The sun blankets the Earth with enough photons every hour to meet the entire world’s energy needs for a year. The question is how to efficiently convert them into electricity. Even under small-scale laboratory conditions, the world’s best single-junction solar cells—the kind found in most solar panels—still max out at capturing 29 percent of the sun’s energy. That puts them just shy of the hard limit of about one third that solar researchers calculated half a century ago. But scientists studying photovoltaics—the process by which sunlight is converted into electricity—have also long suspected that this limit is not as hard as it once seemed.

The ceiling on solar cell efficiency, known as the Shockley-Queisser limit, is between 29 and 33 percent, depending on how you measure it. It assumes a single-junction cell, meaning it’s made using only one type of semiconductor and is energized by direct sunlight. To nose past the limit, researchers have tried stacking multiple types of semiconductors or using lenses to concentrate light so that the cell receives a blast hundreds of times more powerful than the sun. Earlier this year, the National Renewable Energy Lab set a world record when it used a six-junction solar cell and a beam 143 times more concentrated than sunlight to achieve a whopping 47.1 percent energy efficiency.

But this technology will never be deployed at scale. The reason, says Marc Baldo, a professor of electrical engineering and computer science at MIT, is that these ultra-high-efficiency, multilayer solar cells are far too complex and expensive to produce as solar panels. To actually get more solar energy on the electric grid requires figuring out how to hit the Shockley-Queisser limit with single-junction, silicon-based solar cells, which are comparatively easy and cheap to produce. Better yet would be finding a way to bump the limit higher. And after a decade of work, Baldo and his colleagues may have finally figured out how.

As detailed in a paper published last week in Nature, Baldo’s team coated solar cells in a thin layer of tetracene, an organic molecule that effectively splits incoming photons in two. This process is known as exciton fission and means that the solar cell is able to use high energy photons from the blue-green part of the visible spectrum.

Here’s how it works. Silicon solar cells generate an electric current by using incoming photons to knock electrons from the silicon into a circuit. How much energy does that take? It depends on an attribute of the material known as its bandgap. Silicon’s bandgap corresponds to infrared photons, which carry less energy than photons in the visible part of the electromagnetic spectrum. Photons outside silicon’s bandgap essentially go to waste. But here’s where the tetracene comes in: It splits blue-green photons into two “packets” of energy that are each equivalent to an infrared photon. So rather than each infrared photon knocking free one electron, a single photon in the blue-green spectrum can knock free two electrons. It’s essentially getting two photons for the price of one.

This new cell represents a fundamentally new approach to a well-known truism in photovoltaics research: If you want to pass the Shockley-Queisser limit, you have to capture energy from a wider range of solar photons. Because this cell doesn’t rely on an expensive stack of materials with different bandgaps to broaden its range, it might ultimately be more practical too. Baldo says that using tetracene could bump the theoretical energy efficiency limit up to 35 percent—higher than was ever thought possible for single-junction cells.