Integrated tandem dye solar cells

Abstract

Tandem cells (or multi-junction cells) have been shown to be the most efficient architecture to achieve record performance for most photovoltaic technologies. In fact, tandem architectures allow devices to significantly broaden their overall absorbance spectra providing higher conversion efficiencies compared to individual cells. However, up to now, this has not been true for DSCs where record performances have been always obtained with single cells. This is mainly due to the difficulty of realizing integrated tandem DSC configurations where interlayer losses are minimized. Thus, we propose a new tandem architecture that overcomes the limitation presented so far by tandem DSCs, reporting an efficiency of 6.66% with wide room for improvement. Experimental results are corroborated with two-dimensional device simulations which allow us to understand the working mechanisms and to define optimization routes for this novel architecture. This work opens the way for further optimization of DSC technology, well beyond the actual limits, and also discloses ideas for new possible structures in the related fields of TiO₂ tandem catalysts which are important for the realization of solar fuels and electrolyte based devices.