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John E Anthony - One of the best experts on this subject based on the ideXlab platform.
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Substituent effects on the electronic characteristics of Pentacene derivatives for organic electronic devices: Dioxolane-substituted Pentacene derivatives with triisopropylsilylethynyl functional groups
Journal of the American Chemical Society, 2012Co-Authors: Olga Lobanova Griffith, John E Anthony, Adolphus G. Jones, Dennis L. LichtenbergerAbstract:The intramolecular electronic structures and intermolecular electronic interactions of 6,13-bis(triisopropylsilylethynyl)Pentacene (TIPS Pentacene), 6,14-bis-(triisopropylsilylethynyl)-1,3,9,11-tetraoxa-dicyclopenta[b,m]-Pentacene (TP-5 Pentacene), and 2,2,10,10-tetraethyl-6,14-bis-(triisopropylsilylethynyl)-1,3,9,11-tetraoxa-dicyclopenta[b,m]Pentacene (EtTP-5 Pentacene) have been investigated by the combination of gas-phase and solid-phase photoelectron spectroscopy measurements. Further insight has been provided by electrochemical measurements in solution, and the principles that emerge are supported by electronic structure calculations. The measurements show that the energies of electron transfer such as the reorganization energies, ionization energies, charge-injection barriers, polarization energies, and HOMO–LUMO energy gaps are strongly dependent on the particular functionalization of the Pentacene core. The ionization energy trends as a function of the substitution observed for molecules in the ga...
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a survey of electron deficient Pentacenes as acceptors in polymer bulk heterojunction solar cells
Chemical Science, 2011Co-Authors: Zhong Li, Rawad Hallani, George G Malliaras, Balaji Purushothaman, Sean Parkin, John E AnthonyAbstract:We have prepared, characterized and surveyed device performance for a series of electron deficient Pentacenes for use as acceptors in polymer bulk heterojunction solar cells, using P3HT as the donor material. All of the materials reported here behaved as acceptors, and variations in the position and nature of the electron-withdrawing group on the Pentacene core allowed tuning of device open-circuit voltage. Photocurrent was strongly correlated with the Pentacene crystal packing motif; materials with 2D π-stacking interactions performed poorly compared with materials exhibiting 1D π-stacking interactions. The best Pentacene acceptors gave repeatable device efficiency in excess of 1.2%, compared with 3.5% exhibited for PCBM-based devices.
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environmental and operational stability of solution processed 6 13 bis triisopropyl silylethynyl Pentacene thin film transistors
Organic Electronics, 2009Co-Authors: Sung Kyu Park, John E Anthony, Devin A Mourey, T N JacksonAbstract:We report operational and environmental stability of solution-processed organic thin film transistors (OTFTs) using the small molecule organic semiconductor 6,13-bis(triisopropyl-silylethynyl) Pentacene (TIPS-Pentacene). Typical drop-cast TIPS-Pentacene OTFTs show strong molecular ordering and relatively stable characteristics with air and illumination compared to vapor-deposited Pentacene OTFTs. For short channel length devices, TIPS-Pentacene OTFTs undergo significant degradation with bias-stress, possibly due to operation at large drive currents and large local power dissipation as well as built-in charges in the channel area.
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morphology and molecular orientation of thin film bis triisopropylsilylethynyl Pentacene
Journal of Materials Research, 2007Co-Authors: Jihua Chen, David C Martin, John E AnthonyAbstract:As a modification to the insoluble and herringbone-structured Pentacene, bis(triisopropylsilylethynyl) (TIPS) Pentacene has two bulky side groups, leading to good solubility in common organic solvents and regular π–π stacking arrangements in the crystalline state. Solution processing of TIPS–Pentacene thin films was investigated as a function of various process parameters in this work. Electron diffraction results suggested that TIPS–Pentacene molecules tended to align with the acene unit edge on to the substrate, touching down with their bulky side groups. In a TIPS–Pentacene polycrystalline film, the long axis of individual crystallite is [2 1 0], while the shorter axis is [1 ¯ 2 0]. High-resolution electron microscopy was used to study the local crystal structure and characteristic defects of TIPS–Pentacene thin films. Due to the nonaromatic side groups, TIPS–Pentacene was found to be significantly more sensitive to the electron beam (critical dose J c = 0.05 C/cm 2 at 300 kV) than Pentacene itself (J c = 0.2 C/cm 2 at 100 kV).
