This finding is at odds with the current thinking about how supermassive black holes form at the center of new galaxies, which makes it of particular interest to astronomers.
When a current is applied across the sandwich, the electrons and holes team up at the junction of the two materials and release energy in the form of light.
"We often think of black holes pulling in matter, but actually what we observe with our current instrumentation is matter flying out, " said Timothy Kallman of NASA's Goddard Space Flight Center in Greenbelt, Maryland, in a statement.