Inexpensive Solar Cell Coating May Lead To Big Increases In Solar Cell Efficiency, 1 Photon Knocks Loose 2 Electrons | CleanTechnica

Inexpensive Solar Cell Coating May Lead To Big Increases In Solar Cell Efficiency, 1 Photon Knocks Loose 2 Electrons | CleanTechnica

For the past couple of decades, the Shockley-Queisser efficiency limit of 34% has been considered the maximum that a single optimized semiconductor junction could hope to achieve. But according to the press release from MIT, this limit could soon be shown to be irrelevant.
The principle behind the new technique has been understood since the 1960s, but had until now not successfully been put into practice, according to Marc Baldo, a professor of electrical engineering at MIT. The research team “was able, for the first time, to perform a successful ‘proof of principle’ of the idea, which is known as singlet exciton fission,” the press release stated.
Typically, in a photovoltaic (PV) cell, one photon only knocks loose one electron, and that loose electron is then harnessed to provide the electrical current. Whatever energy remains of the photon after knocking loose the electron is then lost as waste heat. But now, with the new technique, the extra energy is used to knock loose two electrons instead of just one, which also reduces waste heat. This makes for a much more efficient system.