Publications
641 results found
Schroeder BC, Ashraf RS, Thomas S, et al., 2012, Synthesis of novel thieno[3,2-b]thienobis(silolothiophene) based low bandgap polymers for organic photovoltaics., Chem Commun (Camb), Vol: 48, Pages: 7699-7701, ISSN: 1364-548X
Thieno[3,2-b]thienobis(silolothiophene), a new electron rich hexacyclic monomer has been synthesized and incorporated into three novel donor-acceptor low-bandgap polymers. By carefully choosing the acceptor co-monomer, the energy levels of the polymers could be modulated and high power conversion efficiencies of 5.52% were reached in OPV devices.
Schroeder BC, Bronstein HA, Ashraf RS, et al., 2012, Electronic structure tuning of new fused thieno[3,2-b]thieno bisthiophene based polymers via alkyl chain and Group IV heteroatom modulation, SPIE Optics & Photonics
Keivanidis PE, Kamm V, Zhang W, et al., 2012, Correlating Emissive Non-Geminate Charge Recombination with Photocurrent Generation Efficiency in Polymer/Perylene Diimide Organic Photovoltaic Blend Films, ADVANCED FUNCTIONAL MATERIALS, Vol: 22, Pages: 2318-2326, ISSN: 1616-301X
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- Citations: 28
Smith J, Zhang W, Sougrat R, et al., 2012, Solution-Processed Small Molecule-Polymer Blend Organic Thin-Film Transistors with Hole Mobility Greater than 5 cm2/Vs, ADVANCED MATERIALS, Vol: 24, Pages: 2441-2446, ISSN: 0935-9648
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- Citations: 208
Mcculloch I, Ashraf RS, Biniek L, et al., 2012, Design of Semiconducting Indacenodithiophene Polymers for High Performance Transistors and Solar Cells, ACCOUNTS OF CHEMICAL RESEARCH, Vol: 45, Pages: 714-722, ISSN: 0001-4842
The prospect of using low cost, high throughput material deposition processes to fabricate organic circuitry and solar cells continues to drive research towards improving the performance of the semiconducting materials utilized in these devices. Conjugated aromatic polymers have emerged as a leading candidate semiconductor material class, due to their combination of their amenability to processing and reasonable electrical and optical performance. Challenges remain, however, to further improve the charge carrier mobility of the polymers for transistor applications and the power conversion efficiency for solar cells. This optimization requires a clear understanding of the relationship between molecular structure and both electronic properties and thin film morphology.In this Account, we describe an optimization process for a series of semiconducting polymers based on an electron rich indacenodithiophene aromatic backbone skeleton. We demonstrate the effect of bridging atoms, alkyl chain functionalization, and co-repeating units on the morphology, molecular orbital energy levels, charge carrier mobility, and solar cell efficiencies. This conjugated unit is extremely versatile with a coplanar aromatic ring structure, and the electron density can be manipulated by the choice of bridging group between the rings. The functionality of the bridging group also plays an important role in the polymer solubility, and out of plane aliphatic chains present in both the carbon and silicon bridge promote solubility. This particular polymer conformation, however, typically suppresses long range organization and crystallinity, which had been shown to strongly influence charge transport. In many cases, polymers exhibited both high solubility and excellent charge transport properties, even where there was no observable evidence of polymer crystallinity. The optical bandgap of the polymers can be tuned by the combination of the donating power of the bridging unit and the electron withdra
Schroeder BC, Huang Z, Ashraf RS, et al., 2012, Silaindacenodithiophene-Based Low Band Gap Polymers - The Effect of Fluorine Substitution on Device Performances and Film Morphologies, ADVANCED FUNCTIONAL MATERIALS, Vol: 22, Pages: 1663-1670, ISSN: 1616-301X
Silaindacenodithiophene is copolymerized with benzo[c][1,2,5]thiadiazole (BT) and 4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole (DTBT), respectively their fluorinated counter parts 5,6-difluorobenzo[c][1,2,5]thiadiazole (2FBT) and 5,6-difluoro-4,7-di(thiophen-2-yl) benzo[c][1,2,5]thiadiazole (2FDTBT). The influence of the thienyl spacers and fluorine atoms on molecular packing and active layer morphology is investigated with regard to device performances. bulk heterojunction (BHJ) solar cells based on silaindacenodithiophene donor-acceptor polymers achieved PCE's of 4.5% and hole mobilities of as high as 0.28 cm2/(V s) are achieved in an organic field-effect transistor (OFET).
