Microcavity tandem solar cells with a short circuit current higher than single cells

We demonstrate by numerical simulation that microcavity tandem organic photovoltaic cells (OPVs) with a capping layer can have a higher short circuit current (Jsc) than normal ITO based tandem OPVs without the microcavity structure and corresponding single cells. A microcavity tandem OPV consists of SubPc–C60 and PbPc–C60 donor–acceptor pairs of each subcell. Two reflecting electrodes, spacer layers, and a capping layer in the microcavity structure control the optical electric field of the device so that Jsc in the tandem OPV becomes higher than the normal cells even in its thinner active layers. The optimized microcavity device leads to a 25% increase in Jsc compared with the conventional ITO-based device employing the same donor–acceptor pair, and a 5% increase in Jsc compared with conventional ITO-based single cells.