Solar Energy in NC State Δ 11th of January 2014 Ω 11:25 AM

ΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞ
~ North Carolina State University ~ sense for Ξ ~ sense for Ξ	~ sense for Ξ ~ sense for Ξ ~ sense for Ξ	~ sense for Ξ ~ sense for Ξ ~ sense for Ξ
~ sense for Ξ ~ sense for Ξ ~ sense for Ξ	~ sense for Ξ ~ sense for Ξ ~ sense for Ξ	~ sense for Ξ ~ sense for Ξ ~ sense for Ξ
~ sense for Ξ ~ sense for Ξ ~ sense for Ξ	~ sense for Ξ ~ sense for Ξ ~ sense for Ξ	~ sense for Ξ ~ sense for Ξ ~ sense for Ξ
~ sense for Ξ ~ sense for Ξ ~ sense for Ξ	~ sense for Ξ ~ sense for Ξ ~ sense for Ξ	ξ ξ ξ
«Solar Sensing of U.S.	Θ	Θ
ΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞΞ

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

~ North Carolina State University

North Carolina State University

»North Carolina State University
Researchers from North Carolina State University have created flower-like structures out of germanium sulfide (GeS)
a semiconductor material that have extremely thin petals with an enormous surface area.
The GeS flower holds promise for next-generation energy storage devices and solar cells.
it gives a huge surface area in a small amount of space
Dr. Linyou Cao is an assistant professor of materials science and engineering at NC State and co-author of a paper on the research
could significantly increase the capacity of lithium-ion batteries, for instance,
since the thinner structure with larger surface area can hold more lithium ions
this GeS flower structure could lead to increased capacity for supercapacitors, which are also used for energy storage
to create the flower structures, researchers first heat GeS powder in a furnace until it begins to vaporize
vapor is then blown into a cooler region of the furnace, where the GeS settles out of the air into a layered sheet
that is only 20 to 30 nanometers thick, and up to 100 micrometers long
as additional layers are added, the sheets branch out from one another, creating a floral pattern similar to a marigold or carnation
to get this structure, it is very important to control the flow of the GeS vapor
so that it has time to spread out in layers, rather than aggregating into clumps
GeS is similar to materials such as graphite, which settle into neat layers or sheets
GeS is very different from graphite in that its atomic structure makes it very good at absorbing solar energy and converting it into useable power
this makes it attractive for use in solar cells, particularly since GeS is relatively inexpensive and non-toxic
many of the materials currently used in solar cells are both expensive and extremely toxic

"Role of Boundary Layer Diffusion in Vapor Deposition Growth of Chalcogenide Nanosheets: The Case of GeS,"
is published online in the journal ACS Nano.
The paper was co-authored by Cao; Dr. Chun Li, a former postdoctoral researcher at NC State,
now a professor at the University of Electronic Science and Technology of China;
Liang Huang, a former visiting Ph.D. student at NC State;
Gayatri Pongur Snigdha, a former undergraduate student at NC State; and
Yifei Yu, a Ph.D. student at NC State.
The work was supported by the U.S. Army Research Office.

Researchers Reveal How Solvent Mixtures Affect Organic Solar Cell Structure

Controlling "mixing" between acceptor and donor layers, or solar cell domains, in polymer-based solar cells
could increase their efficiency, according to a team of researchers that included physicists from North Carolina State University.
Their findings shed light on the inner workings of these solar cells, and could lead to further improvements in efficiency.

Polymer-based solar cells consist of two domains, known as the acceptor and the donor layers.
Excitons, the energy particles created by solar cells,
must be able to travel quickly to the interface of the donor and
acceptor domains in order to be harnessed as an energy source.

Researchers had believed that keeping the donor and acceptor layers as pure as possible was the best way to ensure
that the excitons could travel unimpeded, so that solar cells could capture the maximum amount of energy.

NC State physicist Harald Ade and his group worked with teams of scientists from the United Kingdom, Australia and China
to examine the physical structure and improve the production of polymer-based solar cells.

In findings published in two separate papers appearing in Advanced Energy Materials and Advanced Materials,
the researchers show that some mixing of the two domains may not be a bad thing.
In fact, if the morphology, or structure, of the mixed domains is small, the solar cell can still be quite efficient.

According to Ade, "We had previously found that the domains in these solar cells weren't pure.
So we looked at how additives affected the production of these cells.
When you manufacture the cell, the relative rate of evaporation of the solvents and additives determines
how the active layer forms and the donor and acceptor mix.

Ideally, you want the solvent to evaporate slowly enough so that the materials have time to separate
- otherwise the layers 'gum up' and lower the cell's efficiency.
We utilized an additive that slowed evaporation.
This controlled the mixing and domain size of the active layer, and the portions that mixed were small."

The efficiency of those mixed layers was excellent, leading to speculation
that perhaps some mixing of the donor and acceptor isn't a problem, as long as the domains are small.

"We're looking for the perfect mix here, both in terms of the solvents and additives we might use
in order to manufacture polymer-based solar cells, and
in terms of the physical mixing of the domains and how that may affect efficiency," Ade says.

The research was funded by the U.S. Department of Energy.
Ade is corresponding author on the Advanced Energy Materials paper,
with post docs Brian Collins, John Tumbleston and graduate student Eliot Gann contributing to the work.
Dr. Zhe Li of the University of Cambridge and Christopher McNeill of Monash University in Australia also contributed.
Ade was a contributing author on the Advanced Materials paper,
which was co-authored by Ade's post doc Wei Ma and Professor Jianhui Hou of Beijing's Chinese Academy of Sciences.

select: ~[Σ] ~[Δ]!

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

~

select: ~[Σ] ~[Ω] ~[Δ]!

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

~

select: ~[Σ] ~[Ω]!

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Small & Smart Inc reserves rights to change this document without any notice
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~