Nanocrystalline metal electrodes for high-efficiency organic solar cells

Abstract
We demonstrate that indium ( In ) nanocrystals can be used as efficient small-work function electrodes for organic solar cells. A Schottky-barriersolar cell consisting of the In nanoelectrodes, a zinc phthalocyanine ( ZnPc ) film as a p -type organic semiconductor, and a gold counterelectrode were assembled by vacuum evaporation on an indium-tin-oxide substrate. Nanoscopic Schottky barriers, which are the origins of photovoltaic effects, were formed at the In nanocrystal ∕ ZnPc molecule interfaces in the cell. Current density under a dark condition was markedly increased by the introduction of the nanoelectrodes. The power conversion efficiency under air mass 1.5 global solar conditions was 200 fold larger than those of the conventional Pc Schottky-barriersolar cells with film electrodes.