Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Penn Researchers Make Flexible, Low-voltage Circuits Using Nanocrystals

Flexible circuit fabricated in the Kagan lab. (Photo: David Kim and Yuming Lai)
Flexible circuit fabricated in the Kagan lab.

(Photo: David Kim and Yuming Lai)

Abstract:
Electronic circuits are typically integrated in rigid silicon wafers, but flexibility opens up a wide range of applications. In a world where electronics are becoming more pervasive, flexibility is a highly desirable trait, but finding materials with the right mix of performance and manufacturing cost remains a challenge.

Penn Researchers Make Flexible, Low-voltage Circuits Using Nanocrystals

Philadelphia, PA | Posted on November 27th, 2012

Now a team of researchers from the University of Pennsylvania has shown that nanoscale particles, or nanocrystals, of the semiconductor cadmium selenide can be "printed" or "coated" on flexible plastics to form high-performance electronics.

The research was led by David Kim, a doctoral student in the Department of Materials Science and Engineering in Penn's School of Engineering and Applied Science; Yuming Lai, a doctoral student in the Engineering School's Department of Electrical and Systems Engineering; and professor Cherie Kagan, who has appointments in both departments as well as in the School of Arts and Sciences' Department of Chemistry. Benjamin Diroll, a doctoral student in chemistry, and Penn Integrates Knowledge Professor Christopher Murray of Materials Science and of Chemistry also collaborated on the research.

Their work was published in the journal Nature Communications.

"We have a performance benchmark in amorphous silicon, which is the material that runs the display in your laptop, among other devices," Kagan said. "Here, we show that these cadmium selenide nanocrystal devices can move electrons 22 times faster than in amorphous silicon."

Besides speed, another advantage cadmium selenide nanocrystals have over amorphous silicon is the temperature at which they are deposited. Whereas amorphous silicon uses a process that operates at several hundred degrees, cadmium selenide nanocrystals can be deposited at room temperature and annealed at mild temperatures, opening up the possibility of using more flexible plastic foundations.

Another innovation that allowed the researchers to use flexible plastic was their choice of ligands, the chemical chains that extend from the nanocrystals' surfaces and helps facilitate conductivity as they are packed together into a film.

"There have been a lot of electron transport studies on cadmium selenide, but until recently we haven't been able to get good performance out of them," Kim said. "The new aspect of our research was that we used ligands that we can translate very easily onto the flexible plastic; other ligands are so caustic that the plastic actually melts."

Because the nanocrystals are dispersed in an ink-like liquid, multiple types of deposition techniques can be used to make circuits. In their study, the researchers used spincoating, where centrifugal force pulls a thin layer of the solution over a surface, but the nanocrystals could be applied through dipping, spraying or ink-jet printing as well.

On a flexible plastic sheet a bottom layer of electrodes was patterned using a shadow mask — essentially a stencil — to mark off one level of the circuit. The researchers then used the stencil to define small regions of conducting gold to make the electrical connections to upper levels that would form the circuit. An insulating aluminum oxide layer was introduced and a 30-nanometer layer of nanocrystals was coated from solution. Finally, electrodes on the top level were deposited through shadow masks to ultimately form the circuits.

"The more complex circuits are like buildings with multiple floors," Kagan said. "The gold acts like staircases that the electrons can use to travel between those floors."

Using this process, the researchers built three kinds of circuits to test the nanocrystals performance for circuit applications: an inverter, an amplifier and a ring oscillator.

"An inverter is the fundamental building block for more complex circuits," Lai said. "We can also show amplifiers, which amplify the signal amplitude in analog circuits, and ring oscillators, where ‘on' and ‘off' signals are properly propagating over multiple stages in digital circuits."

"And all of these circuits operate with a couple of volts," Kagan said. "If you want electronics for portable devices that are going to work with batteries, they have to operate at low voltage or they won't be useful."

With the combination of flexibility, relatively simple fabrication processes and low power requirements, these cadmium selenide nanocrystal circuits could pave the way for new kinds of devices and pervasive sensors, which could have biomedical or security applications.

"This research also opens up the possibility of using other kinds of nanocrystals, as we've shown the materials aspect is not a limitation any more," Kim said.

The research was supported by the U.S. Department of Energy and the National Science Foundation.

