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Chemists ID Catalytic 'Key' for Converting CO2 to Methanol

Results from experiments and computational modeling studies that definitively identify the "active site" of a catalyst commonly used for making methanol from CO2 will guide the design of improved catalysts for transforming this pollutant to useful chemicals.

Cryo-Electron Microscopy Achieves Unprecedented Resolution Using New Computational Methods

Cryo-electron microscopy (cryo-EM)--which enables the visualization of viruses, proteins, and other biological structures at the molecular level--is a critical tool used to advance biochemical knowledge. Now Berkeley Lab researchers have extended cryo-EM's impact further by developing a new computational algorithm instrumental in constructing a 3-D atomic-scale model of bacteriophage P22 for the first time.

New Study Maps Space Dust in 3-D

A new Berkeley Lab-led study provides detailed 3-D views of space dust in the Milky Way, which could help us understand the properties of this dust and how it affects views of distant objects.

Single-Angle Ptychography Allows 3D Imaging of Stressed Materials

Scientists have used a new X-ray diffraction technique called Bragg single-angle ptychography to get a clear picture of how planes of atoms shift and squeeze under stress.

New Feedback System Could Allow Greater Control Over Fusion Plasma

A physicist has created a new system that will let scientists control the energy and rotation of plasma in real time in a doughnut-shaped machine known as a tokamak.

Towards Super-Efficient, Ultra-Thin Silicon Solar Cells

Researchers from Ames Laboratory used supercomputers at NERSC to evaluate a novel approach for creating more energy-efficient ultra-thin crystalline silicon solar cells by optimizing nanophotonic light trapping.

Study IDs Link Between Sugar Signaling and Regulation of Oil Production in Plants

UPTON, NY--Even plants have to live on an energy budget. While they're known for converting solar energy into chemical energy in the form of sugars, plants have sophisticated biochemical mechanisms for regulating how they spend that energy. Making oils costs a lot. By exploring the details of this delicate energy balance, a group of scientists from the U.

High-Energy Electrons Probe Ultrafast Atomic Motion

A new technique synchronized high-energy electrons with an ultrafast laser pulse to probe how vibrational states of atoms change in time.

Rare Earth Recycling

A new energy-efficient separation of rare earth elements could provide a new domestic source of critical materials.

Two-Dimensional MXene Materials Get Their Close-Up

Researchers have long sought electrically conductive materials for economical energy-storage devices. Two-dimensional (2D) ceramics called MXenes are contenders.


Valerie Taylor Named Argonne National Laboratory's Mathematics and Computer Science Division Director

Computer scientist Valerie Taylor has been appointed as the next director of the Mathematics and Computer Science division at Argonne, effective July 3, 2017.

Three SLAC Employees Awarded Lab's Highest Honor

At a March 7 ceremony, three employees of the Department of Energy's SLAC National Accelerator Laboratory were awarded the lab's highest honor ­- the SLAC Director's Award.

Dan Sinars Represents Sandia in First Energy Leadership Class

Dan Sinars, a senior manager in Sandia National Laboratories' pulsed power center, which built and operates the Z facility, is the sole representative from a nuclear weapons lab in a new Department of Energy leadership program that recently visited Sandia.

ORNL, HTS International Corporation to Collaborate on Manufacturing Research

HTS International Corporation and the Department of Energy's Oak Ridge National Laboratory have signed an agreement to explore potential collaborations in advanced manufacturing research.

Jefferson Lab Director Honored with Energy Secretary Award

Hugh Montgomery, director of the Department of Energy's Thomas Jefferson National Accelerator Facility (Jefferson Lab), was awarded The Secretary's Distinguished Service Award by the Secretary of Energy earlier this year.

New Projects to Make Geothermal Energy More Economically Attractive

Geothermal energy, a clean, renewable source of energy produced by the heat of the earth, provides about 6 percent of California's total power. That number could be much higher if associated costs were lower. Now scientists at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) have launched two California Energy Commission-funded projects aimed at making geothermal energy more cost-effective to deploy and operate.

Southern Research Project Advances Novel CO2 Utilization Strategy

The U.S. Department of Energy's Office of Fossil Energy has awarded Southern Research nearly $800,000 for a project that targets a more cost-efficient and environmentally friendly method of producing some of the most important chemicals used in manufacturing.

Harker School Wins 2017 SLAC Regional Science Bowl Competition

After losing its first match of the day to the defending champions, The Harker School's team won 10 consecutive rounds to claim victory in the annual SLAC Regional DOE Science Bowl on Saturday, Feb. 11.

Francis Alexander Named Deputy Director of Brookhaven Lab's Computational Science Initiative

Alexander brings extensive management and leadership experience in computational science research to the position.

Kalinin, Paranthaman Elected Materials Research Society Fellows

Two researchers at Oak Ridge National Laboratory, Sergei Kalinin and Mariappan Parans Paranthaman, have been elected fellows of the Materials Research Society.


High-Energy Electrons Probe Ultrafast Atomic Motion

A new technique synchronized high-energy electrons with an ultrafast laser pulse to probe how vibrational states of atoms change in time.

Rare Earth Recycling

A new energy-efficient separation of rare earth elements could provide a new domestic source of critical materials.

Modeling the "Flicker" of Gluons in Subatomic Smashups

A new model identifies a high degree of fluctuations in the glue-like particles that bind quarks within protons as essential to explaining proton structure.

Rare Nickel Atom Has "Doubly Magic" Structure

Supercomputing calculations confirm that rare nickel-78 has unusual structure, offering insights into supernovas.

Microbial Activity in the Subsurface Contributes to Greenhouse Gas Fluxes

Natural carbon dioxide production from deep subsurface soils contributes significantly to emissions, even in a semiarid floodplain.

