High-troughput fabrication of organic nanowire devices with preferential internal alignment and improved performance (original) (raw)
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Nano Letters, 2007
We demonstrate that arrays of nanowires of conjugated polymers can be easily produced by a simple embossing protocol, compatible with very large scale integration technology. The embossing process is shown to have the supplementary virtue to increase the internal degree of order of the nanowires, significantly enhancing their performance. This is applied to the fabrication of nanowire-based devices consisting of a liquid crystalline light-emitting polymer, of a liquid crystalline semiconducting polymer, and of an amorphous conducting polymer, illustrating the versatility and wide applicability of the method.
Organic Nanowire Fabrication and Device Applications
Small, 2014
Organic nanowires (ONWs) are fl exible, stretchable, and have good electrical properties, and therefore have great potential for use in next-generation textile and wearable electronics. Analysis of trends in ONWs supports their great potential for various stretchable and fl exible electronic applications such as fl exible displays and fl exible photovoltaics. Numerous methods can be used to prepare ONWs, but the practical industrial application of ONWs has not been achieved because of the lack of reliable techniques for controlling and patterning of individual nanowires. Therefore, an "individually controllable" technique to fabricate ONWs is essential for practical device applications. In this paper, three types of fabrication methods of ONWs are reviewed: non-alignment methods, massive-alignment methods, and individual-alignment methods. Recent research on electronic and photonic device applications of ONWs is then reviewed. Finally, suggestions for future research are put forward.
ACS Omega, 2021
We present aqueous dispersions of conjugated polymer nanowires (CPNWs) with improved light absorption properties aimed at aqueous-based applications. We assembled films of a donor− acceptor-type conjugated polymer and liquid crystalline 4-noctylbenzoic acid by removing a cosolvent of their mixture solutions, followed by annealing of the films, and then formed aqueous-dispersed CPNWs with an aspect ratio >1000 by dispersing the films under ultrasonication at a basic pH. X-ray and spectroscopy studies showed that the polymer and liquid crystal molecules form independent domains in film assemblies and highly organized layer structures in CPNWs. Our ordered molecular assemblies in films and aqueous dispersions of CPNWs open up a new route to fabricate nanowires of low-band-gap linear conjugated polymers with the absorption maximum at 794 nm remarkably red-shifted from 666 nm of CPNWs prepared by an emulsion process. Our results suggest the presence of semicrystalline polymorphs β 1 and β 2 phases in CPNWs due to long-range π−π stacking of conjugated backbones in compactly organized lamellar structures. The resulting delocalization with a reduced energy bang gap should be beneficial for enhancing charge transfer and energy-conversion efficiencies in aqueous-based applications such as photocatalysis.
Uniaxial alignment of liquid-crystalline conjugated polymers by nanoconfinement
Nano letters, 2007
We demonstrate the uniaxial alignment of a liquid-crystalline conjugated polymer, poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) by means of nanoconfinement during nanoimprinting. The orientation of the conjugated backbones was parallel to the nanolines imprinted into the polymer film. Polarized UV−vis absorption and photoluminescence spectra were measured to quantify the degree of alignment, showing that the polarization ratio and uniaxial molecular order parameter were as high as 66 and 0.97, respectively. The aligned F8BT film was used as the active layer in a PLED, which resulted in polarized electroluminescence with a polarization ratio of 11. Ambipolar PFET in a top-gate configuration with aligned F8BT as the active semiconducting layer showed mobility enhancement when the chains were aligned parallel to the transport direction. Mobility anisotropies for hole and electron transport were 10−15 and 5−7, respectively, for current flow parallel and perpendicular to the alignment direction.
Semiconducting Polymer Nanowires with Highly Aligned Molecules for Polymer Field Effect Transistors
Electronics, 2022
Conjugated polymers have emerged as promising materials for next-generation electronics. However, in spite of having several advantages, such as a low cost, large area processability and flexibility, polymer-based electronics have their own limitations concerning low electrical performance. To achieve high-performance polymer electronic devices, various strategies have been suggested, including aligning polymer backbones in the desired orientation. In the present paper, we report a simple patterning technique using a polydimethylsiloxane (PDMS) mold that can fabricate highly aligned nanowires of a diketopyrrolopyrrole (DPP)-based donor–acceptor-type copolymer (poly (diketopyrrolopyrrole-alt-thieno [3,2-b] thiophene), DPP-DTT) for high-performance field effect transistors. The morphology of the patterns was controlled by changing the concentration of the DPP-based copolymer solution (1, 3, 5 mg mL−1). The molecular alignment properties of three different patterns were observed with a...
