Enhancement of the short circuit current in organic photovoltaic devices with microcavity structures

We demonstrate that the use of a microcavity structure can overcome the trade-off between exciton diffusion and optical absorption in planar heterojunction organic photovoltaic cells. Optical simulation based on the copper phthalocyanine (CuPc)-fullerene donor-acceptor system showed that the microcavity device with the spacer layer confines a large electric field inside the cavity so that high external quantum efficiency can be achieved even with a 10-nm-thick CuPc layer, which is comparable to the exciton diffusion length of the layer. The optimized microcavity device leads to an enhancement of the short circuit current of up to 51.6% compared with the conventional device.