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: UK: Former reporter sentenced for phone hacking

add to favorites email to friend print save as pdf

Related Stories

Recommended for you

UK: Former reporter sentenced for phone hacking

1 hour ago

(AP)—A former British tabloid reporter was given a 10-month suspended prison sentence Thursday for his role in the long-running phone hacking scandal that shook Rupert Murdoch's media empire.

Evaluating system security by analyzing spam volume

1 hour ago

The Center for Research on Electronic Commerce (CREC) at The University of Texas at Austin is working to protect consumer data by using a company's spam volume to evaluate its security vulnerability through the SpamRankings.net ...

Surveillance a part of everyday life

2 hours ago

Details of casual conversations and a comprehensive store of 'deleted' information were just some of what Victoria University of Wellington students found during a project to uncover what records companies ...

European Central Bank hit by data theft

3 hours ago

(AP)—The European Central Bank said Thursday that email addresses and other contact information have been stolen from a database that serves its public website, though it stressed that no internal systems or market-sensitive ...

User comments : 0