- A crystalline D-π-A organic small molecule with naphtho[1,2-b:5,6- b′]dithiophene-core for solution processed organic solar cells
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In this work, we have designed and synthesized a new naphtho[1,2-b:5,6- b′]dithiophene-containing enlarged π-conjugated donor-acceptor (D-A) small molecule, NDT(TTz)2, for use in solution-processed organic photovoltaics. NDT(TTz)2, which contains a thiophene-bridged naphtho[1,2-b:5,6-b′]dithiophene as the central fused core and triphenylamine-flanked thiophene thiazolothiazole as a spacer, was synthesized via sequential Suzuki and Stille coupling reactions. The thermal, physiochemical, and electrochemical properties of NDT(TTz)2 have been evaluated by differential scanning calorimetry, thermogravimetry, UV-Vis spectroscopy, photoluminescence spectroscopy, X-ray diffraction, and cyclic voltammetry. As desired for photovoltaic applications, NDT(TTz)2 possesses good solubility, thermal stability, and a well-ordered, π-π stacked, crystallinity. The optical band gap and HOMO level of NDT(TTz) 2 were determined to be 2.0 eV and -5.23 eV, respectively. In addition to organic thin film transistor studies, application of NDT(TTz) 2 to preliminary photovoltaic devices has also been investigated by fabricating solution-processed bulk heterojunction solar cells together with PC71BM in a typical layered device structure, ITO/PEDOT:PSS/NDT(TTz) 2:PC71BM/LiF/Al. Without extensive optimization of the device, NDT(TTz)2 in these devices shows a maximum power conversion efficiency of 1.44% under AM 1.5 illumination at a 100 mW/cm2 intensity.
- Dutta, Pranabesh,Park, Hanok,Lee, Woo-Hyoung,Kang, In-Nam,Lee, Soo-Hyoung
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- Influence of molecular structure on the performance of low: V oc loss polymer solar cells
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Two regioregular narrow bandgap conjugated polymers (PM1 and PM2) containing the repeat unit BDT-PT-CPDT-PT (BDT = benzodithiophene, PT = pyridyl[2,1,3]thiadiazole, CPDT = cyclopentadithiophene) and different solubilizing alkyl side chains were prepared with the goal of understanding how chemical structure impacts the performance of low Voc loss bulk heterojunction (BHJ) solar cells containing PC61BM as the acceptor semiconductor. Both polymers show nearly identical orbital energy levels, a face-on orientation relative to the surface normal, and can be processed to yield continuous fiber-like networks in the active layer. Due to the choice of repeat units within the backbone structure, PM1 and PM2 exhibit shorter π-π stacking distances, relative to the previously reported low Voc loss regioregular polymer PIPCP. Finally, PM1 achieves an average PCE of 6.2 ± 0.2% and PM2 achieves an average PCE of 7.2 ± 0.1%. Devices exhibit low Voc loss and high short circuit current Jsc, but, most significantly, display improved fill factors compared to previously reported PIPCP. A discussion is provided that seeks to identify structural features in conjugated polymers that lead to devices with low Voc loss and high external quantum efficiencies.
- Wang, Ming,Wang, Hengbin,Ford, Michael,Yuan, Jianyu,Mai, Cheng-Kang,Fronk, Stephanie,Bazan, Guillermo C.
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p. 15232 - 15239
(2016/10/13)
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- Novel s-tetrazine-based dyes with enhanced two-photon absorption cross-section
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This paper reports the synthesis and the linear and non-linear absorption properties of a series of new tetrazine-based D-π-A-π-D and D-π-A type dyes. In these derivatives, a central tetrazine core was connected with one or two terminal triphenylamine moi
- Quinton, Cassandre,Chi, San-Hui,Dumas-Verdes, Ccile,Audebert, Pierre,Clavier, Gilles,Perry, Joseph W.,Alain-Rizzo, Valrie
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p. 8351 - 8357
(2015/08/18)
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- Triphenylamine/tetrazine based π-conjugated systems as molecular donors for organic solar cells
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Conjugated systems built by connecting one electron-donor triphenylamine to an electron-withdrawing tetrazine have been prepared using various linkers. We describe here the synthesis, the electrochemical properties and some photophysical properties of the
- Quinton, Cassandre,Alain-Rizzo, Valérie,Dumas-Verdes, Cécile,Clavier, Gilles,Vignau, Laurence,Audebert, Pierre
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p. 9700 - 9713
(2015/12/01)
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- A bolaamphiphilic sexithiophene with liquid crystalline triangular honeycomb phase
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A new bolaamphiphile comprising a 5,5′′′′′- diphenyl-sexithiophene core with glycerol groups at each end and four lateral decyl chains was synthesized, which self-assembles into a liquid crystalline phase representing a nanoscale honeycomb composed of qua
- Bu, Wei,Gao, Hongfei,Tan, Xiaoping,Dong, Xing,Cheng, Xiaohong,Prehm, Marko,Tschierske, Carsten
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p. 1756 - 1758
(2013/03/14)
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- Transition between triangular and square tiling patterns in liquid-crystalline honeycombs formed by tetrathiophene-based bolaamphiphiles
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A series of 5,5′′′-diphenyl tetrathiophenes with polar glycerol groups at each end and two lateral flexible chains self-assemble into a series of liquid-crystalline honeycombs, formed by the π-conjugated rods which enclose polygonal prismatic cells filled by the lateral chains. With increasing chain length a discontinuous transition from triangular to square honeycombs takes place. At this transition a periodic honeycomb composed of a mixture of square and triangular cells in a ratio 1:2 was formed at low temperature, whereas at higher temperature a hexagonal columnar phase composed of triangular and randomly distributed rhombic cells, a new kind of cybotactic nematic phase, and also a cybotactic isotropic phase, both composed of square honeycomb fragments, represent the intermediate states. This provides an example of a dynamic self-assembled system where, depending on the molecular mobility, the transition between two periodic structures with different symmetry either leads to an increase of complexity, or to a chaotic regime with reduced order.
