51
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Kotadiya NB, Mondal A, Blom PWM, Andrienko D, Wetzelaer GJAH. A window to trap-free charge transport in organic semiconducting thin films. NATURE MATERIALS 2019; 18:1182-1186. [PMID: 31548633 DOI: 10.1038/s41563-019-0473-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 07/31/2019] [Indexed: 06/10/2023]
Abstract
Organic semiconductors, which serve as the active component in devices, such as solar cells, light-emitting diodes and field-effect transistors1, often exhibit highly unipolar charge transport, meaning that they predominantly conduct either electrons or holes. Here, we identify an energy window inside which organic semiconductors do not experience charge trapping for device-relevant thicknesses in the range of 100 to 300 nm, leading to trap-free charge transport of both carriers. When the ionization energy of a material surpasses 6 eV, hole trapping will limit the hole transport, whereas an electron affinity lower than 3.6 eV will give rise to trap-limited electron transport. When both energy levels are within this window, trap-free bipolar charge transport occurs. Based on simulations, water clusters are proposed to be the source of hole trapping. Organic semiconductors with energy levels situated within this energy window may lead to optoelectronic devices with enhanced performance. However, for blue-emitting light-emitting diodes, which require an energy gap of 3 eV, removing or disabling charge traps will remain a challenge.
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Affiliation(s)
| | - Anirban Mondal
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Paul W M Blom
- Max Planck Institute for Polymer Research, Mainz, Germany
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52
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Yaron DJ, Kowalewski T. Beware the nanovoids. NATURE MATERIALS 2019; 18:1154-1155. [PMID: 31548632 DOI: 10.1038/s41563-019-0502-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Affiliation(s)
- David J Yaron
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA.
| | - Tomasz Kowalewski
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
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53
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Ball ML, Zhang B, Fu T, Schattman AM, Paley DW, Ng F, Venkataraman L, Nuckolls C, Steigerwald ML. The importance of intramolecular conductivity in three dimensional molecular solids. Chem Sci 2019; 10:9339-9344. [PMID: 32110297 PMCID: PMC7006630 DOI: 10.1039/c9sc03144h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 08/20/2019] [Indexed: 12/26/2022] Open
Abstract
Recent years have seen tremendous progress towards understanding the relation between the molecular structure and function of organic field effect transistors. The metrics for organic field effect transistors, which are characterized by mobility and the on/off ratio, are known to be enhanced when the intermolecular interaction is strong and the intramolecular reorganization energy is low. While these requirements are adequate when describing organic field effect transistors with simple and planar aromatic molecular components, they are insufficient for complex building blocks, which have the potential to localize a carrier on the molecule. Here, we show that intramolecular conductivity can play a role in controlling device characteristics of organic field effect transistors made with macrocycle building blocks. We use two isomeric macrocyclic semiconductors that consist of perylene diimides linked with bithiophenes and find that the trans-linked macrocycle has a higher mobility than the cis-based device. Through a combination of single molecule junction conductance measurements of the components of the macrocycles, control experiments with acyclic counterparts to the macrocycles, and analyses of each of the materials using spectroscopy, electrochemistry, and density functional theory, we attribute the difference in electron mobility of the OFETs created with the two isomers to the difference in intramolecular conductivity of the two macrocycles.
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Affiliation(s)
- Melissa L Ball
- Department of Chemistry , Columbia University , New York , New York 10027 , USA . ; ;
| | - Boyuan Zhang
- Department of Chemistry , Columbia University , New York , New York 10027 , USA . ; ;
| | - Tianren Fu
- Department of Chemistry , Columbia University , New York , New York 10027 , USA . ; ;
- Department of Applied Physics and Applied Math , Columbia University , New York , New York 10027 , USA
| | - Ayden M Schattman
- Department of Chemistry , Columbia University , New York , New York 10027 , USA . ; ;
| | - Daniel W Paley
- Department of Chemistry , Columbia University , New York , New York 10027 , USA . ; ;
| | - Fay Ng
- Department of Chemistry , Columbia University , New York , New York 10027 , USA . ; ;
| | - Latha Venkataraman
- Department of Chemistry , Columbia University , New York , New York 10027 , USA . ; ;
- Department of Applied Physics and Applied Math , Columbia University , New York , New York 10027 , USA
| | - Colin Nuckolls
- Department of Chemistry , Columbia University , New York , New York 10027 , USA . ; ;
| | - Michael L Steigerwald
- Department of Chemistry , Columbia University , New York , New York 10027 , USA . ; ;
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54
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Tang CG, Syafiqah MN, Koh QM, Zhao C, Zaini J, Seah QJ, Cass MJ, Humphries MJ, Grizzi I, Burroughes JH, Png RQ, Chua LL, Ho PKH. Multivalent anions as universal latent electron donors. Nature 2019; 573:519-525. [PMID: 31554981 DOI: 10.1038/s41586-019-1575-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 07/08/2019] [Indexed: 11/09/2022]
Abstract
Electrodes with low work functions are required to efficiently inject electrons into semiconductor devices. However, when the work function drops below about 4 electronvolts, the electrode suffers oxidation in air, which prevents its fabrication in ambient conditions. Here we show that multivalent anions such as oxalate, carbonate and sulfite can act as powerful latent electron donors when dispersed as small ion clusters in a matrix, while retaining their ability to be processed in solution in ambient conditions. The anions in these clusters can even n-dope the semiconductor core of π-conjugated polyelectrolytes that have low electron affinities, through a ground-state doping mechanism that is further amplified by a hole-sensitized or photosensitized mechanism in the device. A theoretical analysis of donor levels of these anions reveals that they are favourably upshifted from ionic lattices by a decrease in the Coulomb stabilization of small ion clusters, and by irreversibility effects. We attain an ultralow effective work function of 2.4 electronvolts with the polyfluorene core. We realize high-performance, solution-processed, white-light-emitting diodes and organic solar cells using polymer electron injection layers with these universal anion donors, demonstrating a general approach to chemically designed and ambient-processed Ohmic electron contacts for semiconductor devices.
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Affiliation(s)
- Cindy G Tang
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Mazlan Nur Syafiqah
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Qi-Mian Koh
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Chao Zhao
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Jamal Zaini
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Qiu-Jing Seah
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | | | | | - Ilaria Grizzi
- Cambridge Display Technology Limited, Godmanchester, UK
| | | | - Rui-Qi Png
- Department of Physics, National University of Singapore, Singapore, Singapore.
| | - Lay-Lay Chua
- Department of Physics, National University of Singapore, Singapore, Singapore. .,Department of Chemistry, National University of Singapore, Singapore, Singapore.
| | - Peter K H Ho
- Department of Physics, National University of Singapore, Singapore, Singapore
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55
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Schroot R, Jäger M, Schubert US. Accumulative Charging of Redox-Active Side-Chain-Modified Polymers: Experimental and Computational Insights from Oligo- to Polymeric Triarylamines. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b00933] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Robert Schroot
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstraße 10, 07743 Jena, Germany
| | - Michael Jäger
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstraße 10, 07743 Jena, Germany
- Center for Energy and Environmental Chemistry Jena (CEEC Jena), Friedrich Schiller University Jena, Philosophenweg 7a, 07743 Jena, Germany
| | - Ulrich S. Schubert
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstraße 10, 07743 Jena, Germany
- Center for Energy and Environmental Chemistry Jena (CEEC Jena), Friedrich Schiller University Jena, Philosophenweg 7a, 07743 Jena, Germany
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56
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Short contacts between chains enhancing luminescence quantum yields and carrier mobilities in conjugated copolymers. Nat Commun 2019; 10:2614. [PMID: 31197152 PMCID: PMC6565747 DOI: 10.1038/s41467-019-10277-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 04/25/2019] [Indexed: 11/28/2022] Open
Abstract
Efficient conjugated polymer optoelectronic devices benefit from concomitantly high luminescence and high charge carrier mobility. This is difficult to achieve, as interchain interactions, which are needed to ensure efficient charge transport, tend also to reduce radiative recombination and lead to solid-state quenching effects. Many studies detail strategies for reducing these interactions to increase luminescence, or modifying chain packing motifs to improve percolation charge transport; however achieving these properties together has proved elusive. Here, we show that properly designed amorphous donor-alt-acceptor conjugated polymers can circumvent this problem; combining a tuneable energy gap, fast radiative recombination rates and luminescence quantum efficiencies >15% with high carrier mobilities exceeding 2.4 cm2/Vs. We use photoluminescence from exciton states pinned to close-crossing points to study the interplay between mobility and luminescence. These materials show promise towards realising advanced optoelectronic devices based on conjugated polymers, including electrically-driven polymer lasers. Designing conjugated polymers with high charge carrier mobility and fluorescence quantum efficiency, though attractive for optoelectronics, remains challenging. Here, the authors report a strategy for designing donor-acceptor copolymers whose optoelectronic properties exceed the state-of-the-art.
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57
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Zuo G, Linares M, Upreti T, Kemerink M. General rule for the energy of water-induced traps in organic semiconductors. NATURE MATERIALS 2019; 18:588-593. [PMID: 31011215 DOI: 10.1038/s41563-019-0347-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 03/18/2019] [Indexed: 05/19/2023]
Abstract
Charge carrier traps are generally highly detrimental for the performance of semiconductor devices. Unlike the situation for inorganic semiconductors, detailed knowledge about the characteristics and causes of traps in organic semiconductors is still very limited. Here, we accurately determine hole and electron trap energies for a wide range of organic semiconductors in thin-film form. We find that electron and hole trap energies follow a similar empirical rule and lie ~0.3-0.4 eV above the highest occupied molecular orbital and below the lowest unoccupied molecular orbital, respectively. Combining experimental and theoretical methods, the origin of the traps is shown to be a dielectric effect of water penetrating nanovoids in the organic semiconductor thin film. We also propose a solvent-annealing method to remove water-related traps from the materials investigated, irrespective of their energy levels. These findings represent a step towards the realization of trap-free organic semiconductor thin films.
