Tunable Band Alignment with Unperturbed Carrier Mobility of On-Surface Synthesized Organic Semiconducting Wires (original) (raw)

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.

Light-triggered self-construction of supramolecular organic nanowires as metallic interconnects

Nature Chemistry, 2012

The construction of soft and processable organic material able to display metallic conduction properties-a large density of freely moving charges-is a major challenge for electronics. Films of doped conjugated polymers are widely used as semiconductor devices, but metallic-type transport in the bulk of such materials remains extremely rare. On the other hand, single-walled carbon nanotubes can exhibit remarkably low contact resistances with related large currents, but are intrinsically very difficult to isolate and process. Here, we describe the self-assembly of supramolecular organic nanowires between two metallic electrodes, from a solution of triarylamine derivative, under the simultaneous action of light and electric field triggers. They exhibit a combination of large conductivity values (>5 3 10 3 S m 21 ) and a low interface resistance (<2 3 10 24 V m). Moreover, the resistance of nanowires in series with metal interfaces systematically decreases when the temperature is lowered to 1.5 K, revealing an intrinsic metallic behaviour. F or more than three decades 1,2 , remarkable improvements have been made to the performances of conjugated organic polymers as active semiconducting components 3-5 . For example, intrinsic charge transport along polymer chains has been enhanced by means of controlled chemical or electrochemical doping 6 , while crystal engineering 7,8 has reduced the incoherent interchain hopping regime, yielding much higher mobilities for the charge carriers. However, soft interconnects with even better conductivities and limited interface resistance values with metals are needed for low-power plastic electronics, in particular for the miniaturization of devices at the nanoscale.

Ubiquitous organic molecule-based free-standing nanowires with ultra-high aspect ratios

Nature Communications, 2021

The critical dimension of semiconductor devices is approaching the single-nm regime, and a variety of practical devices of this scale are targeted for production. Planar structures of nano-devices are still the center of fabrication techniques, which limit further integration of devices into a chip. Extension into 3D space is a promising strategy for future; however, the surface interaction in 3D nanospace make it hard to integrate nanostructures with ultrahigh aspect ratios. Here we report a unique technique using high-energy charged particles to produce free-standing 1D organic nanostructures with high aspect ratios over 100 and controlled number density. Along the straight trajectory of particles penetrating the films of various sublimable organic molecules, 1D nanowires were formed with approximately 10~15 nm thickness and controlled length. An all-dry process was developed to isolate the nanowires, and planar or coaxial heterojunction structures were built into the nanowires. E...

High-troughput fabrication of organic nanowire devices with preferential internal alignment and improved performance

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.

High-Throughput Fabrication of Organic Nanowire Devices with Preferential Internal Alignment and Improved Performance

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.

Π Band Dispersion along Conjugated Organic Nanowires Synthesized on a Metal Oxide Semiconductor

Journal of the American Chemical Society, 2016

Surface-confined dehalogenation reactions are versatile bottom-up approaches for the synthesis of carbon-based nanostructures with predefined chemical properties. However, for devices generally requiring low-conductivity substrates, potential applications are so far severely hampered by the necessity of a metallic surface to catalyze the reactions. In this work we report the synthesis of ordered arrays of poly(p-phenylene) chains on the surface of semiconducting TiO2(110) via a dehalogenative homocoupling of 4,4″-dibromoterphenyl precursors. The supramolecular phase is clearly distinguished from the polymeric one using low-energy electron diffraction and scanning tunneling microscopy as the substrate temperature used for deposition is varied. X-ray photoelectron spectroscopy of C 1s and Br 3d core levels traces the temperature of the onset of dehalogenation to around 475 K. Moreover, angle-resolved photoemission spectroscopy and tight-binding calculations identify a highly dispersiv...

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.

Positioning and joining of organic single-crystalline wires

Nature Communications, 2015

Organic single-crystal, one-dimensional materials can effectively carry charges and/or excitons due to their highly ordered molecule packing, minimized defects and eliminated grain boundaries. Controlling the alignment/position of organic single-crystal one-dimensional architectures would allow on-demand photon/electron transport, which is a prerequisite in waveguides and other optoelectronic applications. Here we report a guided physical vapour transport technique to control the growth, alignment and positioning of organic single-crystal wires with the guidance of pillar-structured substrates. Submicrometre-wide, hundreds of micrometres long, highly aligned, organic single-crystal wire arrays are generated. Furthermore, these organic single-crystal wires can be joined within controlled angles by varying the pillar geometries. Owing to the controllable growth of organic single-crystal one-dimensional architectures, we can present proof-of-principle demonstrations utilizing joined wi...