July 7, 2013
Hongrui Jiang and his students at the University of Wisconsin/Madison have developed a PV (photovoltaic) cell that stores part of the energy it produces to keep the juice flowing after dark.
The top layer is a conventional silicon cell, but the cell diverts some of the electron flow to an array of zinc oxide nanowires coated with polyvinylidene fluoride polymer (PVDF). PVDF has the high dielectric constant required to store electrons.
When the sky goes dark or cloudy, stored voltage comes back through the nano wires to power the load. The prototype demonstrates only 4 percent efficiency, but Jiang expects to develop it for micro-scale devices.