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Affiliation(s)
- Guangzheng Zuo
- Complex Materials and Devices, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden
| | - Mathieu Linares
- Laboratory of Organic Electronics, ITN, Linkoping University, Linköping, Sweden
- Scientific Visualization Group, ITN, Linköping University, Linköping, Sweden
- Swedish e-Science Research Centre (SeRC), Linköping University, Linköping, Sweden
| | - Tanvi Upreti
- Complex Materials and Devices, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden
| | - Martijn Kemerink
- Complex Materials and Devices, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
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58
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Strunk KP, Abdulkarim A, Beck S, Marszalek T, Bernhardt J, Koser S, Pisula W, Jänsch D, Freudenberg J, Pucci A, Bunz UHF, Melzer C, Müllen K. Pristine Poly( para-phenylene): Relating Semiconducting Behavior to Kinetics of Precursor Conversion. ACS APPLIED MATERIALS & INTERFACES 2019; 11:19481-19488. [PMID: 31050397 PMCID: PMC6750640 DOI: 10.1021/acsami.9b03291] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 05/03/2019] [Indexed: 06/09/2023]
Abstract
We investigated unsubstituted poly( para-phenylene) (PPP), a long-desired prototype of a conjugated polymer semiconductor. PPP was accessed via thermal aromatization of a precursor polymer bearing kinked, solubility-inducing dimethoxycyclohexadienylene moieties. IR spectroscopy and Vis ellipsometry studies revealed that the rate of conversion of the precursor to PPP increases with temperature and decreases with film density, indicating a process with high activation volume. The obtained PPP films were analyzed in thin-film transistors to gain insights into the interplay between the degree of conversion and the resulting p-type semiconducting properties. The semiconducting behavior of PPP was further unambiguously proven through IR and transistor measurements of molybdenum trioxide p-doped films.
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Affiliation(s)
- Karl-Philipp Strunk
- Kirchhoff-Institut
für Physik, Ruprecht-Karls-Universität
Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
- Centre for Advanced
Materials, Ruprecht-Karls-Universität
Heidelberg, Im Neuenheimer Feld 225, 69120 Heidelberg, Germany
| | - Ali Abdulkarim
- InnovationLab, Speyerer Straße 4, 69115 Heidelberg, Germany
- Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Sebastian Beck
- Kirchhoff-Institut
für Physik, Ruprecht-Karls-Universität
Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
- InnovationLab, Speyerer Straße 4, 69115 Heidelberg, Germany
| | - Tomasz Marszalek
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Jakob Bernhardt
- Kirchhoff-Institut
für Physik, Ruprecht-Karls-Universität
Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
- InnovationLab, Speyerer Straße 4, 69115 Heidelberg, Germany
| | - Silke Koser
- Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Wojciech Pisula
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Daniel Jänsch
- InnovationLab, Speyerer Straße 4, 69115 Heidelberg, Germany
- Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Jan Freudenberg
- InnovationLab, Speyerer Straße 4, 69115 Heidelberg, Germany
- Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Annemarie Pucci
- Kirchhoff-Institut
für Physik, Ruprecht-Karls-Universität
Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
- Centre for Advanced
Materials, Ruprecht-Karls-Universität
Heidelberg, Im Neuenheimer Feld 225, 69120 Heidelberg, Germany
- InnovationLab, Speyerer Straße 4, 69115 Heidelberg, Germany
| | - Uwe H. F. Bunz
- InnovationLab, Speyerer Straße 4, 69115 Heidelberg, Germany
- Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Christian Melzer
- Kirchhoff-Institut
für Physik, Ruprecht-Karls-Universität
Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
- Centre for Advanced
Materials, Ruprecht-Karls-Universität
Heidelberg, Im Neuenheimer Feld 225, 69120 Heidelberg, Germany
- InnovationLab, Speyerer Straße 4, 69115 Heidelberg, Germany
| | - Klaus Müllen
- InnovationLab, Speyerer Straße 4, 69115 Heidelberg, Germany
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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59
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Bathula C, Mallikarjuna K, Kadam A, Shrestha NK, Khadtare S, Mane SD, Kim H. Synthesis and photophysical investigations of pyromellitic diimide based small molecules. INORG CHEM COMMUN 2019. [DOI: 10.1016/j.inoche.2019.02.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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60
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Goel M, Heinrich CD, Krauss G, Thelakkat M. Principles of Structural Design of Conjugated Polymers Showing Excellent Charge Transport toward Thermoelectrics and Bioelectronics Applications. Macromol Rapid Commun 2019; 40:e1800915. [DOI: 10.1002/marc.201800915] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 02/21/2019] [Indexed: 01/01/2023]
Affiliation(s)
- Mahima Goel
- Applied Functional PolymersMacromolecular Chemistry IUniversity of Bayreuth Universitätsstr. 30 Bayreuth 95440 Germany
| | - C. David Heinrich
- Applied Functional PolymersMacromolecular Chemistry IUniversity of Bayreuth Universitätsstr. 30 Bayreuth 95440 Germany
| | - Gert Krauss
- Applied Functional PolymersMacromolecular Chemistry IUniversity of Bayreuth Universitätsstr. 30 Bayreuth 95440 Germany
| | - Mukundan Thelakkat
- Applied Functional PolymersMacromolecular Chemistry IUniversity of Bayreuth Universitätsstr. 30 Bayreuth 95440 Germany
- Bavarian Polymer Institute (BPI)University of Bayreuth Universitätsstr. 30 Bayreuth 95440 Germany
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61
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Wang H, Huang J, Uddin MA, Liu B, Chen P, Shi S, Tang Y, Xing G, Zhang S, Woo HY, Guo H, Guo X. Cyano-Substituted Head-to-Head Polythiophenes: Enabling High-Performance n-Type Organic Thin-Film Transistors. ACS APPLIED MATERIALS & INTERFACES 2019; 11:10089-10098. [PMID: 30777429 DOI: 10.1021/acsami.8b22457] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Polythiophenes, built on the electron-rich thiophene unit, typically possess high-lying energy levels of the lowest unoccupied molecular orbitals (LUMOs) and show hole-transporting properties. In this study, we develop a series of n-type polythiophenes, P1-P3, based on head-to-head-linked 3,3'-dialkoxy-4,4'-dicyano-2,2'-bithiophene (BTCNOR) with distinct side chains. The BTCNOR unit shows not only highly planar backbone conformation enabled by the intramolecular noncovalent sulfur-oxygen interaction but also significantly suppressed LUMO level attributed to the cyano-substitution. Hence, all BTCNOR-based polymer semiconductors exhibit low-lying LUMO levels, which are ∼1.0 eV lower than that of regioregular poly(3-hexylthiophene) (rr-P3HT), a benchmark p-type polymer semiconductor. Consequently, all of the three polymers can enable unipolar n-type transport characteristics in organic thin-film transistors (OTFTs) with low off-currents ( Ioffs) of 10-10-10-11 A and large current on/off ratios ( Ion/ Ioffs) at the level of 106. Among them, polymer P2 with a 2-ethylhexyl side chain offers the highest film ordering, leading to the best device performance with an excellent electron mobility (μe) of 0.31 cm2 V-1 s-1 in off-center spin-cast OTFTs. To the best of our knowledge, this is the first report of n-type polythiophenes with electron mobility comparable to the hole mobility of the benchmark p-type rr-P3HT and approaching the electron mobility of the most-studied n-type polymer, poly(naphthalene diimide- alt-bithiophene) (i.e., N2200). The change of charge carrier polarity from p-type (rr-P3HT) to n-type (P2) with comparable mobility demonstrates the obvious effectiveness of our structural modification. Adoption of n-hexadecyl (P1) and 2-butyloctyl (P3) side chains leads to reduced film ordering and results in 1-2 orders of magnitude lower μes, showing the critical role of side chains in optimizing device performance. This study demonstrates the unique structural features of head-to-head linkage containing BTCNOR for constructing high-performance n-type polymers, i.e., the alkoxy chain for backbone conformation locking and providing polymer solubility as well as the strong electron-withdrawing cyano group for lowering LUMO levels and enabling n-type performance. The design strategy of BTCNOR-based polymers provides useful guidelines for developing n-type polythiophenes.
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Affiliation(s)
- Hang Wang
- Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM) , Nanjing Tech University , 30 South Puzhu Road , Nanjing 211816 , Jiangsu , China
- Department of Materials Science and Engineering, The Shenzhen Key Laboratory for Printed Organic Electronics , Southern University of Science and Technology (SUSTech) , No. 1088, Xueyuan Road , Shenzhen 518055 , Guangdong , China
| | - Jun Huang
- Department of Materials Science and Engineering, The Shenzhen Key Laboratory for Printed Organic Electronics , Southern University of Science and Technology (SUSTech) , No. 1088, Xueyuan Road , Shenzhen 518055 , Guangdong , China
- Center for Advanced Low-Dimension Materials, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials , Donghua University , Shanghai 201620 , China
| | - Mohammad Afsar Uddin
- Research Institute for Natural Sciences, Department of Chemistry , Korea University , Seoul 136-713 , South Korea
| | - Bin Liu
- Department of Materials Science and Engineering, The Shenzhen Key Laboratory for Printed Organic Electronics , Southern University of Science and Technology (SUSTech) , No. 1088, Xueyuan Road , Shenzhen 518055 , Guangdong , China
| | - Peng Chen
- Department of Materials Science and Engineering, The Shenzhen Key Laboratory for Printed Organic Electronics , Southern University of Science and Technology (SUSTech) , No. 1088, Xueyuan Road , Shenzhen 518055 , Guangdong , China
| | - Shengbin Shi
- Department of Materials Science and Engineering, The Shenzhen Key Laboratory for Printed Organic Electronics , Southern University of Science and Technology (SUSTech) , No. 1088, Xueyuan Road , Shenzhen 518055 , Guangdong , China
| | - Yumin Tang
- Department of Materials Science and Engineering, The Shenzhen Key Laboratory for Printed Organic Electronics , Southern University of Science and Technology (SUSTech) , No. 1088, Xueyuan Road , Shenzhen 518055 , Guangdong , China
| | - Guichuan Xing
- Institute of Applied Physics and Materials Engineering , University of Macau , Macao 999078 , China
| | - Shiming Zhang
- Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM) , Nanjing Tech University , 30 South Puzhu Road , Nanjing 211816 , Jiangsu , China
| | - Han Young Woo
- Research Institute for Natural Sciences, Department of Chemistry , Korea University , Seoul 136-713 , South Korea
| | - Han Guo
- Department of Materials Science and Engineering, The Shenzhen Key Laboratory for Printed Organic Electronics , Southern University of Science and Technology (SUSTech) , No. 1088, Xueyuan Road , Shenzhen 518055 , Guangdong , China
| | - Xugang Guo
- Department of Materials Science and Engineering, The Shenzhen Key Laboratory for Printed Organic Electronics , Southern University of Science and Technology (SUSTech) , No. 1088, Xueyuan Road , Shenzhen 518055 , Guangdong , China
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Liao K, Collins SD, Brus VV, Mikhnenko OV, Hu Y, Phan H, Nguyen TQ. n-Type Ionic-Organic Electronic Ratchets for Energy Harvesting. ACS APPLIED MATERIALS & INTERFACES 2019; 11:1081-1087. [PMID: 30480989 DOI: 10.1021/acsami.8b15042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Ionic-organic ratchets are three-terminal electronic devices with asymmetric conductivity of the active layer. These devices are capable of generating useful direct current electrical power by converting electromagnetic noise signals available in any environment. In this work, we demonstrate for the first time an n-type ionic-organic ratchet which can generate a current of up to 7.29 μA and power up to 12.5 μW that exceed the values reported for many of the presently state-of-the-art, p-type organic electronic ratchets. We show that n-type ratchets require elimination of electron traps at the SiO2 surface, which is not required in p-type devices. This can be achieved by using a trap-free passivation layer such as benzocyclobutene, where the traditional silane treatment is insufficient. Chemical doping is employed to further fill electron traps in the channel and increase carrier concentration and mobilities. Scanning Kelvin probe force microscopy studies provide evidence of a pn-like rectifying junction in the n-type ratchets fabricated in this work, which inherently differs from the rectification mechanism of previous ionic-organic p-type ratchets.