####

For more information, please click here

Contacts:
Evan Lerner

215-573-6604

Copyright © University of Pennsylvania

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Iran to Hold 3rd Int'l Engineering Materials, Metallurgy Conference October 25th, 2014

Haydale Secures Exclusive Development and Supply Agreement with Tantec A/S: New reactors to be built and commissioned by Tantec A/S represent another step forward towards the commercialisation of graphene October 24th, 2014

QuantumWise guides the semiconductor industry towards the atomic scale October 24th, 2014

SUNY Polytechnic Institute Invites the Public to Attend its Popular Statewide 'NANOvember' Series of Outreach and Educational Events October 23rd, 2014

Law enforcement/Anti-Counterfeiting/Security/Loss prevention

Superconducting circuits, simplified: New circuit design could unlock the power of experimental superconducting computer chips October 18th, 2014

IRLYNX and CEA-Leti to Streamline New CMOS-based Infrared Sensing Modules Dedicated to Human-activities Characterization October 15th, 2014

Nanoparticles give up forensic secrets October 2nd, 2014

Flexible Electronics

Crumpled graphene could provide an unconventional energy storage: Two-dimensional carbon “paper” can form stretchable supercapacitors to power flexible electronic devices October 4th, 2014

'Pixel' engineered electronics have growth potential: Rice, Oak Ridge, Vanderbilt, Penn scientists lead creation of atom-scale semiconducting composites September 29th, 2014

'Greener,' low-cost transistor heralds advance in flexible electronics September 24th, 2014

Govt.-Legislation/Regulation/Funding/Policy

Novel Rocket Design Flight Tested: New Rocket Propellant and Motor Design Offers High Performance and Safety October 23rd, 2014

Strengthening thin-film bonds with ultrafast data collection October 23rd, 2014

Brookhaven Lab Launches Computational Science Initiative:Leveraging computational science expertise and investments across the Laboratory to tackle "big data" challenges October 22nd, 2014

Bipolar Disorder Discovery at the Nano Level: Tiny structures found in brain synapses help scientists better understand disorder October 22nd, 2014

Chip Technology

QuantumWise guides the semiconductor industry towards the atomic scale October 24th, 2014

Strengthening thin-film bonds with ultrafast data collection October 23rd, 2014

NIST offers electronics industry 2 ways to snoop on self-organizing molecules October 22nd, 2014

Materials for the next generation of electronics and photovoltaics: MacArthur Fellow develops new uses for carbon nanotubes October 21st, 2014

Nanomedicine

NYU Researchers Break Nano Barrier to Engineer the First Protein Microfiber October 23rd, 2014

Iranian Scientists Apply Nanotechnology to Produce Surgery Suture October 23rd, 2014

RF Heating of Magnetic Nanoparticles Improves the Thawing of Cryopreserved Biomaterials October 23rd, 2014

Sopping up proteins with thermosponges: Researchers develop novel nanoparticle platform that proves effective in delivering protein-based drugs October 22nd, 2014

Sensors

MEMS & Sensors Technology Showcase: Finalists Announced for MEMS Executive Congress US 2014 October 23rd, 2014

Journal Nanotechnology Progress International (JONPI), 2014, Volume 5, Issue 1, pp 1-24 October 22nd, 2014

Imaging electric charge propagating along microbial nanowires October 20th, 2014

Graphenea opens US branch October 16th, 2014

Discoveries

QuantumWise guides the semiconductor industry towards the atomic scale October 24th, 2014

Iranian, Malaysian Scientists Study Nanophotocatalysts for Water Purification October 23rd, 2014

Nanoparticle technology triples the production of biogas October 23rd, 2014

Strengthening thin-film bonds with ultrafast data collection October 23rd, 2014

Announcements

Iran to Hold 3rd Int'l Engineering Materials, Metallurgy Conference October 25th, 2014

Haydale Secures Exclusive Development and Supply Agreement with Tantec A/S: New reactors to be built and commissioned by Tantec A/S represent another step forward towards the commercialisation of graphene October 24th, 2014

QuantumWise guides the semiconductor industry towards the atomic scale October 24th, 2014

Strengthening thin-film bonds with ultrafast data collection October 23rd, 2014

Printing/Lithography/Inkjet/Inks

3DXNano™ ESD Carbon Nanotube 3D Printing Filament - optimized for demanding 3D printing applications in the semi-con and electronics industry October 16th, 2014

Aculon NanoClear Stencil Solution Wins 2014 Global Technology Award at SMTAI October 12th, 2014

Fast, cheap nanomanufacturing: Arrays of tiny conical tips that eject ionized materials could fabricate nanoscale devices cheaply October 4th, 2014

'Greener,' low-cost transistor heralds advance in flexible electronics September 24th, 2014

NanoNews-Digest
The latest news from around the world, FREE





  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE