Featured Research

from universities, journals, and other organizations

New Stable And High-efficiency Solar Cells Developed

Date:
January 11, 2008
Source:
Wiley-Blackwell
Summary:
Scientists have fabricated a solvent-free dye-sensitized solar cell based on a binary ionic liquid electrolyte. These devices show a light-conversion efficiency of 7.6 percent under simulated sunlight conditions, which sets a new record for a solvent-free device.

Solar cells have attracted global attention as one of the cornerstones of alternative energy. In theory, it seems to make abundant sense to tap into the energy of the sun to convert light to electricity with little or no emission of noxious pollutants. However, in practical terms, progress has been slow because of technological impediments and the many different factors that need to be optimized to obtain stable and high-efficiency devices.

Related Articles


Dye-sensitized solar cells based on dye molecules adsorbed onto titanium dioxide electrodes have emerged as one of the most attractive solar-cell constructs, combining low cost and relative ease of fabrication with high-efficiency performance. Indeed, state-of-the-art solar cells with this architecture show greater than 11% light-conversion efficiency. However, the catch is that these high-efficiency solar cells typically use volatile organic solvents as electrolytes, which essentially precludes their use in outdoor applications because of the high vapor pressure of the solvents.

Solvent-free solar cells fabricated so far show poor performance owing to the high viscosity of the alternative electrolytes. Now, a team of researchers at the Ecole Polytechnique Fédérale de Lausanne in Switzerland have fabricated a solvent-free dye-sensitized solar cell based on a binary ionic liquid electrolyte. These devices show a light-conversion efficiency of 7.6% under simulated sunlight conditions, which sets a new record for a solvent-free device.

Shaik Zakeeruddin, Michael Grätzel, and their colleagues have used a mixture of two ionic liquids as the redox electrolyte in conjunction with a novel highly conjugated ruthenium-based dye to prepare a solvent-free solar cell. Ionic liquids essentially have a vapor pressure of zero, which makes them preferable even to robust and low-volatile organic solvents. However, the typically high viscosities of ionic liquids and the fact that most of the promising ionic liquids are composed of iodide ions have precluded their application in viable cells since iodide ions tend to have a deleterious impact upon the photoconversion efficiency by quenching the dye sensitizer.

Grätzel and co-workers have tackled these challenges by adding in a low-viscosity ionic liquid comprising an inert anion. The low viscosity helps to overcome mass-transfer challenges, whereas the inert anion counteracts the deleterious influence of the iodide anions. The obtained solar cells show a record 7.6% conversion efficiency. More importantly, these cells are stable at 80 °C in the dark and under visible-light soaking at 60 °C for over a thousand hours, which points to the possibility of their use in outdoor applications in warm climates. The solvent-free nature of the electrolyte also suggests that it may be possible to construct flexible and lightweight devices based on these electrolytes.

“This is a big step in the search for nonvolatile electrolytes”, said Zakeeruddin, adding that the performance of devices based on ionic liquids had lagged so far behind that it was widely thought that these systems would be limited to indoor applications at low lighting levels. Grätzel added that the results indicate that it should be possible to further optimize the performance of these solvent-free systems.

Journal reference: Stable, High-Efficiency Ionic-Liquid-Based Mesoscopic Dye-Sensitized Solar Cells. Small. 2007, 3, 2094–2102. doi: 10.1002/smll.200700211


Story Source:

The above story is based on materials provided by Wiley-Blackwell. Note: Materials may be edited for content and length.


Cite This Page:

Wiley-Blackwell. "New Stable And High-efficiency Solar Cells Developed." ScienceDaily. ScienceDaily, 11 January 2008. <www.sciencedaily.com/releases/2008/01/080109094341.htm>.
Wiley-Blackwell. (2008, January 11). New Stable And High-efficiency Solar Cells Developed. ScienceDaily. Retrieved December 20, 2014 from www.sciencedaily.com/releases/2008/01/080109094341.htm
Wiley-Blackwell. "New Stable And High-efficiency Solar Cells Developed." ScienceDaily. www.sciencedaily.com/releases/2008/01/080109094341.htm (accessed December 20, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Saturday, December 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Lava on Track to Hit Hawaii Market

Raw: Lava on Track to Hit Hawaii Market

AP (Dec. 19, 2014) — Lava from an active volcano on Hawaii's Big Island slowed slightly but stayed on track to hit a shopping center in the small town of Pahoa. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Birds Might Be Better Meteorologists Than Us

Birds Might Be Better Meteorologists Than Us

Newsy (Dec. 19, 2014) — A new study suggests a certain type of bird was able to sense a tornado outbreak that moved through the U.S. a day before it hit. Video provided by Newsy
Powered by NewsLook.com
Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) — The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Arctic Warming Twice As Fast As Rest Of Planet

Arctic Warming Twice As Fast As Rest Of Planet

Newsy (Dec. 18, 2014) — The Arctic is warming twice as fast as the rest of the planet, thanks in part to something called feedback. Video provided by Newsy
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

 

Plants & Animals

Earth & Climate

Fossils & Ruins

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