385 results found
Schroeder BC, Nielsen CB, Kim YJ, et al., 2011, Benzotrithiophene Co-polymers with High Charge Carrier Mobilities in Field-Effect Transistors, Chemistry of Materials, Vol: 23, Pages: 4025-4031, ISSN: 0897-4756
Dalgleish S, Labram JG, Li Z, et al., 2011, Indole-substituted nickel dithiolene complexes in electronic and optoelectronic devices, Journal of Materials Chemistry, Vol: 21, Pages: 15422-15430, ISSN: 0959-9428
The synthesis and full characterisation of a novel indole-substituted nickel dithiolene [Ni(mi-5edt)2] (3) is reported, and compared to its alkyl-substituted analogue [Ni(mi-5hdt)2] (4) that has been previously communicated [Dalgleish et al., Chem. Commun., 2009, 5826] [mi-5edt = 1-(N-methylindol-5-yl)-ethene-1,2-dithiolate; mi-5hdt = 1-(N-methylindol-5-yl)-hex-1-ene-1,2-dithiolate)]. Both complexes are shown to undergo oxidative electropolymerisation, yielding polymer films that retain the redox and optical properties of the monomer. The more soluble analogue 4 is shown to form high quality thin films by spin coating, which have been utilised to fabricate field-effect transistors (FETs) and bulk heterojunction photovoltaic devices (BHJ-PVs). From FET studies, the material shows ambipolar charge transport behaviour, with a maximum carrier mobility of [similar]10-6 cm2 V-1 s-1 for electrons. By using 4 simultaneously as the electron acceptor as well as a NIR sensitiser in BHJ-PVs, the complex is shown to contribute to the photocurrent, extending light harvesting into the NIR region.
Donaghey JE, Ashraf RS, Kim Y, et al., 2011, Pyrroloindacenodithiophene containing polymers for organic field effect transistors and organic photovoltaics, Journal of Materials Chemistry, Vol: 21, Pages: 18744-18752, ISSN: 0959-9428
The synthesis of the novel electron-rich pyrroloindacenodithiophene (NIDT) unit is reported. Stille copolymerization of the distannylated NIDT unit, with the electron-deficient dibrominated benzothiadiazole (BT), difluorobenzothiadiazole (ffBT), thienopyrrolodione (TPD) and 1,1[prime or minute]-bithienopyrrolodione (biTPD) units afforded a series of low band gap semiconducting polymers. Initial testing shows promise for the use of these materials as p-type semiconductors in organic field effect transistors (OFETs) with mobilities as high as 0.07 cm2V-1s-1 being measured. These materials have also been tested as the donor polymer in polymer/fullerene bulk heterojunction organic photovoltaics (OPVs) giving maximum efficiencies of 2.5%.
Al-Hashimi M, Labram JG, Watkins S, et al., 2010, Synthesis and Characterization of Fused Pyrrolo[3,2-d:4,5-d′]bisthiazole-Containing Polymers, Organic Letters, Vol: 12, Pages: 5478-5481, ISSN: 1523-7060
Kim YM, Credgingtom DJN, Labram JG, et al., 2010, Combining vacuum deposited with solution processed layers in organic solar cell, Pages: 693-695
Heterojunction cells are the subject of much current research. They can be differentiated by their production processes: solution processing and vacuum processing. Both production processes have advantages and disadvantages. Solution processed devices have the advantages of monodisperity and simple synthesis, but the use of solution processing is limited to soluble conjugated polymers due to their ability to form a smooth film on spin coated materials and the devices are characterised by lower mobilities due to their disordered structures. Vacuum processing can lead to relatively high throughput and sequential stacking of well-defined layers and extraction of exciton diffusion lengths can be performed. Vacuum processed devices, however, tend to suffer from lower efficiencies. Our approach is based on combining vacuum deposited active layers with solution processed layers in organic photovoltaic cells using pentacene and buckminsterfullerene.