Fabrication of Patterned Polymer Nanowire Arrays
ACS Nano, 2011
A method for the large-scale fabrication of patterned organic nanowire (NW) arrays is demonstrated by the use of laser interference patterning (LIP) in conjunction with inductively coupled plasma (ICP) etching. The NW arrays can be fabricated after a short ICP etching of periodic patterns produced through LIP. Arrays of NWs have been fabricated in UV-absorbent polymers, such as PET (polyethylene terephthalate) and Dura film (76% polyethylene and 24% polycarbonate), through laser interference photon ablation and in UV transparent polymers such as PVA (polyvinyl acetate) and PP (polypropylene) through laser interference lithography of a thin layer of photoresist coated atop the polymer surface. The dependence of the structure and morphology of NWs as a function of initial pattern created by LIP and the laser energy dose in LIP is discussed. The absence of residual photoresist atop the NWs in UV-transparent polymers is confirmed through Raman spectroscopy.
Highly Ordered Semiconducting Polymer Arrays for Sensitive Photodetectors
ACS Applied Materials & Interfaces, 2019
Semiconducting conjugated polymers possess attractive optoelectronic properties, low-cost solution processability and inherent mechanical flexibility. However, the device performance is susceptible to the fabrication methods owing to their relative weak intermolecular interaction and inherent conformational and energetic disorder. An efficient fabrication technique for large-scale integration of high-quality polymer architectures is of essential importance in realizing highperformance optoelectronic devices. Here, we report an efficient method for fabrication of polymer nanowire arrays with precise position, smooth surface, homogenous size, high crystallinity and ordered molecular packing. The controllable dewetting dynamics on a template with asymmetric wettability permits the formation of discrete capillary bridges, resulting in the
Nano Letters, 2014
Solution processable semiconducting polymers with excellent film forming capacity and mechanical flexibility are considered among the most progressive alternatives to conventional inorganic semiconductors. However, the random packing of polymer chains and the disorder of the polymer matrix typically result in low charge transport mobilities (10 −5 −10 −2 cm 2 V −1 s −1 ). These low mobilities compromise their performance and development. Here, we present a strategy, by utilizing capillary action, to mediate polymer chain self-assembly and unidirectional alignment on nanogrooved substrates. We designed a sandwich tunnel system separated by functionalized glass spacers to induce capillary action for controlling the polymer nanostructure, crystallinity, and charge transport. Using capillary action, we demonstrate saturation mobilities with average values of 21.3 and 18.5 cm 2 V −1 s −1 on two different semiconducting polymers at a transistor channel length of 80 μm. These values are limited by the source-drain contact resistance, R c . Using a longer channel length of 140 μm where the contact resistance is less important, we measured μ h = 36.3 cm 2 v −1 s −1 . Extrapolating to infinite channel length where R c is unimportant, the intrinsic mobility for poly [4-(4,4-dihexadecyl-4H-cyclopenta[1,2-b:5,4-b′]dithiophen-2-yl)-alt-[1,2,5]thiadiazolo[3,4-c]pyridine] (M n = 140 kDa) at this degree of chain alignment and structural order is μ h ≈ 47 cm 2 v −1 s −1 . Our results create a promising pathway toward high performance, solution processable, and low-cost organic electronics.
Self-Assembled Molecular Nanowires for High-Performance Organic Transistors
ACS Applied Materials & Interfaces
While organic semiconductors provide tantalising possibilities for low-cost, lightweight , flexible electronic devices, their current use in transistors-the fundamental building block-is rather limited as their speed and reliability is not competitive with their inorganic counterparts, and is simply too poor for many practical applications. Through self-assembly, highly ordered nanostructures can be prepared that have more competitive transport characteristics, but no simple, scalable method has been discovered that can produce devices based on such nanostructures. Here we show how transistors of self-assembled molecular nanowires can be fabricated using a scalable, gradient sublimation technique, which have dramatically improved characteristics compared to their thin film counterparts, both in terms of performance and stability. Nanowire devices based on copper phthalocyanine have been fabricated with threshold voltages as low as-2.1 V, high on/off ratios of 10 5 , small sub-threshold swings of 0.9 V/decade and mobilities of 0.6 cm 2 /Vs, and lower trap energies as deduced from temperature-dependent properties-in line with leading organic semiconductors involving more complex fabrication. High-performance transistors manufactured using our scalable deposition technique, compatible with flexible substrates, could enable integrated all-organic chips implementing conventional as well as neuromorphic computation and combining sensors, logic, data storage, drivers and displays.