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Affiliation(s)
- Kenneth Liao
- Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry , University of California at Santa Barbara , Santa Barbara , California 93106 , United States
| | - Samuel D Collins
- Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry , University of California at Santa Barbara , Santa Barbara , California 93106 , United States
| | - Viktor V Brus
- Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry , University of California at Santa Barbara , Santa Barbara , California 93106 , United States
| | - Oleksandr V Mikhnenko
- Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry , University of California at Santa Barbara , Santa Barbara , California 93106 , United States
| | - Yuanyuan Hu
- Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry , University of California at Santa Barbara , Santa Barbara , California 93106 , United States
| | - Hung Phan
- Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry , University of California at Santa Barbara , Santa Barbara , California 93106 , United States
| | - Thuc-Quyen Nguyen
- Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry , University of California at Santa Barbara , Santa Barbara , California 93106 , United States
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Rana D, Donfack P, Jovanov V, Wagner V, Materny A. Ultrafast polaron-pair dynamics in a poly(3-hexylthiophene-2,5-diyl) device influenced by a static electric field: insights into electric-field-related charge loss. Phys Chem Chem Phys 2019; 21:21236-21248. [DOI: 10.1039/c9cp03736e] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Photogenerated polaron-pair ultrafast dynamics in poly(3-hexylthiophene)-based devices are found to be influenced by external electric fields via delayed field-induced singlet exciton dissociation, yielding a bimolecular decay contribution.
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Affiliation(s)
- Debkumar Rana
- Physics and Earth Sciences, Jacobs University Bremen
- 28759 Bremen
- Germany
| | - Patrice Donfack
- Physics and Earth Sciences, Jacobs University Bremen
- 28759 Bremen
- Germany
| | - Vladislav Jovanov
- Physics and Earth Sciences, Jacobs University Bremen
- 28759 Bremen
- Germany
| | - Veit Wagner
- Physics and Earth Sciences, Jacobs University Bremen
- 28759 Bremen
- Germany
| | - Arnulf Materny
- Physics and Earth Sciences, Jacobs University Bremen
- 28759 Bremen
- Germany
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Kettner M, Zhou M, Brill J, Blom PWM, Weitz RT. Complete Suppression of Bias-Induced Threshold Voltage Shift below 273 K in Solution-Processed High-Performance Organic Transistors. ACS APPLIED MATERIALS & INTERFACES 2018; 10:35449-35454. [PMID: 30251831 DOI: 10.1021/acsami.8b13035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Despite their importance for future applications, the operational electrical stability of organic thin-film transistors is far from being understood. Even in the most stable organic field-effect transistors (OFETs) operated under vacuum, a hitherto unknown source leads to bias stress. Here, we investigate the electrical characteristics and operational stability of a high-performance diketopyrrolopyrrole- alt-terthiophene organic semiconductor. Even though the OFETs are characterized by a high mobility of 3 cm2 V-1 s-1 and trap-free transport, the threshold voltage shift in all stress modes remains sensitive to the presence of water even when operating devices in high vacuum. Exponential fitting from current bias-stress measurement up to 500 000 s showed a bias-voltage shift of <1 V, which corresponds to the density of the bias-induced trap states at infinite time NT∞ = 7.6 × 1010 cm-2. We have surprisingly found that electrical stress could be completely suppressed when devices are cooled to below 273 K. We present evidence that H3O+ and OH- stemming from the autoionization of liquid water is the hitherto unidentified universal trap (i.e., an extrinsic trap not stemming from the semiconductor itself) causing threshold voltage shift even in the otherwise stable devices. This interpretation would also clarify why in the literature similar NT have been reported in various semiconductors, suggesting that this number is independent of the organic semiconductor, processing and measurement environment but only dependent on residual contaminants-most notably water.
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Affiliation(s)
- Michel Kettner
- BASF SE, FET Systems , Carl-Bosch-Straße 38 , 67056 Ludwigshafen , Germany
- InnovationLab GmbH , Speyerer Str. 4 , 69115 Heidelberg , Germany
| | - Mi Zhou
- BASF SE, FET Systems , Carl-Bosch-Straße 38 , 67056 Ludwigshafen , Germany
- InnovationLab GmbH , Speyerer Str. 4 , 69115 Heidelberg , Germany
| | - Jochen Brill
- BASF SE, FET Systems , Carl-Bosch-Straße 38 , 67056 Ludwigshafen , Germany
- InnovationLab GmbH , Speyerer Str. 4 , 69115 Heidelberg , Germany
| | - Paul W M Blom
- Max-Planck-Institute for Polymer Research , Ackermannweg 10 , 55128 Mainz , Germany
| | - R Thomas Weitz
- Physics of Nanosystems, Faculty of Physics , Ludwig-Maximilians University , Amalienstr. 54 , 80799 Munich , Germany
- Center for Nanoscience (CeNS) , Ludwig-Maximilians University Munich , Schellingstr. 4 , 80799 Munich , Germany
- Nanosystems Initiative Munich (NIM) , Schellingstr. 4 , 80799 Munich , Germany
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65
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Kranthiraja K, Long DX, Sree VG, Cho W, Cho YR, Zaheer A, Lee JC, Noh YY, Jin SH. Sequential Fluorination on Napthaleneamide-Based Conjugated Polymers and Their Impact on Charge Transport Properties. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b00748] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Kakaraparthi Kranthiraja
- Department of Chemistry Education, Graduate Department of Chemical Materials, Institute for Plastic Information and Energy Materials, Pusan National University, Busan, 46241, Republic of Korea
| | - Dang Xuan Long
- Department of Energy and Materials Engineering, Dongguk University, 30 Pildong-ro, 1 gil, Jung-gu, Seoul 04620, Republic of Korea
| | - Vijaya Gopalan Sree
- Department of Chemistry Education, Graduate Department of Chemical Materials, Institute for Plastic Information and Energy Materials, Pusan National University, Busan, 46241, Republic of Korea
| | - Woosum Cho
- Department of Chemistry Education, Graduate Department of Chemical Materials, Institute for Plastic Information and Energy Materials, Pusan National University, Busan, 46241, Republic of Korea
| | - Young-Rae Cho
- Division of Materials Science and Engineering, Pusan National University, Busandaehak-ro 63-2, Busan 46241, Republic of Korea
| | - Abbas Zaheer
- Advanced Materials Division, Korea Research Institute of Chemical Technology (KRICT), Daejeon 34114, Republic of Korea
- Advanced Materials and Chemical Engineering, University of Science and Technology(UST), Daejeon 34113, Republic of Korea
| | - Jong-Cheol Lee
- Advanced Materials Division, Korea Research Institute of Chemical Technology (KRICT), Daejeon 34114, Republic of Korea
- Advanced Materials and Chemical Engineering, University of Science and Technology(UST), Daejeon 34113, Republic of Korea
| | - Yong-Young Noh
- Department of Energy and Materials Engineering, Dongguk University, 30 Pildong-ro, 1 gil, Jung-gu, Seoul 04620, Republic of Korea
| | - Sung-Ho Jin
- Department of Chemistry Education, Graduate Department of Chemical Materials, Institute for Plastic Information and Energy Materials, Pusan National University, Busan, 46241, Republic of Korea
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66
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Yang M, Cho D, Kim J, Shin N, Shekhar S, Hong S. Nanoscale "Noise-Source Switching" during the Optoelectronic Switching of Phase-Separated Polymer Nanocomposites. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1800885. [PMID: 29806136 DOI: 10.1002/smll.201800885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 04/13/2018] [Indexed: 06/08/2023]
Abstract
A method is developed to directly map nanoscale "noise-source switching" phenomena during the optoelectronic switching of phase-separated polymer nanocomposites of tetrathiafulvalene (TTF) and phenyl-C61 -butyric acid methyl ester (PCBM) molecules dispersed in a polystyrene (PS) matrix. In the method, electrical current and noise maps of the nanocomposite film are recorded using a conducting nanoprobe, enabling the mapping of a conductivity and a noise-source density. The results provide evidence for a repeated modulation in noise sources, a "noise-source switching," in each stage of a switching cycle. Interestingly, when the nanocomposite is "set" by a high bias, insulating PS-rich phases shows a drastic decrease in a noise-source density which becomes lower than that of conducting TTF-PCBM-rich phases. This can be attributed to a trap filling by charge carriers generated from a TTF (donor)-PCBM (acceptor) complex. In addition, when the film is exposed to UV, an optical switching occurs due to chemical reactions which lead to irreversible changes on the noise-source density and conductivity. The method provides a new insight on noise-source activities during the optoelectronic switching of polymer nanocomposites and thus can be a powerful tool for basic noise research and applications in organic memory devices.
