A Single Polymer Nanowire Photodetector

Abstract

Semiconducting nanowires and nanotubes are an emerging class of 1D nanostructures that represent attractive building blocks for nanoscale electronic and photonic devices. For example, inorganic semiconductor nanowires [1][2][3] and carbon nanotubes, [4] show great promise for nanoelectronic devices and integrated nanosystems because they can function both as device components for logic, memory, and sensing applications and also as interconnects. Inorganic semiconductor nanowires are also attracting increasing research interest as building blocks for integrated nanophotonic systems, since they can function as subwavelength optical waveguides, emissive devices, and photodetectors. [1][2][3][5][6][7][8][9][10][11][12] With respect to the latter, photoconductance measurements have recently been reported for a range of single inorganic nanowire devices: InP, [5] ZnO, [6] GaN, [7] and Si, [8] as well as for carbon-nanotube devices.[13]While inorganic nanowires and carbon nanotubes have been explored in depth, the challenge of controlled fabrication of 1D nanostructures based on organic molecular materials suitable for integrated (opto)electronic applications has yet to be as comprehensively addressed. In particular, semiconducting polymers are attractive materials due to their chemically tunable optical and electronic properties, as well as their facility for solution processing. [14,15] 1D nanostructures fabricated from such polymers have been the subject of recent research with regard to their physical, chemical, electronic, and photonic properties. [16][17][18][19][20] However, demonstration of viable polymer nanowire technologies will require the development of reliable methods for the production of such structures with good control over critical parameters such as diameter, length, morphology, and chemical composition. Recently, a new method for the formation of organic nanotubes and nanowires through the wetting of porous anodized alumina membranes has been reported. [20] This method of template wetting using solution-based or molten material does not require specialized apparatus and is broadly applicable across a wide range of organic materials, including small molecules, oligomers, polymers, blends, and multicomponent solutions.[20]In this work, we demonstrate that solution-assisted template wetting may be successfully exploited for high-yield controlled synthesis of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(bithiophene)] (F8T2) nanowires. Following liberation from the template and dispersion, our method produces discrete nanowires with average lengths of 15 lm and mean diameters of 200 nm. We report on the electrical characteristics of singlenanowire devices and, further, on the use of single F8T2 nanowires in photoconductivity-based photodetectors. To date, there have been relatively few reports on photoconductivity in 1D polymer nanostructures; for example, Kim and coworkers have reported photoconductance in single bilayer nanotubes comprising poly-(p-phenylenevinylene) (PPV) nanotube cores and carbonized PP...

Anomalous Transient Photocurrent

“…The on/off ratio increases with the light intensity, and its maximum value observed in our experiments is approximately 10 3 . Meanwhile, the photoresponsivity demonstrates an inverse behaviour, and changes from 10 -1 to 10 -4 A/W, which is comparable to that of the most advanced organic polymer photodetectors for visible region (Hamilton & Kanicki, 2004;Narayan & Singh, 1999;O'Brien et al, 2006;Xu et al, 2004). It is notable that the ITO/BDTDA/Al cells produce a photocurrent even at V bias = 0 V, due to the potential difference of the electrodes, specifically ITO (4.8 eV) and Al (4.3 eV).…”

Fluorene-based macromolecular nanostructures and nanomaterials for organic (opto)electronics

“…In the last two decades, various functions of plastic devices have been demonstrated, including polymer light-emitting diodes (PLEDs) [4,5] for commercial flat panel displays and white solid lighting sources, polymer solar cells (PSCs) [6,7], polymer thin-film transistors [8][9][10][11], polymer lasers [12][13][14][15], polymer photodetectors [16][17][18][19], polymer memory for information storage [20][21][22][23][24][25] and others [26][27][28]. In this area, the basic open question pertaining to commercialization is to fabricate low-cost, stable and high-performance thin-film devices.…”

“…AAO templates are another simple, low-cost and effective method for one-dimensional nanostructures with the special apparatus to generate PFs nanowires that were reported by Redmond and coworkers [17,61,[252][253][254][255]. A representative PF-19 (F8T2) nanowire has an average length of 15 μm and diameter of 200 nm.…”

3-D InGaAs/GaAs Helical Nanobelts for Optoelectronic Devices

“…However, shrinking device size from conventional microelectronics dimensions becomes increasingly difficult due to the limits of standard photolithography and the loss of signal inherent in smaller sensor area. Nanoscale photodetectors have been previously demonstrated using 1-D nanostructures such as a single as-synthesized silicon nanowire (NW) (O'brien et al 2006;Gu et al 2005) or nanotube (NT) (Wei et al 2006) though reduced surface area can negatively affect the signal-to-noise ratio. A nanoscale avalanche photodiode was developed to amplify the single photon detection efficiency Hayden et al 2006).…”