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.

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► Tandem organic photovoltaic cells with metal mirror microcavity are analyzed.
► Optical spacer and a capping layer in the microcavity control the optical electric fields of device.
► The short circuit current density (Jsc) of optimized microcavity device becomes higher than the normal cells.
► The Jsc of microcavity device also shows a 25% increase in Jsc compared with the ITO-based device.