Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Single-crystal films could advance solar cells

Amorphous silicon, deposited on a porous template fills the empty spaces. Laser heating melts the deposit and the top few microns of the silicon substrate. In a few nanoseconds the melted silicon recrystallizes. The substrate acts as a seed crystal for the material above, causing it to crystallize with the same alignment. This makes it easier for electric charges to flow, making possible more efficient solar cells and batteries. Provided/Wiesner lab
Amorphous silicon, deposited on a porous template fills the empty spaces. Laser heating melts the deposit and the top few microns of the silicon substrate. In a few nanoseconds the melted silicon recrystallizes. The substrate acts as a seed crystal for the material above, causing it to crystallize with the same alignment. This makes it easier for electric charges to flow, making possible more efficient solar cells and batteries. Provided/Wiesner lab

Abstract:
Cornell researchers have developed a new method to create a patterned single-crystal thin film of semiconductor material that could lead to more efficient photovoltaic cells and batteries.

By Bill Steele

Single-crystal films could advance solar cells

Ithaca, NY | Posted on October 8th, 2010

The "holy grail" for such applications has been to create on a silicon base, or substrate, a film with a 3-D structure at the nanoscale, with the crystal lattice of the film aligned in the same direction (epitaxially) as in the substrate. Doing so is the culmination of years of research by Uli Wiesner, professor of materials science and engineering, into using polymer chemistry to create nanoscale self-assembling structures.

He and his colleagues report the breakthrough in the Oct. 8 issue of the journal Science. They used the new method to create a film with a raised texture, made up of tiny pillars just a few nanometers across. "Just the ability to make a single-crystal nanostructure has a lot of promise," Wiesner said. "We combine that with the ability of organic polymer materials to self-assemble at the nanoscale into various structures that can be templated into the crystalline material." (A nanometer -- nm -- is a billionth of a meter, about three atoms wide.)

Wiesner's research group previously used self-assembly techniques to create Gräetzel solar cells, which use an organic dye sandwiched between two conductors. Arranging the conductors in a complex 3-D pattern creates more surface area to collect light and allows more efficient charge transport, Wiesner said.

Performance improves the most when the conducting materials are single crystals, Wiesner said. Most techniques for creating such films produce polycrystalline material -- a collection of "grains" or small crystals bunched together at random -- and grain boundaries retard the movement of electric charges, he explained.

Wiesner's method uses block co-polymers to create porous templates into which a new material can flow and crystallize. A polymer consists of organic molecules that link into long chains to form a solid. A block co-polymer is made by joining two different molecules at their ends. When they chain together and are mixed with metal oxides, one forms a nanoscale pattern of repeating geometric shapes, while the other fills the space in between. Burning the polymer away leaves a porous metal oxide nanostructure that can act as a template.

Wiesner's team created a template with hexagonal pores on a silicon single-crystal substrate and deposited films of amorphous silicon or nickel silicide over it. In collaboration with Mike Thompson, associate professor of materials science and engineering, they then heated the silicon surface with very short (nanosecond) laser pulses. This melts the newly deposited layer and the top few microns (millionths of a meter) of the silicon substrate. After only a few tens of nanoseconds the molten silicon recrystallizes with the single crystal silicon substrate acting as a seed crystal to trigger crystallization in the deposited material above it, causing that crystal to line up epitaxially with the seed.

The template is dissolved away, leaving an array of hexagonal pillars about 30 nm across. The team has made porous nanostructured films up to 100 nm thick with other complex shapes. In previous work Wiesner created lattices of cylinders, planes, spheres and complex "gyroids" by varying the composition of co-polymers.

Other materials could be deposited, the researchers said. The goal here, they said, was to demonstrate the formation of film with the same material as the substrate (officially known as homoepitaxy) and with a different material (heteroepitaxy).

In a further proof-of-concept experiment, the researchers showed that the structured thin film could be arranged in micron-scale patterns, as might be necessary in designing an electronic circuit, by laying a mask over the surface before applying laser heating.

"We have essentially gotten to the holy grail," Wiesner said. "It is not only a nanostructured single crystal, but it has an epitaxial relation to the substrate. There is no better control."

The research was supported by the National Science Foundation, Department of Homeland Security and Cornell's Energy Materials Center, funded by the U.S. Department of Energy.

####

For more information, please click here

Contacts:
Media Contact:
Joe Schwartz
(607) 254-6235

Cornell Chronicle:
Bill Steele
(607) 255-7164

Copyright © Cornell University

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

Scientists Capture Ultrafast Snapshots of Light-Driven Superconductivity: X-rays reveal how rapidly vanishing 'charge stripes' may be behind laser-induced high-temperature superconductivity April 16th, 2014

'Life Redesigned: The Emergence of Synthetic Biology' Lecture at Brookhaven Lab on Wednesday, April 30: Biomedical Engineer James Collins to Speak for BSA Distinguished Lecture Series April 16th, 2014

ECHA Planning Workshop on Regulatory Challenges in the Risk Assessment of Nanomaterials April 16th, 2014

Lumerical files a provisional patent that extends the standard eigenmode expansion propagation technique to better address waveguide component design. Lumerical’s EME propagation tool will address a wide set of waveguide applications in silicon photonics and integrated optics April 16th, 2014