McCulloch I, Heeney M, Nielsen C, et al., 2012, Triaryl- and triheteroaryl- benzene monomers and polymers for electrooptical applications, WO 2012131084
The invention relates to mono-, oligo- and polymeric compds. comprising substituted triaryl- and triheteroaryl benzene groups and their copolymers. The invention further relates to the methods of their synthesis, to org. semiconducting materials and blends, formulations and layers comprising them, and to electronic devices, like org. field effect transistors (OFETs) and org. photovoltaics (OPVs), comprising them.
Chen Z, Lee MJ, Ashraf RS, et al., 2012, High-Performance Ambipolar Diketopyrrolopyrrole-Thieno[3,2-b]thiophene Copolymer Field-Effect Transistors with Balanced Hole and Electron Mobilities, ADVANCED MATERIALS, Vol: 24, Pages: 647-+, ISSN: 0935-9648
Ambipolar OFETs with balanced hole and electron field-effect mobilities both exceeding 1 cm(2) V(-1) s(-1) are achieved based on a single-solution-processed conjugated polymer, DPPT-TT, upon careful optimization of the device architecture, charge injection, and polymer processing. Such high-performance OFETs are promising for applications in ambipolar devices and integrated circuits, as well as model systems for fundamental studies.
Kirkpatrick J, Nielsen CB, Zhang W, et al., 2012, A Systematic Approach to the Design Optimization of Light-Absorbing Indenofluorene Polymers for Organic Photovoltaics, ADVANCED ENERGY MATERIALS, Vol: 2, Pages: 260-265, ISSN: 1614-6832
James DI, Smith J, Heeney M, et al., 2012, Organic Semiconductor Materials for Transistors, Pages: 1-26
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- Citations: 10
Faist MA, Kirchartz T, Gong W, et al., 2012, Competition between the Charge Transfer State and the Singlet States of Donor or Acceptor Limiting the Efficiency in Polymer:Fullerene Solar Cells, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 134, Pages: 685-692, ISSN: 0002-7863
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- Citations: 225
Dimitrov SD, Nielsen CB, Shoaee S, et al., 2012, Efficient Charge Photogeneration by the Dissociation of PC70BM Excitons in Polymer/Fullerene Solar Cells, JOURNAL OF PHYSICAL CHEMISTRY LETTERS, Vol: 3, Pages: 140-144, ISSN: 1948-7185
Biniek L, Schroeder BC, Nielsen CB, et al., 2012, Recent advances in high mobility donor-acceptor semiconducting polymers, JOURNAL OF MATERIALS CHEMISTRY, Vol: 22, Pages: 14803-14813, ISSN: 0959-9428
Nielsen CB, Ashraf RS, Schroeder BC, et al., 2012, Random benzotrithiophene-based donor-acceptor copolymers for efficient organic photovoltaic devices, CHEMICAL COMMUNICATIONS, Vol: 48, Pages: 5832-5834, ISSN: 1359-7345
A series of benzotrithiophene-containing random terpolymers for polymer solar cells is reported. Through variations of the two other components in the terpolymers, the absorption profile and the frontier energy levels are optimized and maximum power conversion efficiencies are nearly doubled (5.14%) relative to the parent alternating copolymer.
