Featured Research

from universities, journals, and other organizations

One in, two out: Simulating more efficient solar cells

Date:
January 28, 2013
Source:
University of California Davis (UCD)
Summary:
Using an exotic form of silicon could substantially improve the efficiency of solar cells, according to computer simulations.

Computer simulations show that when a light particle (blue wave on left) hits a crystal of a high-pressure form of silicon, it releases two electron-hole pairs (red circles/green rings), which generate electric current.
Credit: Stefan Wippermann/UC Davis photo

Using an exotic form of silicon could substantially improve the efficiency of solar cells, according to computer simulations by researchers at the University of California, Davis, and in Hungary.

The work was published Jan. 25 in the journal Physical Review Letters.

Solar cells are based on the photoelectric effect: a photon, or particle of light, hits a silicon crystal and generates a negatively charged electron and a positively charged hole. Collecting those electron-hole pairs generates electric current.

Conventional solar cells generate one electron-hole pair per incoming photon, and have a theoretical maximum efficiency of 33 percent. One exciting new route to improved efficiency is to generate more than one electron-hole pair per photon, said Giulia Galli, professor of chemistry at UC Davis and co-author of the paper.

"This approach is capable of increasing the maximum efficiency to 42 percent, beyond any solar cell available today, which would be a pretty big deal," said lead author Stefan Wippermann, a postdoctoral researcher at UC Davis.

"In fact, there is reason to believe that if parabolic mirrors are used to focus the sunlight on such a new-paradigm solar cell, its efficiency could reach as high as 70 percent," Wippermann said.

Galli said that nanoparticles have a size of nanometers, typically just a few atoms across. Because of their small size, many of their properties are different from bulk materials. In particular, the probability of generating more than one electron-hole pair is much enhanced, driven by an effect called "quantum confinement." Experiments to explore this paradigm are being pursued by researchers at the Los Alamos National Laboratory, the National Renewable Energy Laboratory in Golden, Colo., as well as at UC Davis.

"But with nanoparticles of conventional silicon, the paradigm works only in ultraviolet light," Wippermann said. "This new approach will become useful only when it is demonstrated to work in visible sunlight."

The researchers simulated the behavior of a structure of silicon called silicon BC8, which is formed under high pressure but is stable at normal pressures, much as diamond is a form of carbon formed under high pressure but stable at normal pressures.

The computer simulations were run through the National Energy Research Scientific Supercomputing Center at the Lawrence Berkeley Laboratory, which granted the project 10 million hours of supercomputer time.

The simulations demonstrated that nanoparticles of silicon BC8 indeed generate multiple electron-hole pairs per photon even when exposed to visible light.

"This is more than an academic exercise. A Harvard-MIT paper showed that when normal silicon solar cells are irradiated with laser light, the energy the laser emits may create a local pressure high enough to form BC8 nanocrystals. Thus, laser or chemical pressure treatment of existing solar cells may turn them into these higher-efficiency cells," said co-author Gergely Zimanyi, professor of physics at UC Davis.

Other authors of the paper are Marton Voros and Adam Gali at the Budapest University of Technology and Economics, Hungary.

The work was funded by a National Science Foundation Solar Collaborative grant awarded to Zimanyi, Galli and colleagues at UC Davis and UC Santa Cruz in 2011. The project brings together experts in material science, chemistry, computer simulations and statistics to develop new approaches to solar power.


Story Source:

The above story is based on materials provided by University of California Davis (UCD). Note: Materials may be edited for content and length.


Cite This Page:

University of California Davis (UCD). "One in, two out: Simulating more efficient solar cells." ScienceDaily. ScienceDaily, 28 January 2013. <www.sciencedaily.com/releases/2013/01/130128142900.htm>.
University of California Davis (UCD). (2013, January 28). One in, two out: Simulating more efficient solar cells. ScienceDaily. Retrieved October 23, 2014 from www.sciencedaily.com/releases/2013/01/130128142900.htm
University of California Davis (UCD). "One in, two out: Simulating more efficient solar cells." ScienceDaily. www.sciencedaily.com/releases/2013/01/130128142900.htm (accessed October 23, 2014).

Share This



More Computers & Math News

Thursday, October 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Chameleon Camouflage to Give Tanks Cloaking Capabilities

Chameleon Camouflage to Give Tanks Cloaking Capabilities

Reuters - Innovations Video Online (Oct. 22, 2014) — Inspired by the way a chameleon changes its colour to disguise itself; scientists in Poland want to replace traditional camouflage paint with thousands of electrochromic plates that will continuously change colour to blend with its surroundings. The first PL-01 concept tank prototype will be tested within a few years, with scientists predicting that a similar technology could even be woven into the fabric of a soldiers' clothing making them virtually invisible to the naked eye. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Internet of Things Aims to Smarten Your Life

Internet of Things Aims to Smarten Your Life

AP (Oct. 22, 2014) — As more and more Bluetooth-enabled devices are reaching consumers, developers are busy connecting them together as part of the Internet of Things. (Oct. 22) Video provided by AP
Powered by NewsLook.com
Free Math App Is A Teacher's Worst Nightmare

Free Math App Is A Teacher's Worst Nightmare

Newsy (Oct. 22, 2014) — New photo-recognition software from MicroBlink, called PhotoMath, solves linear equations and simple math problems with step-by-step results. Video provided by Newsy
Powered by NewsLook.com
Rate Hike Worries Down on Inflation Data

Rate Hike Worries Down on Inflation Data

Reuters - Business Video Online (Oct. 22, 2014) — Inflation remains well under control according to the latest consumer price index, giving the Federal Reserve more room to keep interest rates low for awhile. Bobbi Rebell reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins