Corporate Banner
Satellite Banner
Technology
Networks
Scientific Communities
 
Become a Member | Sign in
Home>News>This Article
  News
Return

Stanford Scientists Break Record for Thinnest Light-Absorber

Published: Monday, July 22, 2013
Last Updated: Monday, July 22, 2013
Bookmark and Share
Stanford scientists have built the thinnest, most efficient absorber of visible light on record, a nanosize structure that could lead to less-costly, more efficient, solar cells.

Stanford University scientists have created the thinnest, most efficient absorber of visible light on record. The nanosize structure, thousands of times thinner than an ordinary sheet of paper, could lower the cost and improve the efficiency of solar cells, according to the scientists.

Their results are published in the current online edition of the journal Nano Letters.

"Achieving complete absorption of visible light with a minimal amount of material is highly desirable for many applications, including solar energy conversion to fuel and electricity," said Stacey Bent, a professor of chemical engineering at Stanford and a member of the research team.

Bent continued, "Our results show that it is possible for an extremely thin layer of material to absorb almost 100 percent of incident light of a specific wavelength."

Thinner solar cells require less material and therefore cost less. The challenge for researchers is to reduce the thickness of the cell without compromising its ability to absorb and convert sunlight into clean energy.

For the study, the Stanford team created thin wafers dotted with trillions of round particles of gold. Each gold nanodot was about 14 nanometers tall and 17 nanometers wide.

Visible spectrum
An ideal solar cell would be able to absorb the entire visible light spectrum, from violet light waves 400 nanometers long to red waves 700 nanometers in length, as well as invisible ultraviolet and infrared light.

In the experiment, postdoctoral scholar Carl Hagglund and his colleagues were able to tune the gold nanodots to absorb one light from one spot on the spectrum: reddish-orange light waves about 600 nanometers long.

"Much like a guitar string, which has a resonance frequency that changes when you tune it, metal particles have a resonance frequency that can be fine-tuned to absorb a particular wavelength of light," said Hagglund, lead author of the study. "We tuned the optical properties of our system to maximize the light absorption."

The gold nanodot-filled wafers were fabricated at a nearby Hitachi facility using a technique called block-copolymer lithography.

Each wafer contained about 520 billion nanodots per square inch. Under the microscope, the hexagonal array of particles was reminiscent of a honeycomb.

Hagglund's team added a thin-film coating on top of the wafers using a process called atomic layer deposition. "It's a very attractive technique, because you can coat the particles uniformly and control the thickness of the film down to the atomic level, " he said.

Hagglund continued, "That allowed us to tune the system simply by changing the thickness of the coating around the dots. People have built arrays like this, but they haven't tuned them to the optimal conditions for light absorption. That's one novel aspect of our work."

Record results
The results were record-setting. "The coated wafers absorbed 99 percent of the reddish-orange light," Hagglund said. "We also achieved 93 percent absorption in the gold nanodots themselves. The volume of each dot is equivalent to a layer of gold just 1.6 nanometers thick, making it the thinnest absorber of visible light on record - about 1,000 times thinner than commercially available thin film solar cell absorbers."

The previous record-holder required an absorber layer three times thicker to reach total light absorption, he added. "So we've substantially pushed the limits of what can be achieved for light harvesting by optimizing these ultrathin, nano-engineered systems," Hagglund said.

The next step for the Stanford team is to demonstrate that the technology can be used in actual solar cells.

"We are now looking at building structures using ultrathin semiconductor materials that can absorb sunlight," said Bent, co-director of the Stanford Center on Nanostructuring for Efficient Energy Conversion (CNEEC). "These prototypes will then be tested to see how efficiently we can achieve solar energy conversion."

In the experiment, the researchers applied three types of coatings - tin sulfide, zinc oxide and aluminum oxide - on different nanodot arrays. "None of these coatings are light-absorbing," Hagglund said.

"But it has been shown theoretically that if you apply a semiconductor coating, you can shift the absorption from the metal particles to the semiconductor materials. That would create more long-lived energetic charge carriers that could be channeled into some useful process, like making an electrical current or synthesizing fuel."

Final goal
The ultimate goal, Bent added, is to develop improved solar cells and solar fuel devices by confining the absorption of sunlight to the smallest amount of material possible. "This provides a benefit in minimizing the material necessary to build the device, of course," she said.

"But the expectation is that it will also allow for higher efficiencies, because by design, the charge carriers will be produced very close to where they are desired - that is, near where they will be collected to produce an electrical current or to drive a chemical reaction."

The scientists are also considering nanodot arrays made of less expensive metals. "We chose gold because it was more chemically stable for our experiment," Hagglund said. "Although the cost of the gold was virtually negligible, silver is cheaper and better from an optical point of view if you want to make a good solar cell. Our device represents an orders-of-magnitude reduction in thickness. This suggests that we can eventually reduce the thickness of solar cells quite a lot."