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Ultrafast carrier dynamics in Pentacene, functionalized Pentacene, tetracene, and rubrene single crystals
Applied Physics Letters, 2006Co-Authors: Oksana Ostroverkhova, John E Anthony, Oana D. Jurchescu, David G. Cooke, Frank A. Hegmann, Vitaly Podzorov, Michael Gershenson, Thomas PalstraAbstract:We measure the transient photoconductivity in Pentacene, functionalized Pentacene, tetracene, and rubrene single crystals using optical pump-terahertz probe techniques. In all of the samples studied, we observe subpicosecond charge photogeneration and a peak photoconductive response that increases as the temperature decreases from 297 down to 20K, indicative of bandlike transport. Similar decay dynamics are observed at room temperature, but at low temperatures the decay dynamics measured in Pentacene, rubrene, and tetracene crystals are much faster than those observed in functionalized Pentacene crystals, revealing different charge trapping properties.
J.-l. Jean-luc Brédas - One of the best experts on this subject based on the ideXlab platform.
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exciton dissociation and charge recombination processes in Pentacene c60 solar cells theoretical insight into the impact of interface geometry
Journal of the American Chemical Society, 2009Co-Authors: Yuanping Yi, Veaceslav Coropceanu, J.-l. Jean-luc BrédasAbstract: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...
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Exciton-dissociation and charge-recombination processes in Pentacene/C 60 solar cells: Theoretical insight into the impact of interface geometry
Journal of the American Chemical Society, 2009Co-Authors: Yuanping Yi, Veaceslav Coropceanu, J.-l. Jean-luc BrédasAbstract:The exciton-dissociation and charge-recombination processes in organic solar cells based on Pentacene/C-60 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/C-60 complex, which are relevant to bilayer and bulk heterojunctions. The results suggest that, irrespective of the actual Pentacene-fullerene orientation, both Pentacene-based and C-60-based excitons are able to dissociate efficiently. Also, 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. Since parallel configurations are expected to be found more frequently in bulk heterojunctions than in bilayer heterojunctions, the performance of Pentacene/C-60 bulk-heterojunction solar cells is likely to be more affected by charge recombination than that of bilayer devices.
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the vibrational reorganization energy in Pentacene molecular influences on charge transport
Journal of the American Chemical Society, 2002Co-Authors: Nadine E Gruhn, Veaceslav Coropceanu, Demetrio A Da Silva Filho, Tonja G Bill, Massimo Malagoli, And Antoine Kahn, J.-l. Jean-luc BrédasAbstract:The reorganization energy in Pentacene is reported on the basis of a joint experimental and theoretical study of Pentacene ionization using high-resolution gas-phase photoelectron spectroscopy, semiempirical intermediate neglect of differential overlap calculations, and first-principles correlated quantum-mechanical calculations at MP2 and density functional theory levels. The reorganization energy upon positive ionization of Pentacene is determined both experimentally and theoretically to be remarkably low. This is one key element that allows one to rationalize the extremely high hole mobilities recently measured in Pentacene single crystals.
Yunseok Jang - One of the best experts on this subject based on the ideXlab platform.
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effect of the phase states of self assembled monolayers on Pentacene growth and thin film transistor characteristics
Journal of the American Chemical Society, 2008Co-Authors: Minkyu Hwang, Yunseok JangAbstract:To investigate the effects of the phase state (ordered or disordered) of self-assembled monolayers (SAMs) on the growth mode of Pentacene films and the performance of organic thin-film transistors (OTFTs), we deposited Pentacene molecules on SAMs of octadecyltrichlorosilane (ODTS) with different alkyl-chain orientations at various substrate temperatures (30, 60, and 90 °C). We found that the SAM phase state played an important role in both cases. Pentacene films grown on relatively highly ordered SAMs were found to have a higher crystallinity and a better interconnectivity between the Pentacene domains, which directly serves to enhance the field-effect mobility, than those grown on disordered SAMs. Furthermore, the differences in crystallinity and field-effect mobility between Pentacene films grown on ordered and disordered substrates increased with increasing substrate temperature. These results can be possibly explained by (1) a quasi-epitaxy growth of the Pentacene film on the ordered ODTS monolayer and (2) the temperature-dependent alkyl chain mobility of the ODTS monolayers.
