Featured Research

from universities, journals, and other organizations

Golden potential for gold thin films

Date:
April 27, 2012
Source:
DOE/Lawrence Berkeley National Laboratory
Summary:
Researchers have directed the first self-assembly of nanoparticles into multi-layered thin films of gold that are device-ready for potential applications in computer memory storage, energy harvesting, energy storage, remote-sensing, catalysis, light management and plasmonics.

Berkeley Lab researchers have developed a relatively simple and inexpensive technique for directing the self-assembly of nanoparticles into device-ready thin films with microdomains of lamellar (left) or cylindrical morphologies.
Credit: Courtesy of Ting Xu group

Scientists with the Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley have directed the first self-assembly of nanoparticles into device-ready materials. Through a relatively easy and inexpensive technique based on blending nanoparticles with block co-polymer supramolecules, the researchers produced multiple-layers of thin films from highly ordered one-, two- and three-dimensional arrays of gold nanoparticles. Thin films such as these have potential applications for a wide range of fields, including computer memory storage, energy harvesting, energy storage, remote-sensing, catalysis, light management and the emerging new field of plasmonics.

Related Articles


"We've demonstrated a simple yet versatile supramolecular approach to control the 3-D spatial organization of nanoparticles with single particle precision over macroscopic distances in thin films," says polymer scientist Ting Xu, who led this research. "While the thin gold films we made were wafer-sized, the technique can easily produce much larger films, and it can be used on nanoparticles of many other materials besides gold."

Xu holds joint appointments with Berkeley Lab's Materials Sciences Division and UC Berkeley's Departments of Materials Sciences and Engineering, and Chemistry. She is the corresponding author of a paper describing this research in the journal Nano Letters titled "Nanoparticle Assemblies in Thin Films of Supramolecular Nanocomposites." Co-authoring the paper were Joseph Kao, Peter Bai, Vivian Chuang, Zhang Jiang and Peter Ercius.

Nanoparticles can be thought of as artificial atoms with unique optical, electrical and mechanical properties. If nanoparticles can be coaxed into routinely assembling themselves into complex structures and hierarchical patterns, similar to what nature does with proteins, devices a thousand times smaller than those of today's microtechnologies could be mass-produced.

Xu and her research group have been advancing towards this goal for the past decade. In a study earlier this year, they were able to induce rod-shaped semiconductor nanocrystals to self-assemble into one-, two- and even three-dimensional macroscopic structures. With this latest application of their methods to thin films, they have moved into the realm of material forms that are required for device fabrication and are well-suited for scalable nanomanufacturing.

"This is the first time that 2-D nanoparticle assembly, similar to those obtained using DNA linkers and controlled solvent evaporation, can be clearly achieved in multi-layers in supramolecule-based nanocomposite thin films," Xu says. "Our supramolecular approach does not require chemical modification to any of the components in the composite system and, in addition to providing a means of building nanoparticle-based devices, should also provide a powerful platform for studying nanoparticle structure-property correlations."

The technique developed by Xu and her colleagues uses solutions of block co-polymer supramolecules to direct the self-assembly of nanoparticles. A supramolecule is a group of molecules that act as a single molecule able to perform a specific set of functions. Block copolymers are long sequences or "blocks" of one type of monomer bound to blocks of another type of monomer that have an innate ability to self-assemble into well-defined arrays of nano-sized structures over macroscopic distances.

"Block copolymer supramolecules self-assemble and form a wide range of morphologies that feature microdomains typically a few to tens of nanometers in size," Xu says. "As their size is comparable to that of nanoparticles, the microdomains of block copolymer supramolecules provide an ideal structural framework for the co-self-assembly of nanoparticles."

In this latest study, Xu and her colleagues incorporated gold nanoparticles into solutions of block co-polymer supramolecules to form films that ranged in thickness between 100 to 200 nanometers. The nanocomposite films featured microdomains in one of two common morphologies -- lamellar or cylindrical. For the lamellar microdomains, the nanoparticles formed hexagonally-packed 2-D sheets that were stacked into multiple layers parallel to the surface. For the cylindrical microdomains, the nanoparticles formed 1-D chains (single particle width) that were packed into distorted hexagonal lattices in parallel orientation with the surface.

