Breakthrough in efficiency for dye-sensitized solar cells

Jun 29, 2008

In a paper published in the journal Nature Materials, EPFL professor Michael Graetzel, Shaik Zakeeruddin and colleagues from the Changchun Institute of Applied Chemistry at the Chinese Academy of Sciences have achieved a record light conversion efficiency of 8.2% in solvent-free dye-sensitized solar cells.

This breakthrough in efficiency without the use of volatile organic solvents will make it possible to pursue large scale, outdoor practical application of lightweight, inexpensive, flexible dye-sensitized solar films that are stable over long periods of light and heat exposure.

Dye-sensitized solar cell technology, invented by Michael Graetzel at EPFL in the 1990s, shows great promise as a cheap alternative to expensive silicon solar cells. Dye-sensitized cells imitate the way that plants and certain algae convert sunlight into energy. The cells are made up of a porous film of tiny (nanometer sized) white pigment particles made out of titanium dioxide. The latter are covered with a layer of dye which is in contact with an electrolyte solution. When solar radiation hits the dye it injects a negative charge in the pigment nanoparticle and a positive charge into the electrolyte resulting in the conversion of sunlight into electrical energy.

The cells are inexpensive, easy to produce and can withstand long exposure to light and heat compared with traditional silicon-based solar cells. Currently, state-of-the-art dye-sensitized cells have an overall light conversion efficiency greater than 11%, still about two times lower than silicon cell technology. A major drawback to the dye-sensitized cell technology is the electrolyte solution, which is made up of volatile organic solvents and must be carefully sealed. This, along with the fact that the solvents permeate plastics, has precluded large-scale outdoor application and integration into flexible structures.

To overcome these limitations, Graetzel and his colleagues developed a new concept -- a mixture of three solid salts as an alternative to using organic solvents as an electrolyte solution. When the three solid components are mixed together in the right proportion they turn into a melt showing excellent stability and efficiency. Graetzel is confident that further development of these types of electrolyte mixtures will lead to large-scale practical application of dye-sensitized solar cell technology, reinforcing solar energy's role as a cornerstone of alternative energy production.

Source: Ecole Polytechnique Fédérale de Lausanne

Explore further: DARPA circuit achieves speeds of 1 trillion cycles per second, earns Guinness world record

add to favorites email to friend print save as pdf

Related Stories

Recommended for you

HP announces Sprout—a truly innovative workstation

44 minutes ago

Hewlett-Packard Co has announced the development of a new kind of computer workstation—one that combines the power of a desktop computer with 3D scanning and projection—and adds a second display surface ...

Q&A: 'Interstellar' filmmaker Nolan on his robots

1 hour ago

In his secrecy-shrouded sci-fi extravaganza "Interstellar," filmmaker Christopher Nolan isn't just taking audiences to outer space. He's also sending a couple of robots along for the ride—and they're just ...

Tweet much to gain popularity is an inefficient strategy

1 hour ago

The imbalanced structure of Twitter, where some users have many followers and the large majority barely has several dozen followers, means that messages from the more influential have much more impact. Less ...

Humans are largely the problem in cyber security failures

1 hour ago

When people think about cyber and information security they often think about anti-virus software and firewalls; however, according to an information security expert from the University of Adelaide, organisations would become ...

Pirate Bay founder jailed for hacking Danish data

2 hours ago

A Danish court on Friday sentenced the Swedish founder of file-sharing site The Pirate Bay to 3½ years in prison after he was found guilty of hacking into a private company handling sensitive information for Danish authorities.

Five ways to fight online abuse with good manners

2 hours ago

Online and social media's capacity to enable anyone to communicate their ideas and views is much celebrated. So why do so many people feel nervous about getting involved with online debate?

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.