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Affiliation(s)
- Myungjae Yang
- Department of Physics and Astronomy, Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
| | - Duckhyung Cho
- Department of Physics and Astronomy, Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
| | - Jeongsu Kim
- Department of Physics and Astronomy, Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
| | - Narae Shin
- Department of Physics and Astronomy, Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
| | - Shashank Shekhar
- Department of Physics and Astronomy, Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
| | - Seunghun Hong
- Department of Physics and Astronomy, Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
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67
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Shekhar S, Cho D, Cho DG, Yang M, Hong S. Mapping nanoscale effects of localized noise-source activities on photoconductive charge transports in polymer-blend films. NANOTECHNOLOGY 2018; 29:205204. [PMID: 29488470 DOI: 10.1088/1361-6528/aab2dd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We develolped a method to directly image the nanoscale effects of localized noise-source activities on photoconducting charge transports in domain structures of phase-separated polymer-blend films of Poly(9,9-di-n-octylfluorenyl-2,7-diyl) and Poly(9,9-di-n-octylfluorene-alt-benzothiadiazole). For the imaging, current and noise maps of the polymer-blend were recorded using a conducting nanoprobe in contact with the surface, enabling the conductivity (σ) and noise-source density (N T) mappings under an external stimulus. The blend-films exhibited the phase-separation between the constituent polymers at domains level. Within a domain, high σ (low N T) and low σ (high N T) regions were observed, which could be associated with the ordered and disordered regions of a domain. In the N T maps, we observed that noise-sources strongly affected the conduction mechanism, resulting in a scaling behavior of σ ∝ [Formula: see text] in both ordered and disordered regions. When a blend film was under an influence of an external stimulus such as a high bias or an illumination, an increase in the σ was observed, but that also resulted in increases in the N T as a trade-off. Interestingly, the Δσ versus ΔN T plot exhibited an unusual scaling behavior of Δσ ∝ [Formula: see text] which is attributed to the de-trapping of carriers from deep traps by the external stimuli. In addition, we found that an external stimulus increased the conductivity at the interfaces without significantly increasing their N T, which can be the origin of the superior performances of polymer-blend based devices. These results provide valuable insight about the effects of noise-sources on nanoscale optoelectronic properties in polymer-blend films, which can be an important guideline for improving devices based on polymer-blend.
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68
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Pandey P, Kunwar S, Sui M, Bastola S, Lee J. Modulation of Morphology and Optical Property of Multi-Metallic PdAuAg and PdAg Alloy Nanostructures. NANOSCALE RESEARCH LETTERS 2018; 13:151. [PMID: 29767305 PMCID: PMC5955875 DOI: 10.1186/s11671-018-2551-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 04/23/2018] [Indexed: 06/08/2023]
Abstract
In this work, the evolution of PdAg and PdAuAg alloy nanostructures is demonstrated on sapphire (0001) via the solid-state dewetting of multi-metallic thin films. Various surface configurations, size, and arrangements of bi- and tri-metallic alloy nanostructures are fabricated as a function of annealing temperature, annealing duration, film thickness, and deposition arrangements such as bi-layers (Pd/Ag), tri-layers (Pd/Au/Ag), and multi-layers (Pd/Au/Ag × 5). Specifically, the tri-layers film shows the gradual evolution of over-grown NPs, voids, wiggly nanostructures, and isolated PdAuAg alloy nanoparticles (NPs) along with the increased annealing temperature. In contrast, the multi-layers film with same thickness show the enhanced dewetting rate, which results in the formation of voids at relatively lower temperature, wider spacing, and structural regularity of alloy NPs at higher temperature. The dewetting enhancement is attributed to the increased number of interfaces and reduced individual layer thickness, which aid the inter-diffusion process at the initial stage. In addition, the time evolution of the Pd150 nm/Ag80 nm bi-layer films at constant temperature show the wiggly-connected and isolated PdAg alloy NPs. The overall evolution of alloy NPs is discussed based on the solid-state dewetting mechanism in conjunction with the diffusion, inter-diffusion, alloying, sublimation, Rayleigh instability, and surface energy minimization. Depending upon their surface morphologies, the bi- and tri-metallic alloy nanostructures exhibit the dynamic reflectance spectra, which show the formation of dipolar (above 700 nm) and quadrupolar resonance peaks (~ 380 nm) and wide dips in the visible region as correlated to the localized surface plasmon resonance (LSPR) effect. An absorption dip is readily shifted from ~ 510 to ~ 475 nm along with the decreased average size of alloy nanostructures.
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Affiliation(s)
- Puran Pandey
- College of Electronics and Information, Kwangwoon University, Nowon-gu, Seoul, 139-701 South Korea
| | - Sundar Kunwar
- College of Electronics and Information, Kwangwoon University, Nowon-gu, Seoul, 139-701 South Korea
| | - Mao Sui
- College of Electronics and Information, Kwangwoon University, Nowon-gu, Seoul, 139-701 South Korea
| | - Sushil Bastola
- College of Electronics and Information, Kwangwoon University, Nowon-gu, Seoul, 139-701 South Korea
| | - Jihoon Lee
- College of Electronics and Information, Kwangwoon University, Nowon-gu, Seoul, 139-701 South Korea
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69
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Röhr JA, Moia D, Haque SA, Kirchartz T, Nelson J. Exploring the validity and limitations of the Mott-Gurney law for charge-carrier mobility determination of semiconducting thin-films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:105901. [PMID: 29381142 DOI: 10.1088/1361-648x/aaabad] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Using drift-diffusion simulations, we investigate the voltage dependence of the dark current in single carrier devices typically used to determine charge-carrier mobilities. For both low and high voltages, the current increases linearly with the applied voltage. Whereas the linear current at low voltages is mainly due to space charge in the middle of the device, the linear current at high voltage is caused by charge-carrier saturation due to a high degree of injection. As a consequence, the current density at these voltages does not follow the classical square law derived by Mott and Gurney, and we show that for trap-free devices, only for intermediate voltages, a space-charge-limited drift current can be observed with a slope that approaches a value of two. We show that, depending on the thickness of the semiconductor layer and the size of the injection barriers, the two linear current-voltage regimes can dominate the whole voltage range, and the intermediate Mott-Gurney regime can shrink or disappear. In this case, which will especially occur for thicknesses and injection barriers typical of single-carrier devices used to probe organic semiconductors, a meaningful analysis using the Mott-Gurney law will become unachievable, because a square-law fit can no longer be achieved, resulting in the mobility being substantially underestimated. General criteria for when to expect deviations from the Mott-Gurney law when used for analysis of intrinsic semiconductors are discussed.
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Affiliation(s)
- Jason A Röhr
- Department of Physics and Centre for Plastic Electronics, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom. Department of Chemistry and Centre for Plastic Electronics, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
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70
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Bao Q, Liu X, Braun S, Yang J, Li Y, Tang J, Duan C, Fahlman M. The Effect of Oxygen Uptake on Charge Injection Barriers in Conjugated Polymer Films. ACS APPLIED MATERIALS & INTERFACES 2018; 10:6491-6497. [PMID: 29377664 DOI: 10.1021/acsami.7b17368] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The energy offset between the electrode Fermi level and organic semiconductor transport levels is a key parameter controlling the charge injection barrier and hence efficiency of organic electronic devices. Here, we systematically explore the effect of in situ oxygen exposure on energetics in n-type conjugated polymer P(NDI2OD-T2) films. The analysis reveals that an interfacial potential step is introduced for a series of P(NDI2OD-T2) electrode contacts, causing a nearly constant downshift of the vacuum level, while the ionization energies versus vacuum level remain constant. These findings are attributed to the establishment of a so-called double-dipole step via motion of charged molecules and will modify the charge injection barriers at electrode contact. We further demonstrate that the same behavior occurs when oxygen interacts with p-type polymer TQ1 films, indicating it is possible to be a universal effect for organic semiconductors.
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Affiliation(s)
- Qinye Bao
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University , 200241 Shanghai, P.R. China
- Division of Surface Physics and Chemistry, IFM, Linköping University , SE-58183 Linköping, Sweden
| | - Xianjie Liu
- Division of Surface Physics and Chemistry, IFM, Linköping University , SE-58183 Linköping, Sweden
| | - Slawomir Braun
- Division of Surface Physics and Chemistry, IFM, Linköping University , SE-58183 Linköping, Sweden
| | - Jianming Yang
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University , 200241 Shanghai, P.R. China
| | | | | | - Chungang Duan
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University , 200241 Shanghai, P.R. China
| | - Mats Fahlman
- Division of Surface Physics and Chemistry, IFM, Linköping University , SE-58183 Linköping, Sweden
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71
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Gong S, Zhu ZH, Li Z. Electron tunnelling and hopping effects on the temperature coefficient of resistance of carbon nanotube/polymer nanocomposites. Phys Chem Chem Phys 2018; 19:5113-5120. [PMID: 28138678 DOI: 10.1039/c6cp08115k] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Effectively tailoring the temperature coefficient of resistance (TCR) is critical for multifunctional carbon nanotube (CNT) polymer composites with sensing capability. By developing a new multiscale percolation network model, this work reveals theoretically that the zero-TCR could be achieved by adjusting competing contributions from thermally assisted tunnelling transport at CNT junctions and thermal expansion of matrices. On the other hand, the negative temperature coefficient of nanocomposites above glass transition temperature could be greatly enhanced because the transport mechanism at the CNT junctions experienced a transition from tunnelling to hopping. Both tube-tube and/or tube-matrix interactions at conjunction and the structural distortion of nanotubes are considered in the newly proposed model. To validate the model, CNT/polymer nanocomposites with nearly constant resistance values (zero-TCR) below the glass transition temperature and a high TCR (98% resistance change ratio) resulting from the glass transition of the polymer matrix are successfully developed. The study also suggests that the desired parameters to achieve the zero-TCR property and the potential resistance change ratio could be improved by the glass transition in nanocomposites. This could be beneficial for the development of high quality sensing materials.