"Upon incorporation of nanoparticles, the block co-polymer supramolecules experience conformational changes, resulting in entropy that determines the placement and distribution of the nanoparticles, as well as the overall morphology of the nanocomposite thin films," Xu says. "Our results indicate that it should be possible to generate highly-ordered lattices of nanoparticles within block co-polymer microdomains and obtain 3-D hierarchical assemblies of nanoparticles with precise structural control."

The inter-particle distance between gold nanoparticles in the 1-D chains and the 2-D sheets was 8 to 10 nanometers, which raises intriguing possibilities with regards to plasmonics, the phenomenon by which a beam of light is confined in ultra-cramped spaces. Plasmonic technology holds great promise for superfast computers and optical microscopy, among other applications. However, a major challenge for developing plasmonics has been the difficulty of fabricating metamaterials with noble metal nanoparticles such as gold.

"Our gold thin films display strong plasmonic coupling along the inter-particle spacing in the 1-D chains and 2-D sheets respectively," Xu says. "We should therefore be able to use these films to investigate unique plasmonic properties for next-generation electronic and photonic devices. Our supramolecular technique might also be used to fabricate plasmonic metamaterials."

This research was supported by the U.S. Department of Energy Office of Science.


Story Source:

The above story is based on materials provided by DOE/Lawrence Berkeley National Laboratory. Note: Materials may be edited for content and length.


Journal Reference:

  1. Joseph Kao, Peter Bai, Vivian P. Chuang, Zhang Jiang, Peter Ercius, Ting Xu. Nanoparticle Assemblies in Thin Films of Supramolecular Nanocomposites. Nano Letters, 2012; 120405143117000 DOI: 10.1021/nl300999u

Cite This Page:

DOE/Lawrence Berkeley National Laboratory. "Golden potential for gold thin films." ScienceDaily. ScienceDaily, 27 April 2012. <www.sciencedaily.com/releases/2012/04/120427142143.htm>.
DOE/Lawrence Berkeley National Laboratory. (2012, April 27). Golden potential for gold thin films. ScienceDaily. Retrieved November 25, 2014 from www.sciencedaily.com/releases/2012/04/120427142143.htm
DOE/Lawrence Berkeley National Laboratory. "Golden potential for gold thin films." ScienceDaily. www.sciencedaily.com/releases/2012/04/120427142143.htm (accessed November 25, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Tuesday, November 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Who Will Failed Nuclear Talks Hurt Most?

Who Will Failed Nuclear Talks Hurt Most?

Reuters - Business Video Online (Nov. 25, 2014) With no immediate prospect of sanctions relief for Iran, and no solid progress in negotiations with the West over the country's nuclear programme, Ciara Lee asks why talks have still not produced results and what a resolution would mean for both parties. Video provided by Reuters
Powered by NewsLook.com
Flying Enthusiast Converts Real-Life Aircraft Cockpit Into Simulator

Flying Enthusiast Converts Real-Life Aircraft Cockpit Into Simulator

Reuters - Innovations Video Online (Nov. 25, 2014) A virtual flying enthusiast converts parts of a written-off Airbus aircraft into a working flight simulator in his northern Slovenian home. Jim Drury reports. Video provided by Reuters
Powered by NewsLook.com
Car Park Solution for Flexible Green Energy

Car Park Solution for Flexible Green Energy

Reuters - Innovations Video Online (Nov. 24, 2014) A British solar power start-up says that by covering millions of existing car park spaces around the UK with flexible solar panels, the country's power problems could be solved. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Microsoft Adds Robot Guards, Ushers In Sci-Fi Apocalypse

Microsoft Adds Robot Guards, Ushers In Sci-Fi Apocalypse

Newsy (Nov. 23, 2014) Microsoft has robotic security guards working at its Silicon Valley Campus. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins