Cheap Dye-Sensitized Solar Cell Moves toward Commercialization

05-30-2012 • http://www.technologyreview.com, By Peter Fairley

Easy-to-make solar cells that capture light with dyes have garnered an impressive string of scientific awards, including the Millennium Technology Prize in 2010. Yet they've had little commercial impact since their invention in 1988.

A novel design reported by Northwestern University researchers last week could change that, delivering a device that eliminates the dye-sensitized solar cell's inherent liability: its leak-prone and corrosive liquid electrolyte.

Unlike thin-film and silicon panels, dye-based panels can be produced in cheap roll-to-roll processes akin to printing. So even if they are less efficient than silicon solar cells, they could prove cost-effective.

The Northwestern development is just the latest in a string of advances in what Michael McGehee, director of Stanford University's Center for Advanced Molecular Photovoltaics, recently dubbed a "renaissance" in dye-sensitized cells. Recent advances in the field could finally transform these elegant scientific curiosities into practical energy-generation devices.

In a dye-sensitized solar cell, incoming light excites a porous layer of titania coated with a dye, generating negative and positive charges. The negative charges—excited electrons—flow out of the cell through the titania, while positive charges flow into a liquid electrolyte. As with electrolyte-filled alkaline batteries, leakage is an ever-present danger, especially in solar panels subject to extreme weathering. Electrolytes heated to 80° C (on a rooftop, for instance) can expand and rupture the panel's seal. The dye cells' iodine-based electrolyte is also corrosive enough to eat through even rust-resistant metals such as aluminum and stainless steel.