Their "nanograss," a dense array of vertical nanopillars, can capture photons at a very high efficiency and could also lead to cheaper and more advanced 3D transistors, photodetectors and charge storage devices.
Solar cells are built using two different types of semiconductors ("p-type" and "n-type"), each with a slightly different composition; when the two come in close contact, they form a so-called "PN junction." This junction is a critical component of any solar cell because it generates an electric field that causes charge inside the cell to flow in a set direction, creating a voltage. Voltage times current equals (solar) power.
After decades of trial and error, scientists now believe that the ideal geometry for a PN junction would consist of a series of vertical nanoscale pillars made from one type of semiconductor (either p- or n-type) and surrounded by a semiconductor of the opposite type.