- Cheng, Xiaohong,Gao, Hongfei,Tan, Xiaoping,Yang, Xueyan,Prehm, Marko,Ebert, Helgard,Tschierske, Carsten
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p. 3317 - 3331
(2013/07/26)
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- Synthesis and characterization of triphenylamine flanked thiazole-based small molecules for high performance solution processed organic solar cells
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Two new small molecules, 5,5-bis(2-triphenylamino-3-decylthiophen-2-yl)-2, 2-bithiazole (M1) and 2,5-bis(2-triphenylamino-3-decylthiophen-2-yl)thiazolo[5, 4-d]thiazole (M2) based on an electron-donor triphenylamine unit and electron-acceptor thiophene-thiazolothiazole or thiophene-bithiazole units were synthesized by a palladium(0)-catalyzed Suzuki coupling reaction and examined as donor materials for application in organic solar cells. The small molecules had an absorption band in the range of 300-560 nm, with an optical band gap of 2.22 and 2.25 for M1 and M2, respectively. As determined by cyclic voltammetry, the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of M1 were -5.27 eV and -3.05 eV, respectively, which were 0.05 eV and 0.02 eV greater than that of M2. Photovoltaic properties of the small molecules were investigated by constructing bulk-heterojunction organic solar cell (OSC) devices using M1 and M2 as donors and fullerene derivatives, 6,6-phenyl-C61-butyric acid methyl ester (PC61BM) and 6,6-phenyl-C71-butyric acid methyl ester (PC71BM) as acceptors with the device architecture ITO/PEDOT:PSS/M1 or M2:PCBM/LiF/Al. The effect of the small molecule/fullerene weight ratio, active layer thickness, and processing solvent were carefully investigated to improve the performance of the OSCs. Under AM 1.5 G 100 mW/cm2 illumination, the optimized OSC device with M1 and PC71BM at a weight ratio of 1:3 delivered a power conversion efficiency (PCE) of 1.30%, with a short circuit current of 4.63 mA/cm 2, an open circuit voltage of 0.97 V, and a fill factor of 0.29. In contrast, M2 produced a better performance under identical device conditions. A PCE as high as 2.39% was recorded, with a short circuit current of 6.49 mA/cm2, an open circuit voltage of 0.94 V, and a fill factor of 0.39.
- Dutta, Pranabesh,Yang, Wooseung,Eom, Seung Hun,Lee, Soo-Hyoung
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p. 273 - 282
(2012/06/01)
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- Dithiophene based X-shaped bolaamphiphiles: Liquid crystals with single wall honeycombs and geometric frustration
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A series of 5,5′-diphenyl-2,2′-dithiophene based X-shaped polyphiles with two long lateral alkyl chains and terminal glycerol groups was synthesized and the liquid crystalline phases formed by these compounds were investigated by polarizing microscopy, DSC and XRD. These compounds form square (p4mm and p4gm) and hexagonal (p6mm) columnar LC phases. In these mesophases the molecules organize into polygonal honeycombs where the π-conjugated cores form the walls, fused at the edges by the hydrogen bonding networks between the glycerol units and filled by the lateral alkyl chains. By elongation of these chains, a series of polygonal honeycomb phases with a "single wall" structure, ranging from triangular via square and pentagonal to hexagonal was observed. Most triangular honeycombs appear to be defective and can be considered as mixtures of triangular cylinders with orientationally randomized rhombic cylinders. The transition from this improper triangular honeycomb to the square honeycomb takes place via a disordered isotropic phase. Addition of water to this isotropic phase gives rise to a true triangular honeycomb LC phase. Replacing one of the long lateral chains by a small methyl group leads to honeycombs formed by double walls instead of single walls. UV investigations indicate π-stacking of the aromatic cores organized in the honeycomb walls, which is of interest for the potential application of these materials in self assembled arrays of organic electronic material. This journal is
- Gao, Hongfei,Ye, Yafei,Kong, Leiyang,Cheng, Xiaohong,Prehm, Marko,Ebert, Helgard,Tschierske, Carsten
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p. 10921 - 10931,11
(2020/09/15)
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- Using bis(pinacolato)diboron to improve the quality of regioregular conjugated co-polymers
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We demonstrate the use of bis(pinacolato)diboron to directly polymerize symmetric, bisbromo, thiophene-based monomers via a Suzuki homo-polymerization to form co-polymers in less steps than the corresponding co-polymerization. We compare this method to the commonly used Stille co-polymerization by preparing four thiophene-based co-polymers using both methods. We use MALDI-TOF mass spectrometry to show that this new method produces high-quality, uniform polymers with narrow distributions of end-groups. By varying the electronegativity of the monomers, we demonstrate rudimentary control over these end-groups, forming either bis-H-, mono-H-mono-Br-, or bis-Br-terminated polymers in order of increasing electronegativity.
