Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Photovoltaics from any semiconductor

27.07.2012
Berkeley Lab technology could open door to more widespread solar energy devices

A technology that would enable low-cost, high efficiency solar cells to be made from virtually any semiconductor material has been developed by researchers with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley.


The SFPV technology was tested for two top electrode architectures: (A) the top electrode is shaped into narrow fingers; (B) top electrode is uniformly ultrathin.

Credit: (Image courtesy of Berkeley Lab)

This technology opens the door to the use of plentiful, relatively inexpensive semiconductors, such as the promising metal oxides, sulfides and phosphides, that have been considered unsuitable for solar cells because it is so difficult to taylor their properties by chemical means.

"It's time we put bad materials to good use," says physicist Alex Zettl, who led this research along with colleague Feng Wang. "Our technology allows us to sidestep the difficulty in chemically tailoring many earth abundant, non-toxic semiconductors and instead tailor these materials simply by applying an electric field."

Zettl, who holds joint appointments with Berkeley Lab's Materials Sciences Division and UC Berkeley's Physics Department where he directs the Center of Integrated Nanomechanical Systems (COINS), is the corresponding author of a paper describing this work in the journal Nano Letters. The paper is titled "Screening-Engineered Field-Effect Solar Cells." Co-authoring it were William Regan, Steven Byrnes, Will Gannett, Onur Ergen, Oscar Vazquez-Mena and Feng Wang.

Solar cells convert sunlight into electricity using semiconductor materials that exhibit the photovoltaic effect – meaning they absorb photons and release electrons that can be channeled into an electrical current. Photovoltaics are the ultimate source of clean, green and renewable energy but today's technologies utilize relatively scarce and expensive semiconductors, such as large crystals of silicon, or thin films of cadmium telluride or copper indium gallium selenide, that are tricky or expensive to fabricate into devices.

"Solar technologies today face a cost-to-efficiency trade-off that has slowed widespread implementation," Zettl says. "Our technology reduces the cost and complexity of fabricating solar cells and thereby provides what could be an important cost-effective and environmentally friendly alternative that would accelerate the usage of solar energy."

This new technology is called "screening-engineered field-effect photovoltaics," or SFPV, because it utilizes the electric field effect, a well understood phenomenon by which the concentration of charge-carriers in a semiconductor is altered by the application of an electric field. With the SFPV technology, a carefully designed partially screening top electrode lets the gate electric field sufficiently penetrate the electrode and more uniformly modulate the semiconductor carrier concentration and type to induce a p-n junction. This enables the creation of high quality p-n junctions in semiconductors that are difficult if not impossible to dope by conventional chemical methods.

"Our technology requires only electrode and gate deposition, without the need for high-temperature chemical doping, ion implantation, or other expensive or damaging processes," says lead author William Regan. "The key to our success is the minimal screening of the gate field which is achieved through geometric structuring of the top electrode. This makes it possible for electrical contact to and carrier modulation of the semiconductor to be performed simultaneously."

Under the SFPV system, the architecture of the top electrode is structured so that at least one of the electrode's dimensions is confined. In one configuration, working with copper oxide, the Berkeley researchers shaped the electrode contact into narrow fingers; in another configuration, working with silicon, they made the top contact ultra-thin (single layer graphene) across the surface. With sufficiently narrow fingers, the gate field creates a low electrical resistance inversion layer between the fingers and a potential barrier beneath them. A uniformly thin top contact allows gate fields to penetrate and deplete/invert the underlying semiconductor. The results in both configurations are high quality p-n junctions.

Says co-author Feng Wang, "Our demonstrations show that a stable, electrically contacted p-n junction can be achieved with nearly any semiconductor and any electrode material through the application of a gate field provided that the electrode is appropriately geometrically structured."

The researchers also demonstrated the SFPV effect in a self-gating configuration, in which the gate was powered internally by the electrical activity of the cell itself.

"The self-gating configuration eliminates the need for an external gate power source, which will simplify the practical implementation of SFPV devices," Regan says. "Additionally, the gate can serve a dual role as an antireflection coating, a feature already common and necessary for high efficiency photovoltaics."

This research was supported in part by the DOE Office of Science and in part by the National Science Foundation.

Lawrence Berkeley National Laboratory (Berkeley Lab) addresses the world's most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab's scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy's Office of Science. For more, visit www.lbl.gov.

Lynn Yarris | EurekAlert!
Further information:
http://www.lbl.gov

More articles from Power and Electrical Engineering:

nachricht Six-legged robots faster than nature-inspired gait
17.02.2017 | Ecole Polytechnique Fédérale de Lausanne

nachricht Did you know that IR heat plays a central role in the production of chocolates?
14.02.2017 | Heraeus Noblelight GmbH

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Biocompatible 3-D tracking system has potential to improve robot-assisted surgery

17.02.2017 | Medical Engineering

Real-time MRI analysis powered by supercomputers

17.02.2017 | Medical Engineering

Antibiotic effective against drug-resistant bacteria in pediatric skin infections

17.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>