338 results found
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
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.
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.
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
Ball J, Wöbkenberg PH, Colléaux F, et al., 2008, Solution processed self-assembled monolayer gate dielectrics for low-voltage organic transistors, Pages: 20-25, ISSN: 0272-9172
Low-voltage organic transistors are sought for implementation in high volume low-power portable electronics of the future. Here we assess the suitability of three phosphonic acid based self-assembling molecules for use as ultra-thin gate dielectrics in low-voltage solution processable organic field-effect transistors. In particular, monolayers of phosphonohexadecanoic acid in metal-monolayer-metal type sandwich devices are shown to exhibit low leakage currents and high geometrical capacitance comparable to previously demonstrated self-assembled monolayer (SAM) type dielectrics [1, 2] but with a higher surface energy. The improved surface energy characteristics enable processing of a wider range of organic semiconductors from solution. Transistors based on a number of solution-processed organic semiconductors with operating voltages below 2 V are also demonstrated. © 2009 Materials Research Society.
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
Woebkenberg PH, Bradley DDC, Kronholm D, et al., 2008, High mobility n-channel organic field-effect transistors based on soluble C-60 and C-70 fullerene derivatives, SYNTHETIC METALS, Vol: 158, Pages: 468-472, ISSN: 0379-6779
Wobkenberg PH, Ball J, Bradley DDC, et al., 2008, Fluorine containing C-60 derivatives for high-performance electron transporting field-effect transistors and integrated circuits, APPLIED PHYSICS LETTERS, Vol: 92, ISSN: 0003-6951
Campoy-Quiles M, Ferenczi T, Agostinelli T, et al., 2008, Morphology evolution via self-organization and lateral and vertical diffusion in polymer: fullerene solar cell blends, NATURE MATERIALS, Vol: 7, Pages: 158-164, ISSN: 1476-1122
Anthopoulos TD, Woebkenberg PH, Bradley DDC, 2008, Light-sensing ambipolar organic transistors for optoelectronic applications, Conference on Organic Optoelectronics and Photonics III, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
Pang H, Vilela F, Skabara PJ, et al., 2007, Advantageous 3D ordering of pi-conjugated systems: A new approach towards efficient charge transport any direction, ADVANCED MATERIALS, Vol: 19, Pages: 4438-+, ISSN: 0935-9648
Nguyen TD, Sheng Y, Wohlgenannt M, et al., 2007, On the role of hydrogen in organic magnetoresistance: A study of C-60 devices, SYNTHETIC METALS, Vol: 157, Pages: 930-934, ISSN: 0379-6779
Anthopoulos TD, 2007, Electro-optical circuits based on light-sensing ambipolar organic field-effect transistors, APPLIED PHYSICS LETTERS, Vol: 91, ISSN: 0003-6951
Smits ECP, Setayesh S, Anthopoulos TD, et al., 2007, Near-infrared light-emitting ambipolar organic field-effect transistors, ADVANCED MATERIALS, Vol: 19, Pages: 734-+, ISSN: 0935-9648
Cabanillas-Gonzalez J, Virgili T, Gambetta A, et al., 2007, Subpicosecond photoinduced Stark spectroscopy in fullerene-based devices, PHYSICAL REVIEW B, Vol: 75, ISSN: 1098-0121
Anthopoulos TD, Singh B, Marjanovic N, et al., 2006, High performance n-channel organic field-effect transistors and ring oscillators based on C60 fullerene films, Applied Physics Letters, Vol: 89
de Haas MP, Warman JM, Anthopoulos TD, et al., 2006, The mobility and decay kinetics of charge carriers in pulse-ionized microcrystalline PCBM powder, ADVANCED FUNCTIONAL MATERIALS, Vol: 16, Pages: 2274-2280, ISSN: 1616-301X
Warman JM, de Haas MP, Anthopoulos TD, et al., 2006, The negative effect of high-temperature annealing on charge-carrier lifetimes in microcrystalline PCBM, Advanced Materials, Vol: 18, Pages: 2294-2298
Warman JM, de Haas MP, Anthopoulos TD, et al., 2006, The negative effect of high-temperature annealing on charge-carrier lifetimes in microcrystalline PCBM, ADVANCED MATERIALS, Vol: 18, Pages: 2294-+, ISSN: 0935-9648
Anthopoulos TD, Setayesh S, Smits E, et al., 2006, Air-stable complementary-like circuits based on organic ambipolar transistors, ADVANCED MATERIALS, Vol: 18, Pages: 1900-+, ISSN: 0935-9648
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