Navigation Links
Nanowires for the electronics and optoelectronics of the future

This release is available in French and German.

Organic semiconductors are very promising candidates as starting materials for the manufacture of cheap, large area and flexible electronic components such as transistors, diodes and sensors on a scale ranging from micro to nano. A condition for success in achieving this goal is the ability to join components together with electrically conducting links in other words, to create an electronic circuit. Empa scientists have developed a new method which allows them to create simple networks of organic nanowires.

The origin: an EU project called PHODYE

When Spanish physicist Angel Barranco returned to Valencia after a three year research stint at Empa, he initiated the EU project PHODYE with, among others, his old Empa colleagues. The aim is to develop highly sensitive gas sensors, for monitoring road vehicle emissions, for example, or for providing laboratory staff and mine workers with an early warning of the presence of poisonous substances. The sensors are based on fluorescing thin films which change color and fluoresce on contact with certain gas molecules.

"We were thinking in terms of a sort of electronic key for security applications, which would only react to certain optical conditions," explains Empa physicist Pierangelo Groening. Necessary for this are transparent, strongly fluorescing thin films, so Groening and Barranco developed a plasma-deposition process in order to store fluorescing dye molecules such as metallo-proyphins, perylenes and phthalocyanines unmodified and at high concentrations in SiO2 or TiO2 layers.

It soon became apparent that if certain gas molecules deposited on dye particles in the thin films, then these fluoresced at different wavelengths and the thin film changed color as a result. If different dyes are used then the gases which are toxic to humans can be detected at very low concentrations.

A surprisingly wide range of uses

However, for many sensor applications it is important that the response time be as short as possible, something which is hardly possible with compact plasma dye layers. It is, on the other hand, possible with layers which have very a porous structure, resembling the nap of a nanometer-scale carpet. Scientists hope to derive further benefits from such layers because they increase the area onto which the gas molecules to be detected can adsorb, and also shorten the diffusion distances, allowing the sensor to respond faster. Physicist Ana Borras thereupon developed a new vacuum deposition process for synthesizing organic nanowires.

In the meantime the Empa researchers made progress, learning how to manufacture nanowires with very widely varying characteristics by appropriately selecting the starting molecule and the experimental conditions. Nanowires of metallo-phthalocyanine molecules have diameters of a mere 10 to 50 nanometers and a length of up to 100 microns. What is unusual and unexpected about the new method is that by exactly controlling the substrate temperature, molecule flow and substrate treatment, the organic nanowires develop a previously unattained, perfectly monocrystalline structure.

Immediately after the first studies were made with the electron microscope it was clear to Groening that the new process could not only provide nanowires for the gas sensors but also make it possible to create complex "nanowire electric circuits" for electronic and optoelectronic applications such as solar cells, transistors and diodes. This is because the different types of nanowires can be combined as required to form networks with widely varying properties, as Groening and coworkers report in the scientific journal Advanced Materials and elsewhere.

The trick to achieving this lies in a second step in which the nanowires growing on the surface are "decorated" with silver nanoparticles by a sputter-coating process. A target, in this case a piece of solid silver, is bombarded with energetic ions, knocking off silver atoms which enter the gas phase and are deposited onto the nanowires. In a final step, the Empa team now grow more nanowires which, thanks to the silver particles, are in electrical contact with the original wires the basis of an electrical circuit on the nanometer scale.

The first step from microelectronics to nanoelectronics

The first electrical conductivity measurements, made with the help of a four-tip scanning tunnel microscope in ultra high vacuum, exceeded the most optimistic expectations the material is of an unusually high quality. "This opens up the possibility of soon being able to manufacture organic semiconductor materials," says Groening confidently. "And that, too, using a simple and economic process." In the meantime the researchers have successfully synthesized increasingly more complex structures of nanowires, and managed to link these together using a good deal of skill and a sure touch.

Take, for example, nanowires consisting of sections made with different starting molecules. If these molecules can transport either only positive or only negative charges, then a diode is created which allows current to flow in one direction alone. Groening speculates that it is quite possible that one day components for nanolectronics and nanophotonics will be made using this technique.


Contact: Sabine Voser
Swiss Federal Laboratories for Materials Testing and Research (EMPA)

Related biology technology :

1. Copper nanowires enable bendable displays and solar cells
2. Researchers use improved nanogenerators to power sensors based on zinc oxide nanowires
3. Trapping sunlight with silicon nanowires
4. New silicon-germanium nanowires could lead to smaller, more powerful electronic devices
5. Dip ordinary paper into ink infused with nanotubes and nanowires to create an instant battery
6. Nanowires key to future transistors, electronics
7. Understanding mechanical properties of silicon nanowires paves way for nanodevices
8. Penn study: Transforming nanowires into nano-tools using cation exchange reactions
9. Harvard scientists bend nanowires into 2-D and 3-D structures
10. Evidence of macroscopic quantum tunneling detected in nanowires
11. Self-assembled nanowires could make chips smaller and faster
Post Your Comments:
Related Image:
Nanowires for the electronics and optoelectronics of the future
(Date:11/27/2015)... /PRNewswire/--  Mallinckrodt plc (NYSE: MNK ), a ... closed the sale of its global contrast media and ... in a transaction valued at approximately $270 million. The ... total of approximately 1,000 employees spread across the globe, ... area. This entire workforce and the manufacturing ...
(Date:11/26/2015)... 26, 2015 ... Accutest Research Laboratories, a leading independent ... (CRO), has formed a strategic partnership ... Temple Health for joint work on ... ) , --> ...
(Date:11/25/2015)... ANNAPOLIS, Md. , Nov. 25, 2015  PharmAthene, ... of Directors has adopted a stockholder rights plan (Rights ... its net operating loss carryforwards (NOLs) under Section 382 ... --> --> PharmAthene,s use of its ... an "ownership change" as defined in Section 382 of ...
(Date:11/25/2015)... HOLLISTON, Mass. , Nov. 25, 2015 ... HART ), a biotechnology company developing bioengineered organ implants ... McGorry will present at the LD Micro "Main ... 2:30 p.m. PT. The presentation will be webcast live ... Management will also be available at the conference for ...
Breaking Biology Technology:
(Date:10/26/2015)... 2015  Delta ID Inc., a company focused on ... PC devices, announced its ActiveIRIS® technology powers the iris ... launched by NTT DOCOMO, INC in Japan ... smartphone to include iris recognition technology, after a very ... in May 2015, world,s first smartphone to have this ...
(Date:10/23/2015)... GOLETA, California , October 23, 2015 ... Instruments (SMI) announce a mobile plug and play integration ... interactive real-world tasks SensoMotoric Instruments (SMI) ... established wearable solutions for eye tracking and physiological data ... with SMI Eye Tracking Glasses 2w and ...
(Date:10/22/2015)... -- Synaptics (NASDAQ: SYNA ), a leading developer of human interface ... 30, 2015. --> --> ... percent over the comparable quarter last year to $470.0 million. Net ... or $0.62 per diluted share. --> ... fiscal 2016 grew 39 percent over the prior year period to ...
Breaking Biology News(10 mins):