Navigation Links
Water droplets direct self-assembly process in thin-film materials

CHAMPAIGN, Ill. You can think of it as origami very high-tech origami.

Researchers at the University of Illinois have developed a technique for fabricating three-dimensional, single-crystalline silicon structures from thin films by coupling photolithography and a self-folding process driven by capillary interactions.

The films, only a few microns thick, offer mechanical bendability that is not possible with thicker pieces of the same material.

"This is a completely different approach to making three-dimensional structures," said Ralph G. Nuzzo, the G. L. Clark Professor of Chemistry at Illinois. "We are opening a new window into what can be done in self-assembly processes."

Nuzzo is corresponding author of a paper accepted for publication in the Proceedings of the National Academy of Sciences. The paper is to be posted on the journal's Early Edition Web site the week of November 23.

As a demonstration of the new capillary-driven, self-assembly process, Nuzzo and colleagues constructed spherical and cylindrical shaped silicon solar cells and evaluated their performance.

The researchers also developed a predictive model that takes into account the type of thin film to be used, the film's mechanical properties and the desired structural shape.

"The model identifies the critical conditions for self-folding of different geometric shapes," said mechanical science and engineering professor K. Jimmy Hsia. "Using the model, we can improve the folding process, select the best material to achieve certain goals, and predict how the structure will behave for a given material, thickness and shape."

To fabricate their free-standing solar cells, the researchers began by using photolithography to define the desired geometric shape on a thin film of single-crystalline silicon, which was mounted on a thicker, insulated silicon wafer. Next, they removed the exposed silicon with etchant, undercut the remaining silicon foil with acid, and released the foil from the wafer. Then they placed a tiny drop of water at the center of the foil pattern.

As the water evaporated, capillary forces pulled the edges of the foil together, causing the foil to wrap around the water droplet.

To retain the desired shape after the water had fully evaporated, the researchers placed a tiny piece of glass, coated with an adhesive, at the center of the foil pattern. The glass "froze" the three-dimensional structure in place, once it had reached the desired folded state.

"The resulting photovoltaic structures, not yet optimized for electrical performance, offer a promising approach for efficiently harvesting solar energy with thin films," said Jennifer A. Lewis, the Thurnauer Professor of Materials Science and Engineering and director of the university's Frederick Seitz Materials Research Laboratory.

Unlike conventional, flat solar cells, the curved, three-dimensional structures also serve as passive tracking optics by absorbing light from nearly all directions.

"We can look forward from this benchmark demonstration to photovoltaic structures made from thin films that behave as though they are optically dense, and much more efficient," Lewis said.

The new self-assembly process can be applied to a variety of thin-film materials, not just silicon, the researchers noted in their paper.


Contact: James E. Kloeppel
University of Illinois at Urbana-Champaign

Related biology technology :

1. Safety in Drinking Water? Monitoring for Radioactive Contaminants Only Required Every Three, Six, or Nine Years per Federal Law
2. Cellulose from Wastewater Can Now be Turned into Fuel for Cars
3. MO BIO Laboratories, Inc. Launches PowerWater(R) RNA Isolation Kit
4. EAU Completes Approval Process for Electrolyzed Water as Sanitation Process for Industrial Clean-in-Place Application
5. Reject watermelons -- the newest renewable energy source
6. Los Gatos Research Introduces Second Generation Liquid-Water Isotope Analyzer
7. Monitoring water through a snakes eyes
8. Wastewater produces electricity and desalinates water
9. Controversies on Jatropha Water-Footprint, Jatropha Cultivation for Biofuel in Tanzania and More on Jatropha Oil Shared by Jatro-Entrepreneur Ruud Van Eck.
10. Supelco(R) and MIP Technologies Launch New SPE Product for the Selective Extraction of NSAIDs From Environmental Water
11. Monitoring water through a snakes eyes
Post Your Comments:
(Date:11/25/2015)... 26, 2015 --> ... 2016 - 2020 report analyzes that automating biobanking ... quality in long-term samples, minimizing manual errors, improving ... minimizes manual errors such as mislabeling or inaccurate ... it plays a vital role in blood fractionation, ...
(Date:11/25/2015)... , Nov. 25, 2015  Neurocrine Biosciences, Inc. ... Gorman , President and CEO of Neurocrine Biosciences, will ... Conference in New York . ... visit the website approximately 5 minutes prior to the ... replay of the presentation will be available on the ...
(Date:11/25/2015)... ... 25, 2015 , ... Jessica Richman and Zachary Apte, founders ... initial angel funding process. Now, they are paying it forward to other microbiome ... investments in the microbiome space. In this, they join other successful entrepreneurs-turned-angels ...
(Date:11/24/2015)... , Nov. 24, 2015 /CNW/ - iCo Therapeutics ... today reported financial results for the quarter ended ... expressed in Canadian dollars and presented under International ... United States ," said Andrew Rae ... advancements regarding iCo-008 are not only value enriching ...
Breaking Biology Technology:
(Date:11/10/2015)... 10, 2015 About signature ... helps to identify and verify the identity of ... as the secure and accurate method of authentication ... particular individual because each individual,s signature is highly ... when dynamic signature of an individual is compared ...
(Date:11/9/2015)...  Synaptics Inc. (NASDAQ: SYNA ), the leading ... into the automotive market with a comprehensive and dedicated ... consumer electronics human interface innovation. Synaptics, industry-leading touch controllers, ... automotive industry and will be implemented in numerous locations ... , Japan , and ...
(Date:11/2/2015)...  SRI International has been awarded a contract of ... to the National Cancer Institute (NCI) PREVENT Cancer Program ... modern testing and support facilities, and analytical instrumentation to ... studies to evaluate potential cancer prevention drugs. ... Drug Development Program is an NCI-supported pipeline to bring ...
Breaking Biology News(10 mins):