Dye-sensitized solar cells have long held the promise of cheap, easy to make solar cells, but it’s been difficult for the companies involved to actually make and sell them. But last week there was an announcement out of Northwestern University that could change that. The Northwestern University research team came up with a more efficient dye-sensitized cell that eliminates one of its biggest drawbacks – the prone to leak corrosive liquid electrolyte.
Dye-sensitized solar cells work by using the incoming light to excite a layer of titanium dioxide (also known as titania) coated with the dye. This causes positive and negative charges to be generated – the negative electrons flow out of the cell – the positive charges flow into the liquid electrolyte. But up to now, these cells were prone to leaking, especially when things got hot – the liquid electrolyte expanded and sometimes ruptured the seals. To make matters worse, the corrosive electrolyte also had a tendency to eat through aluminum and stainless steel.
The team, which consisted of chemist Mercouri Kanatzidis, materials scientist Robert Chang, and two graduate students, developed a solid iodine-based semiconductor to replace the corrosive liquid electrolyte. Previous designs using solid electrolyte designs have suffered from low efficiency, but the new design has proven to actually boost performance, since their new electrolyte also absorbs light. Kanatzidis says that the electrolyte “actually absorbs more light than the dye itself.”
They’ve developed solar cells that convert 10.2 percent of light to electricity – up to now solid-state dye sensitized cells have only hit about 7 percent. While still lower than silicon based solar cells and even thin-film solar cells, the cost of manufacturing these new dye-sensitized cells should be even lower.