Stretching a Metal Into an Insulator

Straining a thin film controllably allows tuning of the materials' magnetic, electronic, and catalytic properties, essential for new energy and electronic devices.

How Moisture Affects the Way Soil Microbes Breathe

Study models soil-pore features that hold or release carbon dioxide.

ARM Data Is for the Birds

Scientists use LIDAR and radar data to study bird migration patterns, thanks to the Atmospheric Radiation Measurement (ARM) Climate Research Facility.

The Future of Coastal Flooding

Better storm surge prediction capabilities could help reduce the impacts of extreme weather events, such as hurricanes.

Estimating Global Energy Use for Water-Related Processes

Scientists find that water-related energy consumption is increasing across the globe, with pronounced differences across regions and sectors.


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Internship Program Helps Foster Development of Future Nuclear Scientists

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Atomic Switcheroo Explains Origins of Thin-Film Solar Cell Mystery

Article ID: 616918

Released: 2014-04-23 14:00:00

Source Newsroom: Oak Ridge National Laboratory

  • Credit: ORNL

    Cross-sectional electron beam-induced current maps show the difference in cadmium telluride solar cells before (pictured above) and after (below) cadmium chloride treatment. The increased brightness after treatment indicates higher current collection at the grain boundaries.

MEDIA CONTACT: Morgan McCorkle

Oak Ridge National Laboratory

Communications and Media Relations

(865) 574-7308; mccorkleml@ornl.gov

OAK RIDGE, Tenn., April 23, 2014 — Treating cadmium-telluride (CdTe) solar cell materials with cadmium-chloride improves their efficiency, but researchers have not fully understood why. Now, an atomic-scale examination of the thin-film solar cells led by the Department of Energy’s Oak Ridge National Laboratory has answered this decades-long debate about the materials’ photovoltaic efficiency increase after treatment.

A research team from ORNL, the University of Toledo and DOE’s National Renewable Energy Laboratory used electron microscopy and computational simulations to explore the physical origins of the unexplained treatment process. The results are published in Physical Review Letters (PRL).

Thin-film CdTe solar cells are considered a potential rival to silicon-based photovoltaic systems because of their theoretically low cost per power output and ease of fabrication. Their comparatively low historical efficiency in converting sunlight into energy, however, has limited the technology’s widespread use, especially for home systems.

Research in the 1980s showed that treating CdTe thin films with cadmium-chloride significantly raises the cell’s efficiency, but scientists have been unable to determine the underlying causes. ORNL’s Chen Li, first author on the PRL study, explains that the answer lay in investigating the material at an atomic level.

“We knew that chlorine was responsible for this magical effect, but we needed to find out where it went in the material’s structure,” Li said. “Only by understanding the structure can we understand what’s wrong in this solar cell -- why the efficiency is not high enough, and how can we push it further.”

By comparing the solar cells before and after chlorine treatment, the researchers realized that atom-scale grain boundaries were implicated in the enhanced performance. Grain boundaries are tiny defects that that normally act as roadblocks to efficiency, because they inhibit carrier collection which greatly reduces the solar cell power.

Using state of the art electron microscopy techniques to study the thin films’ structure and chemical composition after treatment, the researchers found that chlorine atoms replaced tellurium atoms within the grain boundaries. This atomic substitution creates local electric fields at the grain boundaries that boost the material’s photovoltaic performance instead of damaging it.

The research team’s finding, in addition to providing a long-awaited explanation, could be used to guide engineering of higher-efficiency CdTe solar cells. Controlling the grain boundary structure, says Li, is a new direction that could help raise the cell efficiencies closer to the theoretical maximum of 32 percent light-to-energy conversion. Currently, the record CdTe cell efficiency is only 20.4 percent.

“We think that if all the grain boundaries in a thin film material could be aligned in same direction, it could improve cell efficiency even further,” Li said.

The team’s research appears as “Grain-Boundary-Enhanced Carrier Collection in CdTe Solar Cells.” Coauthors are ORNL’s Chen Li, Jonathan Poplawsky, Mark Oxley and Andrew Lupini; University of Toledo’s Yelong Wu, Naba Paudel, Wanjian Yin and Yanfa Yan; University of Tennessee’s Stephen Pennycook; University of Manchester’s Sarah Haigh; University of Oxford’s Timothy Pennycook; and NREL’s Mowafak Al-Jassim. Li and Oxley hold joint appointments at Vanderbilt University.

The research was supported by the Department of Energy’s Office of Energy Efficiency and Renewable Energy through the SunShot Initiative and the Office of Basic Energy Sciences. The work was sponsored in part by the UK Engineering and Physical Sciences Research Council and through a user project supported by ORNL’s Center for Nanophase Materials Sciences (CNMS). This research used resources of the National Energy Research Scientific Computing Center. Yan acknowledges support from the Ohio Research Scholar Program.

CNMS is one of the five DOE Nanoscale Science Research Centers, NSRCs, supported by the DOE Office of Science, as premier national user facilities for interdisciplinary research at the nanoscale. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE's Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge and Sandia and Los Alamos national laboratories. For more information about the DOE NSRCs, please visit http://science.energy.gov/bes/suf/user-facilities/nanoscale-science-research-centers/.

ORNL is managed by UT-Battelle for the Department of Energy's Office of Science.

DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

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Image: http://www.ornl.gov/Image%20Library/Main%20Nav/ORNL/News/News%20Releases/2014/CdTe_highres.jpg?code=2fb8d37b-bcd7-4c01-a389-152dacfb2d5e

Caption: Cross-sectional electron beam-induced current maps show the difference in cadmium telluride solar cells before (pictured above) and after (below) cadmium chloride treatment. The increased brightness after treatment indicates higher current collection at the grain boundaries.

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