Adamopoulos G, Bashir A, Thomas S, et al., 2010, Spray-Deposited Li-Doped ZnO Transistors with Electron Mobility Exceeding 50 cm(2)/Vs, ADVANCED MATERIALS, Vol: 22, Pages: 4764-+, ISSN: 0935-9648
Gelinck G, Heremans P, Nomoto K, et al., 2010, Organic Transistors in Optical Displays and Microelectronic Applications, ADVANCED MATERIALS, Vol: 22, Pages: 3778-3798, ISSN: 0935-9648
Anant P, Lucas NT, Ball JM, et al., 2010, Synthesis and characterization of pyrene-centered oligothiophenes, SYNTHETIC METALS, Vol: 160, Pages: 1987-1993, ISSN: 0379-6779
Smith J, Bashir A, Adamopoulos G, et al., 2010, Air-Stable Solution-Processed Hybrid Transistors with Hole and Electron Mobilities Exceeding 2 cm(2) V-1 s(-1), ADVANCED MATERIALS, Vol: 22, Pages: 3598-+, ISSN: 0935-9648
Zhang W, Smith J, Watkins SE, et al., 2010, Indacenodithiophene Semiconducting Polymers for High-Performance, Air-Stable Transistors, Journal of the American Chemical Society, Vol: 132, Pages: 11437-11439, ISSN: 0002-7863
Smith J, Hamilton R, Qi Y, et al., 2010, The Influence of Film Morphology in High-Mobility Small-Molecule:Polymer Blend Organic Transistors, ADVANCED FUNCTIONAL MATERIALS, Vol: 20, Pages: 2330-2337, ISSN: 1616-301X
Leem D-S, Woebkenberg PH, Huang J, et al., 2010, Micron-scale patterning of high conductivity poly(3,4-ethylendioxythiophene):poly(styrenesulfonate) for organic field-effect transistors, ORGANIC ELECTRONICS, Vol: 11, Pages: 1307-1312, ISSN: 1566-1199
Labram JG, Wöbkenberg PH, Bradley DDC, et al., 2010, Low-voltage ambipolar phototransistors based on a pentacene/PC61BM heterostructure and a self-assembled nano-dielectric, Organic Electronics, Vol: 11, Pages: 1250-1254, ISSN: 1566-1199
Woebkenberg PH, Ishwara T, Nelson J, et al., 2010, TiO2 thin-film transistors fabricated by spray pyrolysis, APPLIED PHYSICS LETTERS, Vol: 96, ISSN: 0003-6951
Smith J, Hamilton R, McCulloch I, et al., 2010, Solution-processed organic transistors based on semiconducting blends, JOURNAL OF MATERIALS CHEMISTRY, Vol: 20, Pages: 2562-2574, ISSN: 0959-9428
Baklar M, Woebkenberg PH, Sparrowe D, et al., 2010, Ink-jet printed p-type polymer electronics based on liquid-crystalline polymer semiconductors, JOURNAL OF MATERIALS CHEMISTRY, Vol: 20, Pages: 1927-1931, ISSN: 0959-9428
Afonina I, Skabara PJ, Vilela F, et al., 2010, Synthesis and characterisation of new diindenodithienothiophene (DITT) based materials, Journal of Materials Chemistry, Vol: 20, Pages: 1112-1116, ISSN: 0959-9428
Three new diindenodithienothiophene (DITT) based materials were synthesised and their electrochemical properties investigated. The HOMO-LUMO gaps were observed to be 3.33, 3.48 and 2.81 eV, respectively. Cyclic voltammetry results indicate increased stability for the alkylated derivatives. The dioxide exhibits strong photoluminescence, giving a photoluminescence quantum yield of 0.72 in solution and 0.14 in the solid state. Hole mobility measurements were carried out on the non-alkylated derivative and the corresponding values were [similar]10-4 cm2 V-1 s-1.
Wobkenberg PH, Labram JG, Swiecicki J, et al., 2010, Ambipolar organic transistors and near-infrared phototransistors based on a solution-processable squarilium dye, Journal of Materials Chemistry, Vol: 20, Pages: 3673-3680, ISSN: 0959-9428
Implementation of organic transistors in low-end, large-volume microelectronics depends, greatly, on the level of performance that can be achieved, but also on the compatibility of the technology with low-cost processing methodologies. Here we examine the suitability of a family of solution-processable zwitterionic molecules, so-called squarilium dyes, for the fabrication of organic ambipolar transistors and their application in (opto)electronic circuits. Ambipolar organic semiconductors and transistors are interesting because they could deliver performance characteristics (i.e. noise margins and signal gain) similar to that of complementary logic, but with the fabrication simplicity associated with unipolar logic (i.e. single semiconductor material and single type of metal electrodes). By designing squarilium dyes with appropriate electrochemical characteristics we demonstrate single-layer organic transistors that exhibit ambipolar charge transport with balanced electron and hole mobilities. By integrating a number of these ambipolar transistors we are also able to demonstrate complementary-like voltage inverters with wide noise margin and high signal gain. Another interesting feature of the squarilium dyes studied here is their strong absorption in the near-infrared (NIR) region of the electromagnetic spectrum. By exploring this interesting property we are able to demonstrate NIR light-sensing ambipolar organic transistors with promising operating characteristics.