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Affiliation(s)
- S Gong
- School of Metallurgy and Environment, Central South University, Changsha, 410083, People's Republic of China and School of Materials Science and Engineering, Central South University, Changsha, 410083, People's Republic of China and Department of Mechanical Engineering, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada.
| | - Z H Zhu
- Department of Mechanical Engineering, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada.
| | - Z Li
- School of Materials Science and Engineering, Central South University, Changsha, 410083, People's Republic of China
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72
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Fused electron deficient semiconducting polymers for air stable electron transport. Nat Commun 2018; 9:416. [PMID: 29379022 PMCID: PMC5789062 DOI: 10.1038/s41467-018-02852-6] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 01/03/2018] [Indexed: 12/13/2022] Open
Abstract
Conventional semiconducting polymer synthesis typically involves transition metal-mediated coupling reactions that link aromatic units with single bonds along the backbone. Rotation around these bonds contributes to conformational and energetic disorder and therefore potentially limits charge delocalisation, whereas the use of transition metals presents difficulties for sustainability and application in biological environments. Here we show that a simple aldol condensation reaction can prepare polymers where double bonds lock-in a rigid backbone conformation, thus eliminating free rotation along the conjugated backbone. This polymerisation route requires neither organometallic monomers nor transition metal catalysts and offers a reliable design strategy to facilitate delocalisation of frontier molecular orbitals, elimination of energetic disorder arising from rotational torsion and allowing closer interchain electronic coupling. These characteristics are desirable for high charge carrier mobilities. Our polymers with a high electron affinity display long wavelength NIR absorption with air stable electron transport in solution processed organic thin film transistors. Semiconducting polymers are usually prepared by transition metal mediated coupling reactions that cause problems for sustainability and biological applications. Here the authors synthesise fused electron deficient polymers that are air stable and have high electron affinities, via metal free aldol polymerisation reactions.
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73
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Zhou J, Bi S, Yang S, Zhou H, Zhang Y. Ambipolar charge transport in a bis-diketopyrrolopyrrole small molecule semiconductor with tunable energetic disorder. Phys Chem Chem Phys 2018; 20:1787-1793. [DOI: 10.1039/c7cp07708d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Energetic disorder and activation energy in ambipolar OFETs based on a small molecule BTDPP2 are tuned by its crystallinity.
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Affiliation(s)
- Jiyu Zhou
- HEEGER Beijing Research & Development Center, School of Chemistry, Beihang University
- Beijing 100191
- P. R. China
| | - Shiqing Bi
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology
- Beijing 100190
- P. R. China
| | - Shuo Yang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology
- Beijing 100190
- P. R. China
| | - Huiqiong Zhou
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology
- Beijing 100190
- P. R. China
| | - Yuan Zhang
- HEEGER Beijing Research & Development Center, School of Chemistry, Beihang University
- Beijing 100191
- P. R. China
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74
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Saiz F, Cubero D, Quirke N. The excess electron at polyethylene interfaces. Phys Chem Chem Phys 2018; 20:25186-25194. [DOI: 10.1039/c8cp01330f] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This work investigates the energy and spatial properties of excess electrons in polyethylene in bulk phases and, for the first time, at amorphous vacuum interfaces using a pseudopotential single-electron method (Lanczos diagonalisation) and density functional theory (DFT).
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Affiliation(s)
- Fernan Saiz
- Department of Chemistry
- Imperial College
- London
- UK
| | - David Cubero
- Departmento de Física Aplicada I
- Escuela Politécnica Superior
- Universidad de Sevilla
- Seville
- Spain
| | - Nick Quirke
- Department of Chemistry
- Imperial College
- London
- UK
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75
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Love JA, Feuerstein M, Wolff CM, Facchetti A, Neher D. Lead Halide Perovskites as Charge Generation Layers for Electron Mobility Measurement in Organic Semiconductors. ACS APPLIED MATERIALS & INTERFACES 2017; 9:42011-42019. [PMID: 29083145 DOI: 10.1021/acsami.7b10361] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Hybrid lead halide perovskites are introduced as charge generation layers (CGLs) for the accurate determination of electron mobilities in thin organic semiconductors. Such hybrid perovskites have become a widely studied photovoltaic material in their own right, for their high efficiencies, ease of processing from solution, strong absorption, and efficient photogeneration of charge. Time-of-flight (ToF) measurements on bilayer samples consisting of the perovskite CGL and an organic semiconductor layer of different thickness are shown to be determined by the carrier motion through the organic material, consistent with the much higher charge carrier mobility in the perovskite. Together with the efficient photon-to-electron conversion in the perovskite, this high mobility imbalance enables electron-only mobility measurement on relatively thin application-relevant organic films, which would not be possible with traditional ToF measurements. This architecture enables electron-selective mobility measurements in single components as well as bulk-heterojunction films as demonstrated in the prototypical polymer/fullerene blends. To further demonstrate the potential of this approach, electron mobilities were measured as a function of electric field and temperature in an only 127 nm thick layer of a prototypical electron-transporting perylene diimide-based polymer, and found to be consistent with an exponential trap distribution of ca. 60 meV. Our study furthermore highlights the importance of high mobility charge transporting layers when designing perovskite solar cells.
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Affiliation(s)
- John A Love
- Institute for Physics and Astronomy, University of Potsdam , Karl-Liebknecht-Straße 24-25, Potsdam-Golm 14476, Germany
| | - Markus Feuerstein
- Institute for Physics and Astronomy, University of Potsdam , Karl-Liebknecht-Straße 24-25, Potsdam-Golm 14476, Germany
| | - Christian M Wolff
- Institute for Physics and Astronomy, University of Potsdam , Karl-Liebknecht-Straße 24-25, Potsdam-Golm 14476, Germany
| | - Antonio Facchetti
- Department of Chemistry and The Materials Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Dieter Neher
- Institute for Physics and Astronomy, University of Potsdam , Karl-Liebknecht-Straße 24-25, Potsdam-Golm 14476, Germany
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76
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Kim MJ, Jung AR, Lee M, Kim D, Ro S, Jin SM, Nguyen HD, Yang J, Lee KK, Lee E, Kang MS, Kim H, Choi JH, Kim B, Cho JH. Structure-Property Relationships of Semiconducting Polymers for Flexible and Durable Polymer Field-Effect Transistors. ACS APPLIED MATERIALS & INTERFACES 2017; 9:40503-40515. [PMID: 29090568 DOI: 10.1021/acsami.7b12435] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report high-performance top-gate bottom-contact flexible polymer field-effect transistors (FETs) fabricated by flow-coating diketopyrrolopyrrole (DPP)-based and naphthalene diimide (NDI)-based polymers (P(DPP2DT-T2), P(DPP2DT-TT), P(DPP2DT-DTT), P(NDI2OD-T2), P(NDI2OD-F2T2), and P(NDI2OD-Se2)) as semiconducting channel materials. All of the polymers displayed good FET characteristics with on/off current ratios exceeding 107. The highest hole mobility of 1.51 cm2 V-1 s-1 and the highest electron mobility of 0.85 cm2 V-1 s-1 were obtained from the P(DPP2DT-T2) and P(NDI2OD-Se2) polymer FETs, respectively. The impacts of the polymer structures on the FET performance are well-explained by the interplay between the crystallinity, the tendency of the polymer backbone to adopt an edge-on orientation, and the interconnectivity of polymer fibrils in the film state. Additionally, we demonstrated that all of the flexible polymer-based FETs were highly resistant to tensile stress, with negligible changes in their carrier mobilities and on/off ratios after a bending test. Conclusively, these high-performance, flexible, and durable FETs demonstrate the potential of semiconducting conjugated polymers for use in flexible electronic applications.
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Affiliation(s)
- Min Je Kim
- SKKU Advanced Institute of Nanotechnology (SAINT), School of Chemical Engineering, Sungkyunkwan University , Suwon 16419, Republic of Korea
| | - A-Ra Jung
- Department of Science Education, Ewha Womans University , Seoul 03760, Republic of Korea
| | - Myeongjae Lee
- Department of Chemistry, Korea University , Seoul 02841, Republic of Korea
| | - Dongjin Kim
- Department of Physics, Sogang University , Seoul 121-742, Republic of Korea
| | - Suhee Ro
- Department of Science Education, Ewha Womans University , Seoul 03760, Republic of Korea
| | - Seon-Mi Jin
- Graduate School of Analytical Science and Technology, Chungnam National University , Daejeon 34134, Republic of Korea
| | - Hieu Dinh Nguyen
- Department of Chemistry, Kunsan National University , Kunsan-si 54150, Republic of Korea
| | - Jeehye Yang
- Department of Chemical Engineering, Soongsil University , Seoul 06978, Republic of Korea
| | - Kyung-Koo Lee
- Department of Chemistry, Kunsan National University , Kunsan-si 54150, Republic of Korea
| | - Eunji Lee
- Graduate School of Analytical Science and Technology, Chungnam National University , Daejeon 34134, Republic of Korea
| | - Moon Sung Kang
- Department of Chemical Engineering, Soongsil University , Seoul 06978, Republic of Korea
| | - Hyunjung Kim
- Department of Physics, Sogang University , Seoul 121-742, Republic of Korea
| | - Jong-Ho Choi
- Department of Chemistry, Korea University , Seoul 02841, Republic of Korea
| | - BongSoo Kim
- Department of Science Education, Ewha Womans University , Seoul 03760, Republic of Korea
| | - Jeong Ho Cho
- SKKU Advanced Institute of Nanotechnology (SAINT), School of Chemical Engineering, Sungkyunkwan University , Suwon 16419, Republic of Korea
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Jacobs IE, Moulé AJ. Controlling Molecular Doping in Organic Semiconductors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1703063. [PMID: 28921668 DOI: 10.1002/adma.201703063] [Citation(s) in RCA: 177] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 07/24/2017] [Indexed: 05/23/2023]
Abstract
The field of organic electronics thrives on the hope of enabling low-cost, solution-processed electronic devices with mechanical, optoelectronic, and chemical properties not available from inorganic semiconductors. A key to the success of these aspirations is the ability to controllably dope organic semiconductors with high spatial resolution. Here, recent progress in molecular doping of organic semiconductors is summarized, with an emphasis on solution-processed p-type doped polymeric semiconductors. Highlighted topics include how solution-processing techniques can control the distribution, diffusion, and density of dopants within the organic semiconductor, and, in turn, affect the electronic properties of the material. Research in these areas has recently intensified, thanks to advances in chemical synthesis, improved understanding of charged states in organic materials, and a focus on relating fabrication techniques to morphology. Significant disorder in these systems, along with complex interactions between doping and film morphology, is often responsible for charge trapping and low doping efficiency. However, the strong coupling between doping, solubility, and morphology can be harnessed to control crystallinity, create doping gradients, and pattern polymers. These breakthroughs suggest a role for molecular doping not only in device function but also in fabrication-applications beyond those directly analogous to inorganic doping.
