Ultra-rapid synthesis of highly porous and robust hierarchical ZnO films for dye sensitized solar cells

Dye sensitized solar cells are a promising third generation solar cell technology bearing considerable commercial potential. Here, we present the synthesis of robust, aerogel-like ZnO nanoparticle films with extremely high porosity. These film morphologies enable synthesis of stable cells with linearly increasing photocurrent up to a working-electrode thickness of 200 μm. Optimized films led to more than 100% efficiency enhancement with respect to more dense film morphologies made by wet-deposition of the same ZnO nanoparticles. These results suggest that optimization of the semiconductor-electrolyte nano-interface by a hierarchical multi-scale morphology has the potential to minimize electron-holes recombination enabling efficient thick cells with substantially higher surface area for dye absorption.