Boosting the short-circuit current density of organic photovoltaics using a composite electrode

Progress in organic photovoltaic (OPV) efficiency is key to low-cost energy production. Device architectures comprising of the most effective materials, morphology, and well-designed layouts sit alongside the strategy which targets low-cost and high-performance devices. Here we report, an enhancement of the short-circuit current density, a key performance parameter, by using a silver/aluminum composite electrode in OPVs with a regular architecture. The use of the composite electrode in the inverted architecture results in a substantially reduced silver electrode thickness and thus offers material cost reductions. This work also highlights the importance of modeling the interference effects for optimizing the layer thicknesses along with systematic optimization of materials, morphology, and interfaces to further the enhancements in the field. For example, by simply reducing the thickness of the commonly used ZnO and MoO3 interlayers in an inverted OPV it is possible to improve the short-circuit density. The optical field intensity distributions and optical power confinement within the active layer are exploited to reveal the origin of this enhancement.