Ball JM, Wöbkenberg PH, Colléaux F, et al., 2009, Solution processed low-voltage organic transistors based on self-assembled monolayer gate dielectrics, ISSN: 0277-786X
Reduction in the operating voltage of organic field-effect transistors (OFETs) is sought for their successful implementation into future portable and low-power electronic applications. Here we demonstrate OFETs with operation below 2 V enabled by the use of self-assembled monolayer (SAM) gate dielectrics with high geometrical capacitances. A high surface energy monolayer is chosen to allow processing of small molecule semiconductors from solution. Impedance spectroscopy measurements of metal-insulator-semiconductor devices suggest the geometrical capacitance of the alumina-SAM dielectric can reach ∼1 μF/cm2 when accumulating charge at the semiconductor-insulator interface. Atomic force microscopy images reveal that the glass substrates and the SAM-functionalized aluminum gate electrode display significant roughness. Despite this, mobilities of 0.02 cm2/Vs are demonstrated. These results represent an important step towards low-power solution processable electronics. © 2009 SPIE.
Smith J, Hamilton R, McCulloch I, et al., 2009, High mobility p-channel organic field effect transistors on flexible substrates using a polymer-small molecule blend, SYNTHETIC METALS, Vol: 159, Pages: 2365-2367, ISSN: 0379-6779
Ball JM, Wobkenberg PH, Kooistra FB, et al., 2009, Complementary circuits based on solution processed low-voltage organic field-effect transistors, SYNTHETIC METALS, Vol: 159, Pages: 2368-2370, ISSN: 0379-6779
Adamopoulos G, Bashir A, Woebkenberg PH, et al., 2009, Electronic properties of ZnO field-effect transistors fabricated by spray pyrolysis in ambient air, APPLIED PHYSICS LETTERS, Vol: 95, ISSN: 0003-6951
Ball JM, Woebkenberg PH, Colleaux F, et al., 2009, Solution processed low-voltage organic transistors and complementary inverters, APPLIED PHYSICS LETTERS, Vol: 95, ISSN: 0003-6951
Zhang W, Smith J, Hamilton R, et al., 2009, Systematic Improvement in Charge Carrier Mobility of Air Stable Triarylamine Copolymers, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 131, Pages: 10814-+, ISSN: 0002-7863
Bashir A, Woebkenberg PH, Smith J, et al., 2009, High-Performance Zinc Oxide Transistors and Circuits Fabricated by Spray Pyrolysis in Ambient Atmosphere, ADVANCED MATERIALS, Vol: 21, Pages: 2226-+, ISSN: 0935-9648
Hamilton R, Smith J, Ogier S, et al., 2009, High-Performance Polymer-Small Molecule Blend Organic Transistors, ADVANCED MATERIALS, Vol: 21, Pages: 1166-1171, ISSN: 0935-9648
Hamilton R, Heeney M, Anthopoulos T, et al., 2009, Development of polymer semiconductors for field-effect transistor devices in displays, Organic Electronics: Materials, Processing, Devices and Applications, Pages: 393-429, ISBN: 9781420072907
© 2010 by Taylor & Francis Group, LLC. The increasingly impressive electrical performance of organic semiconductors is driving the development of solution-based printing processes aimed at low cost fabrication of transistor devices. The most immediate application area will most likely be in active matrix displays, where transistors are used in the backplane circuitry, operating basically as an individual pixel switch. In liquid crystal displays (LCDs) and electrophoretic displays (EPDs), the transistor charges both the pixel and storage capacitor, whereas in an organic light-emitting diode display (OLED), the transistor delivers current to the diode element. Most medium and large size LCDs, i.e., monitor and television displays, employ amorphous silicon as the transistor semiconductor (high resolution displays often require polysilicon), with a charge carrier mobility of the order of 0.5 cm2/V s. The EPD effect can tolerate a lower performance from backplane transistors and is hence the most compatible with the performance limitations of organic transistors. As the EPD effect is reflective, the pixel transistor can occupy almost the full area underneath the pixel, in contrast to transmissive display effects such as LCD, where the opaque transistors block light from the backlight and therefore must be as small as possible (i.e., the pixel should have a high aperture ratio) to maximize the efficiency. This means that the EPD transistor width (W) is maximized and can deliver more current per pixel compensating for low mobility semiconductors. As a result, mobility specifications are in the region of 0.01 cm2/V s for a device with low refresh rates, low resolution, and small size. Another favorable aspect of the EPD effect is that once the pixel and storage capacitor is charged, no further power is required to retain the image, i.e., it is bistable. Thus the duty cycle load on the transistor is minimized, and subsequently the devices can potentially have long
Smith J, Hamilton R, Heeney M, et al., 2008, High-performance organic integrated circuits based on solution processable polymer-small molecule blends, APPLIED PHYSICS LETTERS, Vol: 93, ISSN: 0003-6951
Woebkenberg PH, Ball J, Kooistra FB, et al., 2008, Low-voltage organic transistors based on solution processed semiconductors and self-assembled monolayer gate dielectrics, APPLIED PHYSICS LETTERS, Vol: 93, ISSN: 0003-6951
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