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Affiliation(s)
- Ian E Jacobs
- Department of Materials Science, University of California, Davis, 1 Shields Avenue, Davis, CA, 95616, USA
| | - Adam J Moulé
- Department of Chemical Engineering, University of California, Davis, 1 Shields Avenue, Davis, CA, 95616, USA
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78
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Wagenpfahl A. Mobility dependent recombination models for organic solar cells. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:373001. [PMID: 28612756 DOI: 10.1088/1361-648x/aa7952] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Modern solar cell technologies are driven by the effort to enhance power conversion efficiencies. A main mechanism limiting power conversion efficiencies is charge carrier recombination which is a direct function of the encounter probability of both recombination partners. In inorganic solar cells with rather high charge carrier mobilities, charge carrier recombination is often dominated by energetic states which subsequently trap both recombination partners for recombination. Free charge carriers move fast enough for Coulomb attraction to be irrelevant for the encounter probability. Thus, charge carrier recombination is independent of charge carrier mobilities. In organic semiconductors charge carrier mobilities are much lower. Therefore, electrons and holes have more time react to mutual Coulomb-forces. This results in the strong charge carrier mobility dependencies of the observed charge carrier recombination rates. In 1903 Paul Langevin published a fundamental model to describe the recombination of ions in gas-phase or aqueous solutions, known today as Langevin recombination. During the last decades this model was used to interpret and model recombination in organic semiconductors. However, certain experiments especially with bulk-heterojunction solar cells reveal much lower recombination rates than predicted by Langevin. In search of an explanation, many material and device properties such as morphology and energetic properties have been examined in order to extend the validity of the Langevin model. A key argument for most of these extended models is, that electron and hole must find each other at a mutual spatial location. This encounter may be limited for instance by trapping of charges in trap states, by selective electrodes separating electrons and holes, or simply by the morphology of the involved semiconductors, making it impossible for electrons and holes to recombine at high rates. In this review, we discuss the development of mobility limited recombination models from the early Langevin theory to state-of-the art models for charge carrier recombination in organic solar cells.
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79
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Janasz L, Luczak A, Marszalek T, Dupont BGR, Jung J, Ulanski J, Pisula W. Balanced Ambipolar Organic Field-Effect Transistors by Polymer Preaggregation. ACS APPLIED MATERIALS & INTERFACES 2017; 9:20696-20703. [PMID: 28560870 DOI: 10.1021/acsami.7b03399] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Ambipolar organic field-effect transistors (OFETs) based on heterojunction active films still suffer from an imbalance in the transport of electrons and holes. This problem is related to an uncontrolled phase separation between the donor and acceptor organic semiconductors in the thin films. In this work, we have developed a concept to improve the phase separation in heterojunction transistors to enhance their ambipolar performance. This concept is based on preaggregation of the donor polymer, in this case poly(3-hexylthiophene) (P3HT), before solution mixing with the small-molecular-weight acceptor, phenyl-C61-butyric acid methyl ester (PCBM). The resulting heterojunction transistor morphology consists of self-assembled P3HT fibers embedded in a PCBM matrix, ensuring balanced mobilities reaching 0.01 cm2/V s for both holes and electrons. These are the highest mobility values reported so far for ambipolar OFETs based on P3HT/PCBM blends. Preaggregation of the conjugated polymer before fabricating binary blends can be regarded as a general concept for a wider range of semiconducting systems applicable in organic electronic devices.
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Affiliation(s)
- Lukasz Janasz
- Department of Molecular Physics, Faculty of Chemistry, Lodz University of Technology , Zeromskiego 116, 90-924 Lodz, Poland
| | - Adam Luczak
- Department of Molecular Physics, Faculty of Chemistry, Lodz University of Technology , Zeromskiego 116, 90-924 Lodz, Poland
| | - Tomasz Marszalek
- Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg , 69120 Heidelberg, Germany
- InnovationLab , Speyererstr. 4, 69115 Heidelberg, Germany
| | - Bertrand G R Dupont
- Department of Molecular Physics, Faculty of Chemistry, Lodz University of Technology , Zeromskiego 116, 90-924 Lodz, Poland
| | - Jaroslaw Jung
- Department of Molecular Physics, Faculty of Chemistry, Lodz University of Technology , Zeromskiego 116, 90-924 Lodz, Poland
| | - Jacek Ulanski
- Department of Molecular Physics, Faculty of Chemistry, Lodz University of Technology , Zeromskiego 116, 90-924 Lodz, Poland
| | - Wojciech Pisula
- Department of Molecular Physics, Faculty of Chemistry, Lodz University of Technology , Zeromskiego 116, 90-924 Lodz, Poland
- Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany
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80
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Röhr JA, Kirchartz T, Nelson J. On the correct interpretation of the low voltage regime in intrinsic single-carrier devices. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:205901. [PMID: 28294108 DOI: 10.1088/1361-648x/aa66cc] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
We discuss the approach of determining the charge-carrier density of a single-carrier device by combining Ohm's law and the Mott-Gurney law. We show that this approach is seldom valid, due to the fact that whenever Ohm's law is applicable the Mott-Gurney law is usually not, and vice versa. We do this using a numerical drift-diffusion solver to calculate the current density-voltage curves and the charge-carrier density, with increasing doping concentration. As this doping concentration is increased to very large values, using Ohm's law becomes a sensible way of measuring the product of mobility and doping density in the sample. However, in the high-doping limit, the current is no longer governed by space-charge and it will no longer be possible to determine the charge-carrier mobility using the Mott-Gurney law. This leaves the value for the mobility as an unknown in the mobility-doping density product in Ohm's law. We also show that, when the charge-carrier mobility for an intrinsic semiconductor is known in advance, the carrier density is underestimated up to many orders of magnitude if Ohm's law is used. We finally seek to establish a window of conditions where the two methods can be combined to yield reasonable results.
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Affiliation(s)
- Jason A Röhr
- Department of Physics and Centre for Plastic Electronics, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom. Department of Chemistry and Centre for Plastic Electronics, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom
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81
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Nikolka M, Nasrallah I, Rose B, Ravva MK, Broch K, Sadhanala A, Harkin D, Charmet J, Hurhangee M, Brown A, Illig S, Too P, Jongman J, McCulloch I, Bredas JL, Sirringhaus H. High operational and environmental stability of high-mobility conjugated polymer field-effect transistors through the use of molecular additives. NATURE MATERIALS 2017; 16:356-362. [PMID: 27941806 DOI: 10.1038/nmat4785] [Citation(s) in RCA: 141] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 09/23/2016] [Indexed: 05/22/2023]
Abstract
Due to their low-temperature processing properties and inherent mechanical flexibility, conjugated polymer field-effect transistors (FETs) are promising candidates for enabling flexible electronic circuits and displays. Much progress has been made on materials performance; however, there remain significant concerns about operational and environmental stability, particularly in the context of applications that require a very high level of threshold voltage stability, such as active-matrix addressing of organic light-emitting diode displays. Here, we investigate the physical mechanisms behind operational and environmental degradation of high-mobility, p-type polymer FETs and demonstrate an effective route to improve device stability. We show that water incorporated in nanometre-sized voids within the polymer microstructure is the key factor in charge trapping and device degradation. By inserting molecular additives that displace water from these voids, it is possible to increase the stability as well as uniformity to a high level sufficient for demanding industrial applications.
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Affiliation(s)
- Mark Nikolka
- Optoelectronics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Iyad Nasrallah
- Optoelectronics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Bradley Rose
- Solar &Photovoltaics Engineering Research Center, Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Mahesh Kumar Ravva
- Solar &Photovoltaics Engineering Research Center, Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Katharina Broch
- Optoelectronics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Aditya Sadhanala
- Optoelectronics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - David Harkin
- Optoelectronics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Jerome Charmet
- Department of Chemistry, Lensfield Road, Cambridge CB2 1EW, UK
| | - Michael Hurhangee
- Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, UK
| | - Adam Brown
- Optoelectronics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Steffen Illig
- Optoelectronics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Patrick Too
- FlexEnable Ltd, 34 Cambridge Science Park, Cambridge CB4 0FX, UK
| | - Jan Jongman
- FlexEnable Ltd, 34 Cambridge Science Park, Cambridge CB4 0FX, UK
| | - Iain McCulloch
- Solar &Photovoltaics Engineering Research Center, Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
- Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, UK
| | - Jean-Luc Bredas
- Solar &Photovoltaics Engineering Research Center, Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Henning Sirringhaus
- Optoelectronics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
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82
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Groves C. Simulating charge transport in organic semiconductors and devices: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:026502. [PMID: 27991440 DOI: 10.1088/1361-6633/80/2/026502] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Charge transport simulation can be a valuable tool to better understand, optimise and design organic transistors (OTFTs), photovoltaics (OPVs), and light-emitting diodes (OLEDs). This review presents an overview of common charge transport and device models; namely drift-diffusion, master equation, mesoscale kinetic Monte Carlo and quantum chemical Monte Carlo, and a discussion of the relative merits of each. This is followed by a review of the application of these models as applied to charge transport in organic semiconductors and devices, highlighting in particular the insights made possible by modelling. The review concludes with an outlook for charge transport modelling in organic electronics.
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Affiliation(s)
- C Groves
- Durham University, School of Engineering and Computing Sciences, South Road, Durham, DH1 3LE, UK
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83
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Rörich I, Mikhnenko OV, Gehrig D, Blom PWM, Crăciun NI. Influence of Energetic Disorder on Exciton Lifetime and Photoluminescence Efficiency in Conjugated Polymers. J Phys Chem B 2017; 121:1405-1412. [PMID: 28099016 DOI: 10.1021/acs.jpcb.6b11813] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Using time-resolved photoluminescence (TRPL) spectroscopy the exciton lifetime in a range of conjugated polymers is investigated. For poly(p-phenylenevinylene) (PPV)-based derivatives and a polyspirobifluorene copolymer (PSBF) we find that the exciton lifetime is correlated with the energetic disorder. Better ordered polymers exhibit a single exponential PL decay with exciton lifetimes of a few hundred picoseconds, whereas polymers with a larger degree of disorder show multiexponential PL decays with exciton lifetimes in the nanosecond regime. These observations are consistent with diffusion-limited exciton quenching at nonradiative recombination centers. The measured PL decay time reflects the time that excitons need to diffuse toward these quenching sites. Conjugated polymers with large energetic disorder and thus longer exciton lifetime also exhibit a higher photoluminescence quantum yield due to the slower exciton diffusion toward nonradiative quenching sites.
