Planar dye-sensitized photovoltaics through cavity mode enhancement

Abstract

Dye-sensitized solar cells (DSSCs) differ from conventional solar cells in that they rely on a large area nanoparticle network to achieve sufficient absorption of sunlight. Although highly successful to date, this approach limits the opportunities to further increase DSSC power efficiency because it necessarily restricts the choice of redox shuttles to those compatible with the long electron transit times and ample recombination opportunities inherent to the nanoparticle-based architecture. Here, we use a resonantly coupled cavity scheme to demonstrate planar, thin-film DSSCs with a polarized, monochromatic incident photon to current efficiency of 17% from a single monolayer of a conventional Ru-dye. Upon illumination on resonance we observe open-circuit voltages that reach 1 V and thereby approach the theoretical limit for open-circuit voltage set by the dye and redox shuttle energy levels. The results supply new insight into processes presently limiting DSSCs and point to novel strategies to overcome these losses.