Gupta D, Brenner TJK, Albert-Seifried S, et al., 2012, Photoconductivity anisotropy study in uniaxially aligned polymer based planar photodiodes, ORGANIC ELECTRONICS, Vol: 13, Pages: 36-42, ISSN: 1566-1199
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- Citations: 12
Soon YW, Shoaee S, McCulloch I, et al., 2012, Correlating crystallinity and photophysics for donor polymers of interest for organic photovoltaic devices, Conference on Organic Photovoltaics XIII Part of the Symposium on Organic Photonics Plus Electronics at the SPIE Optics Plus Photonics International Meeting, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
Shoaee S, Clarke TM, Eng MP, et al., 2012, Charge photogeneration in donor/acceptor organic solar cells, JOURNAL OF PHOTONICS FOR ENERGY, Vol: 2, ISSN: 1947-7988
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- Citations: 11
Shahid M, Ashraf RS, Huang Z, et al., 2012, Photovoltaic and field effect transistor performance of selenophene and thiophene diketopyrrolopyrrole co-polymers with dithienothiophene, JOURNAL OF MATERIALS CHEMISTRY, Vol: 22, Pages: 12817-12823, ISSN: 0959-9428
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- Citations: 93
Ashraf RS, Kronemeijer AJ, James DI, et al., 2012, A new thiophene substituted isoindigo based copolymer for high performance ambipolar transistors, CHEMICAL COMMUNICATIONS, Vol: 48, Pages: 3939-3941, ISSN: 1359-7345
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- Citations: 226
Fei Z, Ashraf RS, Huang Z, et al., 2012, Germaindacenodithiophene based low band gap polymers for organic solar cells, CHEMICAL COMMUNICATIONS, Vol: 48, Pages: 2955-2957, ISSN: 1359-7345
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- Citations: 49
James DT, Kjellander BKC, Smaal WTT, et al., 2011, Thin-Film Morphology of Inkjet-Printed Single-Droplet Organic Transistors Using Polarized Raman Spectroscopy: Effect of Blending TIPS-Pentacene with Insulating Polymer, ACS NANO, Vol: 5, Pages: 9824-9835, ISSN: 1936-0851
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- Citations: 112
Bronstein H, Ashraf RS, Kim Y, et al., 2011, Synthesis of a Novel Fused Thiophene-thieno[3,2-b]thiophene-thiophene Donor Monomer and Co-polymer for Use in OPV and OFETs, MACROMOLECULAR RAPID COMMUNICATIONS, Vol: 32, Pages: 1664-1668, ISSN: 1022-1336
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- Citations: 39
Zhang XR, Richter LJ, DeLongchamp DM, et al., 2011, Molecular Packing of High-Mobility Diketo Pyrrolo-Pyrrole Polymer Semiconductors with Branched Alkyl Side Chains, J AM CHEM SOC, Vol: 133, Pages: 15073-15084, ISSN: 0002-7863
Chen Z, Bird M, Lemaur V, et al., 2011, Origin of the different transport properties of electron and hole polarons in an ambipolar polyselenophene-based conjugated polymer, PHYSICAL REVIEW B, Vol: 84, ISSN: 2469-9950
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- Citations: 40
Bronstein H, Leem DS, Hamilton R, et al., 2011, Indacenodithiophene-<i>co</i>-benzothiadiazole Copolymers for High Performance Solar Cells or Transistors via Alkyl Chain Optimization, MACROMOLECULES, Vol: 44, Pages: 6649-6652, ISSN: 0024-9297
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- Citations: 158
Donaghey JE, Ashraf S, Zhang W, et al., 2011, Pyrroloindacenodithiophene containing polymers: Synthesis and characterization, 242nd National Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Miller NC, Gysel R, Miller CE, et al., 2011, The Phase Behavior of a Polymer-Fullerene Bulk Heterojunction System that Contains Bimolecular Crystals, JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS, Vol: 49, Pages: 499-503, ISSN: 0887-6266
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- Citations: 68
Bronstein H, Chen Z, Ashraf RS, et al., 2011, Thieno[3,2-<i>b</i>]thiophene-Diketopyrrolopyrrole-Containing Polymers for High-Performance Organic Field-Effect Transistors and Organic Photovoltaic Devices, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 133, Pages: 3272-3275, ISSN: 0002-7863
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- Citations: 817
George WN, Giles M, McCulloch I, et al., 2011, Efficient Quenching of a Guanidinium-Containing Fluorescence Sensor, CHEMPHYSCHEM, Vol: 12, Pages: 765-768, ISSN: 1439-4235
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- Citations: 6
Lee MJ, Gupta D, Zhao N, et al., 2011, Anisotropy of Charge Transport in a Uniaxially Aligned and Chain-Extended, High-Mobility, Conjugated Polymer Semiconductor, ADVANCED FUNCTIONAL MATERIALS, Vol: 21, Pages: 932-940, ISSN: 1616-301X
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- Citations: 159
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