TeraGrid News

Organic coating boosts solar cell performance

Fri, 22 Feb 2008

The energy from sunlight falling on only 9 percent of California’s Mojave Desert could power all of the United States’ electricity needs if the energy could be efficiently harvested, according to some estimates. Unfortunately, current-generation solar cell technologies are too expensive and inefficient for wide-scale commercial applications.

A team of Northwestern University researchers has developed a new anode coating strategy that significantly enhances the efficiency of solar energy power conversion. A paper about the work, which focuses on “engineering” organic material-electrode interfaces in bulk-heterojunction organic solar cells, is published online this week in the Proceedings of the National Academy of Sciences (PNAS).

This breakthrough in solar energy conversion promises to bring researchers and developers worldwide closer to the goal of producing cheaper, more manufacturable and more easily implemented solar cells. Such technology would greatly reduce our dependence on burning fossil fuels for electricity production as well as reduce the combustion product: carbon dioxide, a global warming greenhouse gas. testsetetsse

Tobin J. Marks, the Vladimir N. Ipatieff Research Professor in Chemistry in the Weinberg College of Arts and Sciences and professor of materials science and engineering, and Robert Chang, professor of materials science and engineering in the McCormick School of Engineering and Applied Science, led the research team. Other Northwestern team members were researcher Bruce Buchholz and graduate students Michael D. Irwin and Alexander W. Hains.

Of the new solar energy conversion technologies on the horizon, solar cells fabricated from plastic-like organic materials are attractive because they could be printed cheaply and quickly by a process similar to printing a newspaper (roll-to-roll processing).

To date, the most successful type of plastic photovoltaic cell is called a “bulk-heterojunction cell.” This cell utilizes a layer consisting of a mixture of a semiconducting polymer (an electron donor) and a fullerene (an electron acceptor) sandwiched between two electrodes -- one a transparent electrically conducting electrode (the anode, which is usually a tin-doped indium oxide) and a metal (the cathode), such as aluminum.
When light enters through the transparent conducting electrode and strikes the light-absorbing polymer layer, electricity flows due to formation of pairs of electrons and holes that separate and move to the cathode and anode, respectively. These moving charges are the electrical current (photocurrent) generated by the cell and are collected by the two electrodes, assuming that each type of charge can readily traverse the interface between the polymer-fullerene active layer and the correct electrode to carry away the charge -- a significant challenge.

The Northwestern researchers employed a laser deposition technique that coats the anode with a very thin (5 to 10 nanometers thick) and smooth layer of nickel oxide. This material is an excellent conductor for extracting holes from the irradiated cell but, equally important, is an efficient “blocker” which prevents misdirected electrons from straying to the “wrong” electrode (the anode), which would compromise the cell energy conversion efficiency.

In contrast to earlier approaches for anode coating, the Northwestern nickel oxide coating is cheap, electrically homogeneous and non-corrosive. In the case of model bulk-heterojunction cells, the Northwestern team has increased the cell voltage by approximately 40 percent and the power conversion efficiency from approximately 3 to 4 percent to 5.2 to 5.6 percent.

The researchers currently are working on further tuning the anode coating technique for increased hole extraction and electron blocking efficiency and moving to production-scaling experiments on flexible substrates.

tg-login.purdue.teragrid.org moved

Wed, 28 Nov 2007

The DNS alias for the main login node for the Purdue Teragrid site (tg-login.purdue.teragrid.org) has been changed to refer to a new host, which is a 64-bit RHEL3 machine like the Lear cluster behind it. If you encounter a message about the host key for tg-login.purdue.teragrid.org changing, this is no cause for alarm. Edit ~/.ssh/known_hosts, remove the old entry, and ssh to tg-login.purdue.teragrid.org again to update your known_hosts file. http://news.teragrid.org/announcements/20060920_04.php

nanoHUB a TG gateway

Wed, 28 Nov 2007

The nanoHUB led by Purdue University is an effort or the Network for Computational Nanotechnology (NCN). Led by Purdue University the nanoHUB is linking to the TeraGrid through the science gateway program. nanoHUB applications that require large compute resources are being routed to the TeraGrid using In-VIGO and Condor-G.

11 TFlops through Condor1

Wed, 28 Nov 2007

WEST LAFAYETTE, Ind. -- Rosen Center for Advanced Computing (RCAC) at Purdue University has opened up access to 11 teraflops of computing power to the TeraGrid community. Based on a new model known as "community clusters," developed by researchers at RCAC, this new computing resource will be accessible to TeraGrid researchers and educators using Condor. The community clusters currently supported by RCAC include a 1024 Xeon 64-bit (Irwindale) processor cluster, a 194 Opteron 64-bit processor cluster with InfiniBand interconnects, and a 618 Xeon 32-bit processor cluster — a combined capacity of 11 TFlops.

RCAC opens up opportunistic access to 11 TFlops for TeraGrid users

Contact:
Dr. Sebastien Goasguen, Purdue University

Community clustering is an innovative idea gaining significant momentum in the national and international cyberinfrastructure community. Under this model, researchers pool funds to contribute cluster nodes that are centrally managed by RCAC. In return, researchers get guaranteed access to the machines they purchased as well as access to any unused cluster nodes owned by other researchers. The community clusters have dedicated queues for each resource owner as well as a preemptive queue that can access any idle computational power of the cluster even nodes that researchers don't own. Backfilled by Condor, the remaining unused cycles are available to the general user community. TeraGrid jobs are routed to these clusters via a Condor job manager installed on Purdue's TeraGrid Globus gatekeeper.

"Faculty members are increasingly receiving funding through grants or startup packages to deploy their own supercomputers. These dedicated resources can be bundled together to create significant computational power. But these resources are not used all the time and a resource sharing mechanism needs to be defined to allow access to other users local or national. We have taken a first step towards true resource sharing and grid computing by deploying a condor job manager for TeraGrid users. Even though no cycles are guaranteed, we believe that significant scientific discovery and learning can be enabled through the use of the community cluster model," said Dr. Sebastien Goasguen, Senior Research Scientist and the TeraGrid Site Lead at Purdue University.

Dr. Gerhard Klimeck, the Technical Director of the NSF-funded Network for Computational Nanotechnology noted, "For my research in computational nanotechnology I need dedicated access to computing power. However, when my students or I are not using the machine I am glad to share it with anyone. The community cluster model put in place by RCAC is excellent and I have an incentive to invest in it. Giving back to the TeraGrid community through my unused cycles is a very obvious and practical thing to do."

Non-Purdue researchers can access to this new resource through the TeraGrid by requesting access via the POPS system at www.paci.org. Ideal applications for this environment are ones that require large numbers of single-processor runs. For more information, please see Purdue's TeraGrid resources page http://www.purdue.teragrid.org or send an email to: \n This e-mail address is being protected from spam bots, you need JavaScript enabled to view it .