In the energy sector, economic factors drive decision-making, therefore, researchers are continually looking for ways to make solar cells more durable and more efficient at converting sunlight into electricity. Silicon solar cells currently dominate the market, but have well-documented efficiency limitations. "Each photon of light can only knock loose a single electron, even if that photon carried twice the energy needed to do so" (MIT). Now, a group of researchers from MIT and Princeton University have demonstrated a method for getting high-energy photons striking silicon to kick out two electrons instead of one, opening the door for a new kind of solar cell with greater efficiency.
The innovative process is called singlet exciton fission, which is how the light's energy gets split into two separate, independently moving packets of energy. The basic concept behind this new technology has been known for decades, but actually translating the method into a full, operational silicon solar cell took years of hard work (MIT).
The tricky part was coupling that energy over into the silicon, a material that is not excitonic. In fact, this coupling had never been accomplished before. The key was in a thin intermediate layer. “A tiny strip of material at the interface between these two systems [the silicon solar cell and the tetracene layer with its excitonic properties] ended up defining everything.” In fact, this layer, acting as a bridge, finally made it possible for the single high-energy photons to trigger the release of two electrons inside the silicon cell (MIT).
The team says that commercial applications are probably still a few years off. More development needs to be done to optimize silicon cells to their maximum and to stabilize material durability, but the breakthrough was proving the coupling of the two materials to be effective (MIT). Nevertheless, this is exciting news for the solar industry as the increased efficiency will decrease overall costs and likely lead to greater adoption of solar cells.
Imaged sourced from modernize.com