Schematic of organic photovoltaic device showing the processes to generate electricity: (1) Incoming photons generate electrons in a polymer; (2) Electrons move to bottom electrodes through nanoscale acceptor; (3) Holes transport to top electrode via polymer; (4) Electrons collected at bottom electrode and (5) Holes collected at the top electrode. Credit: Seth Darling, Center for Nanoscale Materials, Argonne National Laboratory