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Affiliation(s)
- Irina Rörich
- Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany.,Dutch Polymer Institute , P.O. Box 902, 5600 AX Eindhoven, The Netherlands
| | - Oleksandr V Mikhnenko
- Lam Research Corporation , 4300 Cushing Pkwy, Fremont, California 94538, United States
| | - Dominik Gehrig
- Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany
| | - Paul W M Blom
- Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany
| | - N Irina Crăciun
- Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany
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84
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Charge transport in nanoscale vertical organic semiconductor pillar devices. Sci Rep 2017; 7:41171. [PMID: 28117371 PMCID: PMC5259728 DOI: 10.1038/srep41171] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 12/16/2016] [Indexed: 11/08/2022] Open
Abstract
We report charge transport measurements in nanoscale vertical pillar structures incorporating ultrathin layers of the organic semiconductor poly(3-hexylthiophene) (P3HT). P3HT layers with thickness down to 5 nm are gently top-contacted using wedging transfer, yielding highly reproducible, robust nanoscale junctions carrying high current densities (up to 106 A/m2). Current-voltage data modeling demonstrates excellent hole injection. This work opens up the pathway towards nanoscale, ultrashort-channel organic transistors for high-frequency and high-current-density operation.
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85
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Xiao X, Cheng XF, Hou X, He JH, Xu QF, Li H, Li NJ, Chen DY, Lu JM. Ion-in-Conjugation: Squaraine as an Ultrasensitive Ammonia Sensor Material. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2017; 13:1602190. [PMID: 27754595 DOI: 10.1002/smll.201602190] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 09/26/2016] [Indexed: 06/06/2023]
Abstract
An organic thin-film gas sensor based on squaraine detects ammonia as low as 40 ppb with impressive reversibility and stability. The resonance-stabilized zwitterionic characteristics offer squaraines high affinity and sensitivity toward electron-rich analytes without irreversible chemical binding, while the embedded squaric ring makes SA-CH3 highly sensitive. The symmetric molecular geometry and good crystallinity also contribute to the high performance.
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Affiliation(s)
- Xin Xiao
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215123, P. R. China
| | - Xue-Feng Cheng
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215123, P. R. China
| | - Xiang Hou
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215123, P. R. China
| | - Jing-Hui He
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215123, P. R. China
| | - Qing-Feng Xu
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215123, P. R. China
| | - Hua Li
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215123, P. R. China
| | - Na-Jun Li
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215123, P. R. China
| | - Dong-Yun Chen
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215123, P. R. China
| | - Jian-Mei Lu
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215123, P. R. China
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86
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Brédas JL, Sargent EH, Scholes GD. Photovoltaic concepts inspired by coherence effects in photosynthetic systems. NATURE MATERIALS 2016; 16:35-44. [PMID: 27994245 DOI: 10.1038/nmat4767] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 09/05/2016] [Indexed: 05/20/2023]
Abstract
The past decade has seen rapid advances in our understanding of how coherent and vibronic phenomena in biological photosynthetic systems aid in the efficient transport of energy from light-harvesting antennas to photosynthetic reaction centres. Such coherence effects suggest strategies to increase transport lengths even in the presence of structural disorder. Here we explore how these principles could be exploited in making improved solar cells. We investigate in depth the case of organic materials, systems in which energy and charge transport stand to be improved by overcoming challenges that arise from the effects of static and dynamic disorder - structural and energetic - and from inherently strong electron-vibration couplings. We discuss how solar-cell device architectures can evolve to use coherence-exploiting materials, and we speculate as to the prospects for a coherent energy conversion system. We conclude with a survey of the impacts of coherence and bioinspiration on diverse solar-energy harvesting solutions, including artificial photosynthetic systems.
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Affiliation(s)
- Jean-Luc Brédas
- Division of Physical Science and Engineering, Solar and Photovoltaics Engineering Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Edward H Sargent
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario M5S 3G4, Canada
| | - Gregory D Scholes
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
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87
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Zhang B, Trinh MT, Fowler B, Ball M, Xu Q, Ng F, Steigerwald ML, Zhu XY, Nuckolls C, Zhong Y. Rigid, Conjugated Macrocycles for High Performance Organic Photodetectors. J Am Chem Soc 2016; 138:16426-16431. [DOI: 10.1021/jacs.6b10276] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Boyuan Zhang
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - M. Tuan Trinh
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Brandon Fowler
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Melissa Ball
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Qizhi Xu
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Fay Ng
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | | | - X.-Y. Zhu
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Colin Nuckolls
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Yu Zhong
- Department of Chemistry, Columbia University, New York, New York 10027, United States
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88
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Tang CG, Ang MCY, Choo KK, Keerthi V, Tan JK, Syafiqah MN, Kugler T, Burroughes JH, Png RQ, Chua LL, Ho PKH. Doped polymer semiconductors with ultrahigh and ultralow work functions for ohmic contacts. Nature 2016; 539:536-540. [DOI: 10.1038/nature20133] [Citation(s) in RCA: 151] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 10/03/2016] [Indexed: 01/26/2023]
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89
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Kaloni TP, Schreckenbach G, Freund MS. Band gap modulation in polythiophene and polypyrrole-based systems. Sci Rep 2016; 6:36554. [PMID: 27827393 PMCID: PMC5101528 DOI: 10.1038/srep36554] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 10/17/2016] [Indexed: 12/01/2022] Open
Abstract
In this paper, the structural and electronic properties of polythiophene and polyprrrole-based systems have been investigated using first-principles calculations both in periodic and oligomer forms. Of particular interest is the band gap modulation through substitutions and bilayer formation. Specifically, S has been substituted by Se and Te in polythiophene, leading to polyseleophene and polytellurophene, respectively, and N has been substituted by P and As in polypyrrole. The values obtained of the binding energy suggest that all the systems studied can be realized experimentally. Stacking (bilayer formation) of pure polythiophene, polypyrrole and their derivatives leads to linear suppression of the band gap or HOMO-LUMO gap as a function of the stacking. Mixed bilayers, including one formed from polythiophene on top of polypyrrole, have also been considered. Overall, a wide range of band gaps can be achieved through substitutions and stacking. Hybrid (B3LYP) calculations also suggest the same trend in the band gap as PBE calculations. Trends in the binding energy are similar for both periodic and molecular calculations. In addition, Γ-point phonon calculations were performed in order to check the stability of selected systems.
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Affiliation(s)
- Thaneshwor P. Kaloni
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
| | - Georg Schreckenbach
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
| | - Michael S. Freund
- Department of Chemistry, Florida Institute of Technology, 150 West University Boulevard, Melbourne, Florida 32901-6975, USA
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90
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Kahle FJ, Bauer I, Strohriegl P, Köhler A. Influence of crosslinking on charge carrier mobility in crosslinkable polyfluorene derivatives. ACTA ACUST UNITED AC 2016. [DOI: 10.1002/polb.24259] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
| | - Irene Bauer
- Experimental Physics II, University of Bayreuth; Bayreuth Germany
| | - Peter Strohriegl
- Macromolecular Chemistry I, University of Bayreuth; Bayreuth Germany
- Bayreuth Institute of Macromolecular Research (BIMF), University of Bayreuth; Bayreuth Germany
| | - Anna Köhler
- Experimental Physics II, University of Bayreuth; Bayreuth Germany
- Bayreuth Institute of Macromolecular Research (BIMF), University of Bayreuth; Bayreuth Germany
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91
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Abstract
Organic (opto)electronic materials have received considerable attention due to their applications in thin-film-transistors, light-emitting diodes, solar cells, sensors, photorefractive devices, and many others. The technological promises include low cost of these materials and the possibility of their room-temperature deposition from solution on large-area and/or flexible substrates. The article reviews the current understanding of the physical mechanisms that determine the (opto)electronic properties of high-performance organic materials. The focus of the review is on photoinduced processes and on electronic properties important for optoelectronic applications relying on charge carrier photogeneration. Additionally, it highlights the capabilities of various experimental techniques for characterization of these materials, summarizes top-of-the-line device performance, and outlines recent trends in the further development of the field. The properties of materials based both on small molecules and on conjugated polymers are considered, and their applications in organic solar cells, photodetectors, and photorefractive devices are discussed.
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Affiliation(s)
- Oksana Ostroverkhova
- Department of Physics, Oregon State University , Corvallis, Oregon 97331, United States
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92
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Basiricò L, Ciavatti A, Cramer T, Cosseddu P, Bonfiglio A, Fraboni B. Direct X-ray photoconversion in flexible organic thin film devices operated below 1 V. Nat Commun 2016; 7:13063. [PMID: 27708274 PMCID: PMC5059709 DOI: 10.1038/ncomms13063] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 09/01/2016] [Indexed: 11/25/2022] Open
Abstract
The application of organic electronic materials for the detection of ionizing radiations is very appealing thanks to their mechanical flexibility, low-cost and simple processing in comparison to their inorganic counterpart. In this work we investigate the direct X-ray photoconversion process in organic thin film photoconductors. The devices are realized by drop casting solution-processed bis-(triisopropylsilylethynyl)pentacene (TIPS-pentacene) onto flexible plastic substrates patterned with metal electrodes; they exhibit a strong sensitivity to X-rays despite the low X-ray photon absorption typical of low-Z organic materials. We propose a model, based on the accumulation of photogenerated charges and photoconductive gain, able to describe the magnitude as well as the dynamics of the X-ray-induced photocurrent. This finding allows us to fabricate and test a flexible 2 × 2 pixelated X-ray detector operating at 0.2 V, with gain and sensitivity up to 4.7 × 104 and 77,000 nC mGy−1 cm−3, respectively. Organic electronics show advantages in easy processing, mechanical flexibility and low costs compared to their inorganic counterparts, yet there are not many proofs for the sake of X-ray detection. Here, Basiricò et al. build a flexible X-ray detector operated at sub-1 V using pentacene-based thin films.
