Morphology control of low temperature fabricated ZnO nanostructures for transparent active layers in all solid-state dye-sensitized solar cells

Abstract

Based on a method using sol–gel chemistry combined with diblock copolymer templating, a low-temperature route to fabricate zinc oxide (ZnO) films with tunable morphologies including foam-like, worm-like and sphere-like structures is demonstrated. The morphologies are probed using scanning electron microscopy and grazing-incidence small-angle X-ray scattering. Based on controlled nanostructured ZnO films, all solid-state dye-sensitized solar cells (ssDSSCs) are prepared, for which every layer is deposited at low temperature to reduce the energy consumption of the manufacturing process. Transparent active layers for ssDSSCs are obtained, which demonstrates the possibility for building integrated solar cells. The ssDSSCs with a worm-like ZnO morphology, exhibiting relatively better ordered interconnected three-dimensional structures and larger meso-pore sizes, show the highest power conversion efficiencies and almost 100% efficiency of charge separation and collection for the absorbed photons. After 120 days, almost 80% of the initial power conversion efficiency is maintained in ambient air conditions, which demonstrates good long-term stability of the ssDSSCs even without special encapsulation.