamics of the singlet fission (SF) process is developed. The model facilitates the analysis of the relative significance of different factors, such as electronic energies, couplings, and the entropic contributions. The entropic contributions to the rates are important; they drive the SF process in endoergic cases (such as tetracene). The anticipated magnitude of entropic contributions is illustrated by simple calculations. By considering a series of three acenes (tetracene, pentacene, and hexacene), we explained the experimentally observed 3 orders of magnitude difference in the rate of SF in tetracene and pentacene and predicted that the rate in hexacene will be slightly faster than in pentacene. This trend is driven by the increased thermodynamic drive for SF (Gibbs free energy difference of the initial excitonic state and two separated triplets). The model also explains experimentally observed fast SF in 5,12-diphenyltetracene. Consistently with the experimental obs...

120 citations

Journal ArticleDOI
02 Nov 2011-ACS Nano
TL;DR: Thin-film morphology studies of inkjet-printed single-droplet organic thin-film transistors (OTFTs) are reported using angle-dependent polarized Raman spectroscopy to determine the degree of molecular order and to spatially resolve the orientation of the conjugated backbones of the 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-Pentacene) molecules.
Abstract: We report thin-film morphology studies of inkjet-printed single-droplet organic thin-film transistors (OTFTs) using angle-dependent polarized Raman spectroscopy. We show this to be an effective technique to determine the degree of molecular order as well as to spatially resolve the orientation of the conjugated backbones of the 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-Pentacene) molecules. The addition of an insulating polymer, polystyrene (PS), does not disrupt the p-p stacking of the TIPS-Pentacene molecules. Blending in fact improves the uniformity of the molecular morphology and the active layer coverage within the device and reduces the variation in molecular orientation between polycrystalline domains. For OTFT performance, blending enhances the saturation mobility from 0.22 ± 0.05 cm2/ (V·s) (TIPS-Pentacene) to 0.72 ± 0.17 cm2/(V·s) (TIPS-Pentacene:PS) in addition to improving the quality of the interface between TIPS-Pentacene and the gate dielectric in the channel, resulting in threshold voltages of ~0 V and steep subthreshold slopes. © 2011 American Chemical Society.

119 citations

Journal ArticleDOI
TL;DR: In this article, the growth of pentacene monolayers is attributed to the formation of a close-packed, crystalline monolayer which seeds the development of the π-stacked multilayer film.
Abstract: Scanning tunneling microscopy with high impedance has been used to image the growth of pentacene thin films on Au(111). Instead of the herringbone structure in bulk solid, pentacene molecules in these thin films form a cofacial, π-stacked crystalline phase with their molecular planes parallel to the surface. The growth of this crystalline phase is attributed to the formation of a close-packed, crystalline monolayer which seeds the growth of the π-stacked multilayer film.

119 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202382
2022176
2021111
2020125
2019151
2018159