- Brouwer, Frank,Alma, Jan,Valkenier, Hennie,Voortman, Thomas P.,Hillebrand, Jorrit,Chiechi, Ryan C.,Hummelen, Jan C.
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p. 1582 - 1592
(2011/10/02)
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- Bithiophene-imide-based polymeric semiconductors for field-effect transistors: Synthesis, structure-property correlations, charge carrier polarity, and device stability
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Developing new high-mobility polymeric semiconductors with good processability and excellent device environmental stability is essential for organic electronics. We report the synthesis, characterization, manipulation of charge carrier polarity, and device air stability of a new series of bithiophene-imide (BTI)-based polymers for organic field-effect transistors (OFETs). By increasing the conjugation length of the donor comonomer unit from monothiophene (P1) to bithiophene (P2) to tetrathiophene (P3), the electron transport capacity decreases while the hole transport capacity increases. Compared to the BTI homopolymer P(BTimR) having an electron mobility of 10 -2 cm2 V-1 s-1, copolymer P1 is ambipolar with balanced hole and electron mobilities of ～10-4 cm2 V-1 s-1, while P2 and P3 exhibit hole mobilities of ～10-3 and ～10-2 cm2 V-1 s-1, respectively. The influence of P(BTimR) homopolymer Mn on film morphology and device performance was also investigated. The high Mn batch P(BTimR)-H affords more crystalline film microstructures; hence, 3- increased electron mobility (0.038 cm 2 V-1 s-1) over the low Mn one P(BTimR)-L (0.011 cm2 V-1 s-1). In a top-gate/bottom-contact OFET architecture, P(BTimR)-H achieves a high electron mobility of 0.14 cm2 V-1 s-1, only slightly lower than that of state-of-the-art n-type polymer semiconductors. However, the high-lying P(BTimR)-H LUMO results in minimal electron transport on exposure to ambient. Copolymer P3 exhibits a hole mobility approaching 0.1 cm2 V-1 s-1 in top-gate OFETs, comparable to or slightly lower than current state-of-the-art p-type polymer semiconductors (0.1-0.6 cm 2 V-1 s-1). Although BTI building block incorporation does not enable air-stable n-type OFET performance for P(BTimR) or P1, it significantly increases the OFET air stability for p-type P2 and P3. Bottom-gate/top-contact and top-gate/bottom-contact P2 and P3 OFETs exhibit excellent stability in the ambient. Thus, P2 and P3 OFET hole mobilities are almost unchanged after 200 days under ambient, which is attributed to their low-lying HOMOs (>0.2 eV lower than that of P3HT), induced by the strong BTI electron-withdrawing capacity. Complementary inverters were fabricated by inkjet patterning of P(BTimR)-H (n-type) and P3b (p-type).
- Guo, Xugang,Ortiz, Rocio Ponce,Zheng, Yan,Hu, Yan,Noh, Yong-Young,Baeg, Kang-Jun,Facchetti, Antonio,Marks, Tobin J.
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p. 1405 - 1418
(2011/04/16)
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- Liquid-crystalline triangle honeycomb formed by a dithiophene-based X-shaped bolaamphiphile
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Soft supramolecular triangles: The molecule shown displays a new liquid-crystalline phase formed by a periodic array of triangular cylinders. The cylinders are fused to form a honeycomb by hydrogen-bonding networks running along the vertices, and the cells are filled by molten alkyl chains. The thickness of the walls separating the compartments is equal to the width of the π-conjugated rods.
- Cheng, Xiaohong,Dong, Xing,Wei, Guanghui,Prehm, Marko,Tschierske, Carsten
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supporting information; scheme or table
p. 8014 - 8017
(2010/02/27)
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