Videos/Movies

Tiny particles could help verify goods: Chemical engineers hope smartphone-readable microparticles could crack down on counterfeiting April 15th, 2014

Biologists Develop Nanosensors to Visualize Movements and Distribution of Plant Stress Hormone April 15th, 2014

Director Wally Pfister joins UC Berkeley neuroengineers to discuss the science behind ‘Transcendence’ April 7th, 2014

KEEP CALM and PUBLISH PAPERS – a new video blog with graphic tutorials to scientific publishing April 7th, 2014

Thin films

Industry Veteran Fergus Clarke Joins Picodeon as CEO: Appointment comes as Picodeon prepares for growth April 8th, 2014

Scalable CVD process for making 2-D molybdenum diselenide: Rice, NTU scientists unveil CVD production for coveted 2-D semiconductor April 8th, 2014

Govt.-Legislation/Regulation/Funding/Policy

'Life Redesigned: The Emergence of Synthetic Biology' Lecture at Brookhaven Lab on Wednesday, April 30: Biomedical Engineer James Collins to Speak for BSA Distinguished Lecture Series April 16th, 2014

ECHA Planning Workshop on Regulatory Challenges in the Risk Assessment of Nanomaterials April 16th, 2014

UT Arlington physicist creates new nanoparticle for cancer therapy April 16th, 2014

Relieving electric vehicle range anxiety with improved batteries: Lithium-sulfur batteries last longer with nanomaterial-packed cathode April 16th, 2014

Possible Futures

Virus structure inspires novel understanding of onion-like carbon nanoparticles April 10th, 2014

Local girl does good March 22nd, 2014

Surface Characteristics Influence Cellular Growth on Semiconductor Material March 12th, 2014

The "Tipping Point" February 12th, 2014

Academic/Education

Director Wally Pfister joins UC Berkeley neuroengineers to discuss the science behind ‘Transcendence’ April 7th, 2014

First annual science week highlights STEM pipeline and partnerships: UB, SUNY Buffalo State and ECC team up with the City of Buffalo and its schools for April 7-11 events April 3rd, 2014

Global 450 consortium announces new general manager of internal operations: TSMC’s Cheng-Chung Chien Receives Unanimous Support, Brings History of Innovation and Efficiency to Global Consortium of Companies Driving Industry Transition to 450mm Wafer Technology March 26th, 2014

NanoTecNexus to Host "Chemistry of Wine" Fundraiser in Support of STEM Education - Collaborations Key to Success - March 20th, 2014

Self Assembly

Roomy cages built from DNA: Self-assembling cages are the largest standalone 3-D DNA structures yet, and could one day deliver drugs, or house tiny bioreactors or photonic devices March 13th, 2014

Cypress’s TrueTouch® Touchscreen Controllers Compatible with Cima NanoTech’s SANTE® Silver Nanoparticle-Based Touch Sensors: Supporting Designs for Advanced Touch Applications March 5th, 2014

Coupled carbon and peptide nanotubes achieved for the first time: twins nanotubes March 1st, 2014

A potentially revolutionnary material: Scientists produce a novel form of artificial graphene February 15th, 2014

Announcements

UT Arlington physicist creates new nanoparticle for cancer therapy April 16th, 2014

Relieving electric vehicle range anxiety with improved batteries: Lithium-sulfur batteries last longer with nanomaterial-packed cathode April 16th, 2014

Aerotech X-Y ball-screw stage for economical high performance Planar positioning April 16th, 2014

Energy Research Facility Construction Project at Brookhaven Lab Wins U.S. Energy Secretary's Achievement Award April 16th, 2014

Energy

Scientists Capture Ultrafast Snapshots of Light-Driven Superconductivity: X-rays reveal how rapidly vanishing 'charge stripes' may be behind laser-induced high-temperature superconductivity April 16th, 2014

Engineers develop new materials for hydrogen storage April 15th, 2014

A molecular approach to solar power: Switchable material could harness the power of the sun — even when it’s not shining April 15th, 2014

Scientists open door to better solar cells, superconductors and hard-drives: Research enhances understanding of materials interfaces April 14th, 2014

Battery Technology/Capacitors/Generators/Piezoelectrics/Thermoelectrics

Relieving electric vehicle range anxiety with improved batteries: Lithium-sulfur batteries last longer with nanomaterial-packed cathode April 16th, 2014

Catching the (Invisible) Wave: UC Santa Barbara researchers create a unique semiconductor that manipulates light in the invisible infrared/terahertz range, paving the way for new and enhanced applications April 11th, 2014

Nanotech Business Review 2013-2014 April 9th, 2014

Preview of Hands-on Nanotechnology Demos at ‘Chemistry of Wine’ Fundraiser to Show Nanotech Magic April 8th, 2014

Solar/Photovoltaic

A molecular approach to solar power: Switchable material could harness the power of the sun — even when it’s not shining April 15th, 2014

Shiny quantum dots brighten future of solar cells: Photovoltaic solar-panel windows could be next for your house April 14th, 2014

Scientists open door to better solar cells, superconductors and hard-drives: Research enhances understanding of materials interfaces April 14th, 2014

Better solar cells, better LED light and vast optical possibilities April 12th, 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