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Affiliation(s)
- Laura Basiricò
- Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, Bologna 40127, Italy
| | - Andrea Ciavatti
- Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, Bologna 40127, Italy
| | - Tobias Cramer
- Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, Bologna 40127, Italy
| | - Piero Cosseddu
- Department of Electrical and Electronic Engineering, University of Cagliari, Piazza D'Armi, Cagliari 09123, Italy
| | - Annalisa Bonfiglio
- Department of Electrical and Electronic Engineering, University of Cagliari, Piazza D'Armi, Cagliari 09123, Italy
| | - Beatrice Fraboni
- Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, Bologna 40127, Italy
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93
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Ball M, Zhong Y, Fowler B, Zhang B, Li P, Etkin G, Paley DW, Decatur J, Dalsania AK, Li H, Xiao S, Ng F, Steigerwald ML, Nuckolls C. Macrocyclization in the Design of Organic n-Type Electronic Materials. J Am Chem Soc 2016; 138:12861-12867. [PMID: 27666433 DOI: 10.1021/jacs.6b05474] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Here, we compare analogous cyclic and acyclic π-conjugated molecules as n-type electronic materials and find that the cyclic molecules have numerous benefits in organic photovoltaics. This is the first report of such a direct comparison. We designed two conjugated cycles for this study. Each comprises four subunits: one combines four electron-accepting, redox-active, diphenyl-perylenediimide subunits, and the other alternates two electron-donating bithiophene units with two diphenyl-perylenediimide units. We compare the macrocycles to acyclic versions of these molecules and find that, relative to the acyclic analogs, the conjugated macrocycles have bathochromically shifted UV-vis absorbances and are more easily reduced. In blended films, macrocycle-based devices show higher electron mobility and good morphology. All of these factors contribute to the more than doubling of the power conversion efficiency observed in organic photovoltaic devices with these macrocycles as the n-type, electron transporting material. This study highlights the importance of geometric design in creating new molecular semiconductors. The ease with which we can design and tune the electronic properties of these cyclic structures charts a clear path to creating a new family of cyclic, conjugated molecules as electron transporting materials in optoelectronic and electronic devices.
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Affiliation(s)
- Melissa Ball
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Yu Zhong
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Brandon Fowler
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Boyuan Zhang
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Panpan Li
- Department of Chemistry, Columbia University , New York, New York 10027, United States.,The Education Ministry Key Lab of Resource Chemistry, Shanghai Key Laboratory of Rare Earth Functional Materials, Optoelectronic Nano Materials and Devices Institute, Department of Chemistry, Shanghai Normal University , Shanghai, China 200234
| | - Grisha Etkin
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Daniel W Paley
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - John Decatur
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Ankur K Dalsania
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Hexing Li
- The Education Ministry Key Lab of Resource Chemistry, Shanghai Key Laboratory of Rare Earth Functional Materials, Optoelectronic Nano Materials and Devices Institute, Department of Chemistry, Shanghai Normal University , Shanghai, China 200234
| | - Shengxiong Xiao
- The Education Ministry Key Lab of Resource Chemistry, Shanghai Key Laboratory of Rare Earth Functional Materials, Optoelectronic Nano Materials and Devices Institute, Department of Chemistry, Shanghai Normal University , Shanghai, China 200234
| | - Fay Ng
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Michael L Steigerwald
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Colin Nuckolls
- Department of Chemistry, Columbia University , New York, New York 10027, United States.,The Education Ministry Key Lab of Resource Chemistry, Shanghai Key Laboratory of Rare Earth Functional Materials, Optoelectronic Nano Materials and Devices Institute, Department of Chemistry, Shanghai Normal University , Shanghai, China 200234
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94
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Fei Z, Han Y, Martin J, Scholes FH, Al-Hashimi M, AlQaradawi SY, Stingelin N, Anthopoulos TD, Heeney M. Conjugated Copolymers of Vinylene Flanked Naphthalene Diimide. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b01423] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
| | | | | | - Fiona H. Scholes
- CSIRO Manufacturing, Private Bag 10, Clayton South, Victoria 3169, Australia
| | - Mohammed Al-Hashimi
- Department of Chemistry, Texas A&M University at Qatar, P.O. Box 23874, Doha, Qatar
| | - Siham Y. AlQaradawi
- Department of Chemistry & Earth Sciences, Qatar University, P.O. Box 2713, Doha, Qatar
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95
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Yan H, Manion JG, Yuan M, García de Arquer FP, McKeown GR, Beaupré S, Leclerc M, Sargent EH, Seferos DS. Increasing Polymer Solar Cell Fill Factor by Trap-Filling with F4-TCNQ at Parts Per Thousand Concentration. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:6491-6496. [PMID: 27171655 DOI: 10.1002/adma.201601553] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Revised: 04/05/2016] [Indexed: 06/05/2023]
Abstract
Intrinsic traps in organic semiconductors can be eliminated by trap-filling with F4-TCNQ. Photovoltaic tests show that devices with F4-TCNQ at parts per thousand concentration outperform control devices due to an improved fill factor. Further studies confirm the trap-filling pathway and demonstrate the general nature of this finding.
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Affiliation(s)
- Han Yan
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada
| | - Joseph G Manion
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada
| | - Mingjian Yuan
- The Edward S. Rogers Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - F Pelayo García de Arquer
- The Edward S. Rogers Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - George R McKeown
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada
| | - Serge Beaupré
- Department of Chemistry, Université Laval, Avenue de la Médecine, Québec City, Québec, G1V 0A6, Canada
| | - Mario Leclerc
- Department of Chemistry, Université Laval, Avenue de la Médecine, Québec City, Québec, G1V 0A6, Canada
| | - Edward H Sargent
- The Edward S. Rogers Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Dwight S Seferos
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada
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96
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Gorbunov AV, Haedler AT, Putzeys T, Zha RH, Schmidt HW, Kivala M, Urbanavičiu̅tė I, Wübbenhorst M, Meijer EW, Kemerink M. Switchable Charge Injection Barrier in an Organic Supramolecular Semiconductor. ACS APPLIED MATERIALS & INTERFACES 2016; 8:15535-15542. [PMID: 27246280 DOI: 10.1021/acsami.6b02988] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We disclose a supramolecular material that combines semiconducting and dipolar functionalities. The material consists of a discotic semiconducting carbonyl-bridged triarylamine core, which is surrounded by three dipolar amide groups. In thin films, the material self-organizes in a hexagonal columnar fashion through π-stacking of the molecular core and hydrogen bonding between the amide groups. Alignment by an electrical field in a simple metal/semiconductor/metal geometry induces a polar order in the interface layers near the metal contacts that can be reversibly switched, while the bulk material remains nonpolarized. On suitably chosen electrodes, the presence of an interfacial polarization field leads to a modulation of the barrier for charge injection into the semiconductor. Consequently, a reversible switching is possible between a high-resistance, injection-limited off-state and a low-resistance, space-charge-limited on-state. The resulting memory diode shows switchable rectification with on/off ratios of up to two orders of magnitude. This demonstrated multifunctionality of a single material is a promising concept toward possible application in low-cost, large-area, nonvolatile organic memories.
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Affiliation(s)
| | | | - Tristan Putzeys
- Department of Physics and Astronomy, Laboratory for Soft Matter and Biophysics, KU Leuven , Celestijnenlaan 200D, B-3001 Heverlee, Belgium
| | | | - Hans-Werner Schmidt
- Makromolekuläre Chemie I, Bayreuther Institut für Makromolekülforschung (BIMF), and Bayreuther Zentrum für Kolloide und Grenzflächen (BZKG), Universität Bayreuth , 95440 Bayreuth, Germany
| | - Milan Kivala
- Lehrstuhl für Organische Chemie I, Department Chemie und Pharmazie, Friedrich-Alexander-Universität Erlangen-Nürnberg , 91054 Erlangen, Germany
| | - Indre Urbanavičiu̅tė
- Complex Materials and Devices, Department of Physics, Chemistry and Biology (IFM), Linköping University , 58183 Linköping, Sweden
| | - Michael Wübbenhorst
- Department of Physics and Astronomy, Laboratory for Soft Matter and Biophysics, KU Leuven , Celestijnenlaan 200D, B-3001 Heverlee, Belgium
| | | | - Martijn Kemerink
- Complex Materials and Devices, Department of Physics, Chemistry and Biology (IFM), Linköping University , 58183 Linköping, Sweden
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97
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Abbaszadeh D, Kunz A, Wetzelaer GAH, Michels JJ, Crăciun NI, Koynov K, Lieberwirth I, Blom PWM. Elimination of charge carrier trapping in diluted semiconductors. NATURE MATERIALS 2016; 15:628-633. [PMID: 27111412 DOI: 10.1038/nmat4626] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 03/15/2016] [Indexed: 06/05/2023]
Abstract
In 1962, Mark and Helfrich demonstrated that the current in a semiconductor containing traps is reduced by N/Nt(r), with N the amount of transport sites, Nt the amount of traps and r a number that depends on the trap energy distribution. For r > 1, the possibility opens that trapping effects can be nearly eliminated when N and Nt are simultaneously reduced. Solution-processed conjugated polymers are an excellent model system to test this hypothesis, because they can be easily diluted by blending them with a high-bandgap semiconductor. We demonstrate that in conjugated polymer blends with 10% active semiconductor and 90% high-bandgap host, the typical strong electron trapping can be effectively eliminated. As a result we were able to fabricate polymer light-emitting diodes with balanced electron and hole transport and reduced non-radiative trap-assisted recombination, leading to a doubling of their efficiency at nearly ten times lower material costs.
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Affiliation(s)
- D Abbaszadeh
- Molecular Electronics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
- Dutch Polymer Institute, PO Box 902, 5600 AX, Eindhoven, The Netherlands
| | - A Kunz
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - G A H Wetzelaer
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - J J Michels
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - N I Crăciun
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - K Koynov
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - I Lieberwirth
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - P W M Blom
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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98
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Rivnay J. Organic electronics: Efficiency through dilution. NATURE MATERIALS 2016; 15:594-595. [PMID: 27111411 DOI: 10.1038/nmat4632] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Affiliation(s)
- Jonathan Rivnay
- Palo Alto Research Center (PARC), Palo Alto, California 94304, USA
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99
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Kim K, Jeong HJ, Kim FS. Use of a cross-linkable or monolayer-forming polymeric buffer layer on PCBM-based n-channel organic field-effect transistors. Polym Bull (Berl) 2016. [DOI: 10.1007/s00289-016-1677-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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100
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Gozzi G, Cagnani LD, Faria RM, Santos LF. Electrical properties of electrochemically doped organic semiconductors using light-emitting electrochemical cells. J Solid State Electrochem 2016. [DOI: 10.1007/s10008-016-3219-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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