Further Information
Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 2,500+ scientific posters on ePosters
  • More Than 3,800+ scientific videos on LabTube
  • 35 community eNewsletters


Sign In



Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into TechnologyNetworks.com you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

X-ray Laser Experiment Could Help in Designing Drugs for Brain Disorders
Scientists found that when two protein structures in the brain join up, they act as an amplifier for a slight increase in calcium concentration, triggering a gunshot-like release of neurotransmitters from one neuron to another.
Monday, August 24, 2015
Researchers Develop qPCR Prognosis Test for NSCLC Patients
A nine-gene molecular prognostic index (MPI) for patients with early-stage non-small cell lung cancer (NSCLC) was able to provide accurate survival stratification and could potentially inform the use of adjuvant therapy in patients struggling with the disease.
Thursday, August 20, 2015
Scientists Genetically Modify Yeast to Produce Opioids
The technique could improve access to medicines in impoverished nations, and later be used to develop treatments for other diseases.
Monday, August 17, 2015
Identifying Defective Heart Genes
A new technique could eventually enable doctors to diagnose genetic heart diseases by rapidly scanning more than 85 genes known to cause cardiac anomalies.
Thursday, August 13, 2015
Elusive Liver Stem Cell Identified in Mice by Researchers
Researchers have found a previously unknown population of cells in mice that function as liver stem cells. The finding could aid drug testing and increase understanding of liver biology and disease.
Friday, August 07, 2015
Rescuing Genetic Material from Formaldehyde Treated Tissue Samples
Formaldehyde is excellent for preserving cellular structures, but it makes it difficult to pull genetic information from tissue samples. Eric Kool and colleagues have developed a catalyst that saves RNA, which could lead to better patient outcomes.
Tuesday, August 04, 2015
Women’s Immune System Genes Operate Differently from Men’s
A new technology reveals that immune system genes switch on and off differently in women and men, and the source of that variation is not primarily in the DNA.
Friday, July 31, 2015
HIV Susceptibility Linked to Little-Understood Immune Cell Class
High levels of diversity among immune cells called natural killer cells may strongly predispose people to infection by HIV, and may be driven by prior viral exposures, according to a new study.
Thursday, July 30, 2015
Long-sought Discovery Fills in Missing Details of Cell 'Switchboard'
A biomedical breakthrough reveals never-before-seen details of the human body’s cellular switchboard that regulates sensory and hormonal responses.
Monday, July 27, 2015
DNA Damage Seen in Patients Undergoing CT Scanning
Along with the burgeoning use of advanced medical imaging tests over the past decade have come rising public health concerns about possible links between low-dose radiation and cancer.
Monday, July 27, 2015
Tiny Spheres Of Human Cells Mimic The Brain
Researchers have figured out how to create spheres of neuronal cells resembling the cerebral cortex, making functional human brain tissue available for the first time to study neuropsychiatric diseases such as autism and schizophrenia.
Wednesday, May 27, 2015
Genetic Signature Enables Early, Accurate Sepsis Diagnosis
Systemic inflammation after injuries or surgery can dramatically alter the activity of thousands of genes, but a new study shows that changes in just 11 of them are enough to detect the presence or absence of accompanying infection.
Monday, May 18, 2015
Existing Drug May Treat Deadliest Childhood Brain Tumor
For the first time, scientists have identified an existing drug that slows the growth of the deadliest childhood brain tumor.
Friday, May 08, 2015
Foreign Antibodies Mobilize Immune System to Fight Cancer
A mouse’s T cells can be primed to attack and eliminate a malignant tumor by injecting antibodies from another mouse with resistance to the tumor, as well as by activating certain signaling cells, a study has found.
Thursday, May 07, 2015
Solving The Mystery Of The Dancing Droplets
Years of research satisfy a graduate student's curiosity about the molecular minuet he observed among drops of ordinary food coloring.
Friday, March 13, 2015
Scientific News
NIH Study Finds Calorie Restriction Lowers Some Risk Factors for Age-Related Diseases
Two-year trial did not produce expected metabolic changes, but influenced other life span markers.
Immunotherapy Agent Benefits Patients with Drug-Resistant Multiple Myeloma in First Human Trial
Daratumumab proved generally safe in patients, even at the highest doses.
Low-level Arsenic Exposure Before Birth Associated with Early Puberty in Female Mice
Study examine whether low-dose arsenic exposure could have similar health outcomes in humans.
Inciting an Immune Attack On Cancer Cells
A new minimally invasive vaccine that combines cancer cells and immune-enhancing factors could be used clinically to launch a destructive attack on tumors.
‘Mutation-Tracking’ Blood Test for Breast Cancer
Scientists have developed a blood test for breast cancer able to identify which patients will suffer a relapse after treatment, months before tumours are visible on hospital scans.
Cellular Contamination Pathway for Heavy Elements Identified
Berkeley Lab scientists find that an iron-binding protein can transport actinides into cells.
Intensity of Desert Storms May Affect Ocean Phytoplankton
MIT study finds phytoplankton are extremely sensitive to changing levels of desert dust.
Common ‘Heart Attack’ Blood Test May Predict Future Hypertension
Small rises in troponin levels may have value as markers for subclinical heart damage and high blood pressure.
LaVision BioTec Reports on the Neuro Research on the Human Brain After Trauma
Company reports on the work of Dr Ali Ertürk from the Institute for Stroke and Dementia Research at LMU Munich.
NIH Study Shows No Benefit of Omega-3 Supplements for Cognitive Decline
Research was published in the Journal of the American Medical Association.
Scroll Up
Scroll Down
Skyscraper Banner

Skyscraper Banner
Go to LabTube
Go to eposters
 
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
2,500+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
3,800+ scientific videos
Close
Premium CrownJOIN TECHNOLOGY NETWORKS PREMIUM FREE!