Thursday, December 18, 2014
YOLO COUNTY NEWS
99 CENTS

Researchers eye more efficient solar cells

By
From page A4 | January 29, 2013 |

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

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 UCD and co-author of the paper, published Jan. 25 in the journal Physical Review Letters.

“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 UCD.

“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 UCD.

“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 UCD.

— UC Davis News Service

Comments

comments

.

News

City plans signs to improve flow on Fifth Street

By Dave Ryan | From Page: A1 | Gallery

 
Former foster youths aided by UCD’s Guardian programs

By Sarah Colwell | From Page: A1 | Gallery

 
Rain Recyclers saves water for another day

By Elizabeth Case | From Page: A1 | Gallery

U.S., Cuba patch torn relations in historic accord

By The Associated Press | From Page: A2 | Gallery

 
State gets more rain, big mudslide

By The Associated Press | From Page: A2

 
Boston bombing suspect in court for first time since 2013

By The Associated Press | From Page: A2

Nominate teens for Golden Heart awards

By Enterprise staff | From Page: A3

 
Journalist will join post-film discussion Thursday

By Enterprise staff | From Page: A3

City offices will take a winter break

By Enterprise staff | From Page: A3

 
Konditorei presents free holiday concert

By Enterprise staff | From Page: A3

Supplies collected for victims of abuse

By Enterprise staff | From Page: A3

 
New technology chief will join McNaughton Newspapers

By Tanya Perez | From Page: A3 | Gallery

Feds will discuss Berryessa Snow Mountain protection

By Enterprise staff | From Page: A3

 
‘Longest Night’ service Saturday

By Enterprise staff | From Page: A3

Yolo County needs a few good advisers

By Enterprise staff | From Page: A4

 
Per Capita Davis: Time to stop fooling around

By John Mott-Smith | From Page: A4

 
NAMI-Yolo offers free mental health education program

By Enterprise staff | From Page: A5

.

Forum

Disagreement on mother’s care

By Creators Syndicate | From Page: B5

 
Remember that all lives matter

By Letters to the Editor | From Page: A6

Pollution from electric vehicles

By Letters to the Editor | From Page: A6

 
Marovich is a brilliant diplomat

By Special to The Enterprise | From Page: A6

And a jolly time was had by all

By Special to The Enterprise | From Page: A6 | Gallery

 
Tom Meyer cartoon

By Debbie Davis | From Page: A6

.

Sports

On skiing: What to know when buying new skis

By Jeffrey Weidel | From Page: B1 | Gallery

 
Devil boys host Les Curry beginning Thursday

By Enterprise staff | From Page: B1

UCD women gear up for second half of swim season

By Bruce Gallaudet | From Page: B1 | Gallery

 
Aggie men begin 4-game road trip at Air Force

By Bruce Gallaudet | From Page: B1 | Gallery

Youth roundup: DBC Juniors rider Kanz wins a cyclocross event

By Enterprise staff | From Page: B2 | Gallery

 
.

Features

College Corner: How does applying for financial aid work?

By Jennifer Borenstein | From Page: B3

 
What’s happening

By Anne Ternus-Bellamy | From Page: B3

 
Anniversary: Barbara and Jan Carter

By Special to The Enterprise | From Page: A8

Something growing in the mailbox

By Don Shor | From Page: A8 | Gallery

 
.

Arts

Sing and dance along to Cold Shot at Froggy’s

By Special to The Enterprise | From Page: A7 | Gallery

 
Point of Brew: Recollections of Christmases past

By Michael Lewis | From Page: A7

Golden Bough brings Irish holidays to The Palms

By Special to The Enterprise | From Page: A7 | Gallery

 
Come ‘Home for the Holidays’ and benefit school arts

By Special to The Enterprise | From Page: A7

.

Business

.

Obituaries

Rena Sylvia Smilkstein

By Special to The Enterprise | From Page: A4

 
.

Comics

Comics: Thursday, December 18, 2014

By Creator | From Page: B6

 
.

Last Minute Gift Guide

Young phenoms make YouTube success look like child’s play

By The Associated Press | From Page: LMG1

Classic or contemporary, it’s all holiday music to our ears

By The Associated Press | From Page: LMG2

Teen gifts: ideas for hard-to-buy-for big kids

By The Associated Press | From Page: LMG3

Gift ideas for the health-conscious

By Special to The Enterprise | From Page: LMG6

Hall of Fame proudly puts these toys on the shelf

By The Associated Press | From Page: LMG7