Bringing down cost is of course the holy grail of pretty much all manufacturing, but in solar energy the issue is particularly acute.
When it first came on the scene was heralded as a major energy source of the future but that dream hasn’t come to fruition, in large part because solar cells remain expensive to make.
Researchers from North Carolina State University are the latest scientists to tackle this problem and claim they’ve found a way of creating much slimmer thin-film solar cells, without compromising the cells’ performance.
The design of the new cells, according to the scientists, features what they’ve termed a “nanoscale sandwich,” which is unlikely to be very tasty but does deliver a tasty cost reduction via an ultra-thin active layer.
Dr. Linyou Cao, an assistant professor of materials science and engineering at NC State and co-author of a paper describing the research, explained that they created a solar cell with an active layer of amorphous silicon only 70 nanometers (nm) thick.
This was a significant improvement, Cao said, since typical thin-film solar cells currently on the market that also use amorphous silicon have active layers between 300 and 500 nm thick.
Just to be clear, the active layer of the solar cell is the part that does the converting of the sun’s rays into power, either electricity or chemical fuel.
“The technique we’ve developed is very important because it can be generally applied to many other solar cell materials, such as cadmium telluride, copper indium gallium selenide, and organic materials,” Cao said in a statement.
The new technique used by the scientists is along very similar lines to the current manufacturing process. The main difference seems to be that the layer of active material, such as amorphous silicon, is sandwiched between two coatings of dielectric material.
The dielectric nanostructures are added in such a way that they create a thin film with elevated surfaces evenly spaced all along it, similar to the crenellations at the top of a medieval castle.
“The nanostructures act as very efficient optical antennas,” Cao added. “Focusing the solar energy into the active material. This focusing means we can use a thinner active layer without sacrificing performance. In the conventional thin-film design, using a thinner active layer would impair the solar cell’s efficiency.”
A great deal of research has gone into improving thin-film solar cell technology. Aside from the NC university research, one other possibility being explored is the use of nanowires.
Nanowires are one-dimensional strips of semiconductor materials only about one-thousandth the width of a human hair. One of the perceived advantages of thin-film solar cells made from nanowires is that they can be manufactured from some of the most abundant materials on Earth, rather than highly processed silicon.