Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Atomic switcheroo explains origins of thin-film solar cell mystery

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.
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.

Abstract:
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.

Atomic switcheroo explains origins of thin-film solar cell mystery

Oak Ridge, TN | Posted on April 23rd, 2014

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/.

####

About DOE/Oak Ridge National Laboratory
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.

For more information, please click here

Contacts:
Morgan McCorkle

865-574-7308

Copyright © DOE/Oak Ridge National Laboratory

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

Metal nanoparticles induced visible-light photocatalysis: Mechanisms, applications, ways of promoting catalytic activity and outlook April 27th, 2017

Arrowhead Pharmaceuticals to Webcast Fiscal 2017 Second Quarter Results April 27th, 2017

New Product Nanoparticle preparation from Intertronics with new Thinky NP-100 Nano Pulveriser April 26th, 2017

California Research Alliance by BASF establishes more than 25 research projects in three years April 26th, 2017

Affordable STM32 Cloud-Connectable Kit from STMicroelectronics Puts More Features On-Board for Fast and Flexible IoT-Device Development April 26th, 2017

Laboratories

Video captures bubble-blowing battery in action: Researchers propose how bubbles form, could lead to smaller lithium-air batteries April 26th, 2017

NIST physicists show ion pairs perform enhanced 'spooky action' March 30th, 2017

Thin films

Nanomechanics, Inc. Unveils New Product at ICMCTF Show April 25th: Nanoindentation experts will launch the new Gemini that measures the interaction of two objects that are sliding across each other – not merely making contact April 21st, 2017

Nanomechanics Inc. President Warren Oliver, PhD to Present at ICMCTF: Nanoindentation experts will discuss new testing system that measures the interaction of two objects that are sliding across each other – not merely making contact April 17th, 2017

Bio-inspired energy storage: A new light for solar power: Graphene-based electrode prototype, inspired by fern leaves, could be the answer to solar energy storage challenge April 2nd, 2017

Govt.-Legislation/Regulation/Funding/Policy

Metal nanoparticles induced visible-light photocatalysis: Mechanisms, applications, ways of promoting catalytic activity and outlook April 27th, 2017

Graphene holds up under high pressure: Used in filtration membranes, ultrathin material could help make desalination more productive April 24th, 2017

Nanoparticle vaccine shows potential as immunotherapy to fight multiple cancer types April 24th, 2017

NanoMONITOR shares its latest developments concerning the NanoMONITOR Software and the Monitoring stations April 21st, 2017

Discoveries

Metal nanoparticles induced visible-light photocatalysis: Mechanisms, applications, ways of promoting catalytic activity and outlook April 27th, 2017

Geoffrey Beach: Drawn to explore magnetism: Materials researcher is working on the magnetic memory of the future April 25th, 2017

Using light to propel water : With new method, MIT engineers can control and separate fluids on a surface using only visible light April 25th, 2017

Nanoparticle vaccine shows potential as immunotherapy to fight multiple cancer types April 24th, 2017

Announcements

Metal nanoparticles induced visible-light photocatalysis: Mechanisms, applications, ways of promoting catalytic activity and outlook April 27th, 2017

Arrowhead Pharmaceuticals to Webcast Fiscal 2017 Second Quarter Results April 27th, 2017

New Product Nanoparticle preparation from Intertronics with new Thinky NP-100 Nano Pulveriser April 26th, 2017

California Research Alliance by BASF establishes more than 25 research projects in three years April 26th, 2017

Energy

Using light to propel water : With new method, MIT engineers can control and separate fluids on a surface using only visible light April 25th, 2017

SUNY Polytechnic Institute Announces Total of 172 Teams Selected to Compete in Solar in Your Community Challenge: Teams from 40 states, plus Washington, DC, 2 Territories, and 4 American Indian Reservations, Will Deploy Solar in Underserved Communities April 20th, 2017

Better living through pressure: Functional nanomaterials made easy April 19th, 2017

Shedding light on the absorption of light by titanium dioxide April 14th, 2017

Solar/Photovoltaic

SUNY Polytechnic Institute Announces Total of 172 Teams Selected to Compete in Solar in Your Community Challenge: Teams from 40 states, plus Washington, DC, 2 Territories, and 4 American Indian Reservations, Will Deploy Solar in Underserved Communities April 20th, 2017

Better living through pressure: Functional nanomaterials made easy April 19th, 2017

Shedding light on the absorption of light by titanium dioxide April 14th, 2017

Controlling forces between atoms, molecules, promising for ‘2-D hyperbolic’ materials April 4th, 2017

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