Electrical shorting of organic photovoltaic films resulting from metal migration

Migration of Au nanoparticles to a depth of more than 100 nm from vacuum-deposited Au electrodes into perylene pigment (Me-PTC) films, used for organic photovoltaic cells, was clearly observed by transmission electron microscopy. The depth profile of the number of migrated Au particles was shown to coincide well with cell thickness profile of the magnitude of leakage current for the cells with a Au/Me-PTC interface. This clearly indicated that electrical shorting of very thin organic photovoltaic cells is mainly caused by the metal migration. Influence of metal migration into organic semiconductor films must be eliminated to realize high efficiency and large area solar cells. (c) 2006 American Institute of Physics.