Ultra-thin high-efficiency organic solar cells from Princeton

Fresh out of a first round of experiments at Princeton’s NanoStructure Laboratory, Dr. Steven Chou and Dr. Wei Ding released this report on the progress of their “plasmonic cavity with subwavelength hole-array” solar cell (PlaCSH). Using 30 nanometer-thick gold mesh instead of the indium-tin-oxide (ITO) layer that photovoltaic solar cells usually make use of, the Princeton team has managed to make PlaCSH solar cells 175% more efficient than traditional PV technology.

The gold nano-mesh is more efficient in several ways, thinking about the life cycle of solar cells. Indeed, gold is a rare metal (one that’s ever-increasing in value) but actually ends up being more cost effective than continuing to use the indium-tin-oxide compound we’ve been using thus far. Gold itself may not be cheap, but we’re talking about nano scale technology here — a nanometer, measuring in at one billionth of a meter, is usually used to scale dimensions at the atomic level. We use micrometers (a mere millionth of a meter) to measure human hair, just to give you an idea of how thin these gold nano-mesh layers are — the gold nano-mesh just doesn’t require that much material, especially considering the efficiency of Dr. Chou’s invented nanofabrication method. Price is a real measure of real resources, so getting the cost of manufacturing these solar cells down makes sense from an environmental sustainability perspective too, not just economic practicality.

Most importantly, however, the PlaCSH solar cells lose far less energy to reflection than traditional PV cells. Once light energy passes through the nano-mesh, it’s incredibly difficult for it to escape. The points in the nano-mesh through which light would usually be reflected back out are actually smaller than the photons themselves, so these otherwise rogue photons stick around to lend us their energy after all. The PlaCSH cells are significantly more efficient under cloud-cover, too, for those concerned with intermittency.

This innovative technology has the potential to revolutionize the solar energy industry and loosen the grip of fossil fuel dependency. Once the upfront costs of solar cells become competitive with the overall costs of fossil fuel production, it will make more economic sense to invest in solar technology over natural gas, e.g., because the pay-back period will be much shorter. The solar energy route offers reasonable (and decreasing) upfront costs and little to no maintenance costs — and, most obviously, we have more solar energy than we know what to do with. We may have to mine the gold to produce the nano-mesh, so it’s not totally benign, but it’s far less invasive than, say, Mountaintop Removal Mining.

Here to another step toward our sustainable energy future!



PS – This article by Grant Brunner of ExtremeTech has some nice diagrams depicting the way PlaCSH solar cells work in comparison to traditional ITO PV.