New research from Rice University and Tsinghua University finds that carbon nanotubes are a cheaper and more efficient alternative for platinum electrodes in dye-sensitized solar cells.

Single wall nanotubes, grown in a process invented at Rice, were shown to be much more electroactive and potentially cheaper than platinum, which is used in conventional DSC’s. Combined with a conductor (sulfide electrolytes) synthesized at Tsinghua, the result yields a more efficient and robust solar cells at a fraction of the cost of traditional silicon-based solar cells.

The two universities built working solar cells using these materials which got similar results.  They were able to achieve a power conversion efficiency of 5.25 percent. 

The record for a DSC is 11 percent power conversion efficiency achieved by a cell using iodine electrolytes and a platinum electrode.

However, platinum is expensive and the iodine absorbs light in the visible wavelength and also tends to corrode the metal based components of the DSC, which is why researchers are looking to alternative materials.

According to Rice University materials scientist Jun Lou, dye-sensitized solar cells are easier to manufacture than silicon-based cells, though not as efficient.

In a DSC, organic dyes absorb photons of sunlight and generate a charge flows between a semiconducting titanium oxide layer immersed in an electrolyte substance and the cells electrode.

The sulfide-based electrolyte developed by Tsinghua researchers replaces the iodine-based electrolytes which work well with the cheaper carbon nanotube electrodes created by Rice Lab,

The sulfide electrolyte also has the additional advantage of absorbing very little visible light, allowing more photons of light to be utilized to generate a charge and possible increase the cells output. 

"These are very versatile materials," Mr. Lou said. "Single-walled carbon nanotubes have been around at Rice for a very long time, and people have found many different ways to use them. This is another way that turns out to be very well-matched to a sulfide-based electrolyte in [dye-sensitized cell] technology."

The researchers are continuing to work with the materials to optimize their performance for better efficiency.