Physicists have developed a photodetector -- a device that converts light into electrons -- by combining two distinct inorganic materials and producing quantum mechanical processes that could revolutionize the way solar energy is collected. The researchers stacked two atomic layers of tungsten diselenide on a single atomic layer of molybdenum diselenide. Such stacking results in properties vastly different from those of the parent layers, allowing for customized electronic engineering at the tiniest possible scale.