Featured Research

from universities, journals, and other organizations

Tiny Crystals Promise Big Benefits For Solar Technologies

Date:
January 5, 2006
Source:
Los Alamos National Laboratory
Summary:
Los Alamos National Laboratory scientists have discovered that a phenomenon called carrier multiplication, in which semiconductor nanocrystals respond to photons by producing multiple electrons, is applicable to a broader array of materials that previously thought. The discovery increases the potential for the use of nanoscrystals as solar cell materials to produce higher electrical outputs than current solar cells.

Los Alamos National Laboratory scientists have discovered that a phenomenon called carrier multiplication, in which semiconductor nanocrystals respond to photons by producing multiple electrons, is applicable to a broader array of materials that previously thought. The discovery increases the potential for the use of nanoscrystals as solar cell materials to produce higher electrical outputs than current solar cells.

Related Articles


In papers published recently in the journals Nature Physics and Applied Physics Letters, the scientists demonstrate that carrier multiplication is not unique to lead selenide nanocrystals, but also occurs with very high efficiency in nanocrystals of other compositions, such as cadmium selenide. In addition, these new results shed light on the mechanism for carrier multiplication, which likely occurs via the instantaneous photoexcitation of multiple electrons. Such a process has never been observed in macroscopic materials and it explicitly relies on the unique physics of the nanoscale size regime.

According to Richard Schaller, a Los Alamos scientist on the team, "Our research of carrier multiplication in previous years was really focused on analyzing the response of lead selenide nanocrystals to very short laser pulses. We discovered that the absorption of a single photon could produce two or even three excited electrons. We knew, somewhat instinctively, that carrier multiplication was probably not confined to lead selenide, but we needed to pursue the question."

Lead project scientist Victor Klimov explains, "Carrier multiplication actually relies upon very strong interactions between electrons squeezed within the tiny volume of a nanoscale semiconductor particle. That is why it is the particle size, not its composition that mostly determines the efficiency of the effect. In nanosize crystals, strong electron-electron interactions make a high-energy electron unstable. This electron only exists in its so-called 'virtual state' for an instant before rapidly transforming into a more stable state comprising two or more electrons."

The Los Alamos findings point toward practical photovoltaic technologies that may utilize such traditional solar cell materials as cadmium telluride, which is very similar to cadmium selenide. Other interesting opportunities may also be associated with the use of carrier multiplication in solar-fuel technologies and specifically, the production of hydrogen by photo-catalytic water splitting. The latter process requires four electrons per water molecule and its efficiency can be dramatically enhanced if these multiple electrons can be produced via a single-photon absorption event.

###

In addition to Klimov and Schaller, the Los Alamos team includes Melissa Petruska, all of the Physical Chemistry and Applied Spectroscopy group. Research on carrier multiplication at Los Alamos is funded by the DOE's Office of Basic Energy Sciences and by Los Alamo's Laboratory-Directed Research and Development (LDRD) program. More information on Los Alamos quantum dot research is available at http://quantumdot.lanl.gov online.

Los Alamos National Laboratory is operated by the University of California for the National Nuclear Security Administration (NNSA) of the U.S. Department of Energy and works in partnership with NNSA's Sandia and Lawrence Livermore national laboratories to support NNSA in its mission.

Los Alamos enhances global security by ensuring the safety and reliability of the U.S. nuclear deterrent, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to defense, energy, environment, infrastructure, health and national security concerns.



Story Source:

The above story is based on materials provided by Los Alamos National Laboratory. Note: Materials may be edited for content and length.


Cite This Page:

Los Alamos National Laboratory. "Tiny Crystals Promise Big Benefits For Solar Technologies." ScienceDaily. ScienceDaily, 5 January 2006. <www.sciencedaily.com/releases/2006/01/060105084314.htm>.
Los Alamos National Laboratory. (2006, January 5). Tiny Crystals Promise Big Benefits For Solar Technologies. ScienceDaily. Retrieved November 20, 2014 from www.sciencedaily.com/releases/2006/01/060105084314.htm
Los Alamos National Laboratory. "Tiny Crystals Promise Big Benefits For Solar Technologies." ScienceDaily. www.sciencedaily.com/releases/2006/01/060105084314.htm (accessed November 20, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Thursday, November 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Latest Minivan Crash Tests Aren't Pretty

Latest Minivan Crash Tests Aren't Pretty

Newsy (Nov. 20, 2014) Five minivans were put to the test in head-on crash simulations by the Insurance Institute for Highway Safety. Video provided by Newsy
Powered by NewsLook.com
Takata Offers "sincerest Condolences" To Victims of Malfunctioning Airbag

Takata Offers "sincerest Condolences" To Victims of Malfunctioning Airbag

Reuters - US Online Video (Nov. 20, 2014) U.S. Congress hears from a victim and company officials as it holds a hearing on the safety of Takata airbags after reports of injuries. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Shape-Shifting Architecture That Responds to Heat

Shape-Shifting Architecture That Responds to Heat

Reuters - Innovations Video Online (Nov. 19, 2014) Architectural research students in Barcelona showcase a prototype of a shape-shifting building which expands and contracts as heat is applied. Amy Pollock reports. Video provided by Reuters
Powered by NewsLook.com
Flying Aviation Expo 2014: A Weekend to Remember

Flying Aviation Expo 2014: A Weekend to Remember

Flying (Nov. 19, 2014) Get a taste of all the excitement at the first ever Flying Aviation Expo in Palm Springs, California. Video provided by Flying
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