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effect of the phase states of self assembled monolayers on Pentacene growth and thin film transistor characteristics
Journal of the American Chemical Society, 2008Co-Authors: Minkyu Hwang, Yunseok JangAbstract:To investigate the effects of the phase state (ordered or disordered) of self-assembled monolayers (SAMs) on the growth mode of Pentacene films and the performance of organic thin-film transistors (OTFTs), we deposited Pentacene molecules on SAMs of octadecyltrichlorosilane (ODTS) with different alkyl-chain orientations at various substrate temperatures (30, 60, and 90 °C). We found that the SAM phase state played an important role in both cases. Pentacene films grown on relatively highly ordered SAMs were found to have a higher crystallinity and a better interconnectivity between the Pentacene domains, which directly serves to enhance the field-effect mobility, than those grown on disordered SAMs. Furthermore, the differences in crystallinity and field-effect mobility between Pentacene films grown on ordered and disordered substrates increased with increasing substrate temperature. These results can be possibly explained by (1) a quasi-epitaxy growth of the Pentacene film on the ordered ODTS monolayer an...
Veaceslav Coropceanu - One of the best experts on this subject based on the ideXlab platform.
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exciton dissociation and charge recombination processes in Pentacene c60 solar cells theoretical insight into the impact of interface geometry
Journal of the American Chemical Society, 2009Co-Authors: Yuanping Yi, Veaceslav Coropceanu, J.-l. Jean-luc BrédasAbstract: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...
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Exciton-dissociation and charge-recombination processes in Pentacene/C 60 solar cells: Theoretical insight into the impact of interface geometry
Journal of the American Chemical Society, 2009Co-Authors: Yuanping Yi, Veaceslav Coropceanu, J.-l. Jean-luc BrédasAbstract:The exciton-dissociation and charge-recombination processes in organic solar cells based on Pentacene/C-60 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/C-60 complex, which are relevant to bilayer and bulk heterojunctions. The results suggest that, irrespective of the actual Pentacene-fullerene orientation, both Pentacene-based and C-60-based excitons are able to dissociate efficiently. Also, 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. Since parallel configurations are expected to be found more frequently in bulk heterojunctions than in bilayer heterojunctions, the performance of Pentacene/C-60 bulk-heterojunction solar cells is likely to be more affected by charge recombination than that of bilayer devices.
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the vibrational reorganization energy in Pentacene molecular influences on charge transport
Journal of the American Chemical Society, 2002Co-Authors: Nadine E Gruhn, Veaceslav Coropceanu, Demetrio A Da Silva Filho, Tonja G Bill, Massimo Malagoli, And Antoine Kahn, J.-l. Jean-luc BrédasAbstract:The reorganization energy in Pentacene is reported on the basis of a joint experimental and theoretical study of Pentacene ionization using high-resolution gas-phase photoelectron spectroscopy, semiempirical intermediate neglect of differential overlap calculations, and first-principles correlated quantum-mechanical calculations at MP2 and density functional theory levels. The reorganization energy upon positive ionization of Pentacene is determined both experimentally and theoretically to be remarkably low. This is one key element that allows one to rationalize the extremely high hole mobilities recently measured in Pentacene single crystals.
Yuanping Yi - One of the best experts on this subject based on the ideXlab platform.
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exciton dissociation and charge recombination processes in Pentacene c60 solar cells theoretical insight into the impact of interface geometry
Journal of the American Chemical Society, 2009Co-Authors: Yuanping Yi, Veaceslav Coropceanu, J.-l. Jean-luc BrédasAbstract: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...
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Exciton-dissociation and charge-recombination processes in Pentacene/C 60 solar cells: Theoretical insight into the impact of interface geometry
Journal of the American Chemical Society, 2009Co-Authors: Yuanping Yi, Veaceslav Coropceanu, J.-l. Jean-luc BrédasAbstract:The exciton-dissociation and charge-recombination processes in organic solar cells based on Pentacene/C-60 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/C-60 complex, which are relevant to bilayer and bulk heterojunctions. The results suggest that, irrespective of the actual Pentacene-fullerene orientation, both Pentacene-based and C-60-based excitons are able to dissociate efficiently. Also, 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. Since parallel configurations are expected to be found more frequently in bulk heterojunctions than in bilayer heterojunctions, the performance of Pentacene/C-60 bulk-heterojunction solar cells is likely to be more affected by charge recombination than that of bilayer devices.
