Note that (as the article explain in the middle, this is NOT a magical 200% efficiency in the energy to energy conversion, Joule to Joule, KwH to KWH, or whatever unit you want. A solar panel has a 15%-20% efficiency in the energy to energy conversion.<p>Following the ideas of the photovoltaic effect (and more generally quantum mechanics), each photon produce usually should produce only one electron. This is not a hard rule, sometimes you waste photons and get no electrons, sometimes a single photon can produce more than one electron if it is very energetic. So, they have a not magical 200% "efficiency" in the photon to electron conversion, each photon produce in average two electrons. This may be interesting in some applications, but it's not magical.<p>There are other device that have more than 100% "efficiency" in the photon to electron conversion. For example <a href="https://en.wikipedia.org/wiki/Photomultiplier_tube" rel="nofollow">https://en.wikipedia.org/wiki/Photomultiplier_tube</a> but they use high voltage, so perhaps the new invention is easier to build an maintain.<p>Note that "efficiency" or "quantum efficiency" is the correct term in that area of physics. The problem is when the press release tries to be confusing and adds Harry Potter to increase clickbaitness.