Natcore Solar is claiming a potentially significant advance in thin-film solar technology in its joint research agreement with Rice University. The company said it “fabricated two families of multilayer quantum dot films, one with silicon quantum dots and the other with germanium quantum dots, both of which have demonstrated the ability to produce a photo-generated current.”
So what’s the big deal with that? Well, the company said the advance by co-founder Andrew Barron “could eliminate the need for a silicon wafer subcell,” a step forward in Natcore’s quest to perfect a process for making low cost tandem solar cells that are nearly twice as efficient as typical solar power cells.
Natcore said each film comprises “layers of silicon or germanium quantum dots embedded in a silica matrix” developed through a proprietary process Natcore has licensed, exclusively, from Rice. The company said this “liquid phase deposition” (LPD) process uniquely “decouples quantum dot formation from the silica layer growth and allows for completely independent selection of quantum dot type, size and spacing” in the silica layer. On its website, Natcore explains that LPD, “by allowing for much thinner silicon wafers, can lower silicon usage by more than 40 percent.”
“Our goal to show that multiple layers of quantum dots can be assembled using a low-cost, complete wet chemistry approach has been validated,” said Dennis Flood, Natcore’s chief technology officer. “The fact that we have demonstrated photocurrent generation in both Si (silicon) and Ge )germanium) quantum dot multilayer devices means that the entire solar cell could potentially be fabricated without the use of expensive silicon wafers for the bottom subcell of a two- or three-cell tandem device.”