Fabrication of moth-eye patterned TiO₂ active layers for high energy efficiency and current density of dye-sensitized solar cells

Past two decades have shown the unprecedentedly rapid emergence of dye-sensitized solar cells (DSSCs) that are efficient, inexpensive, and eco-friendly. However, structural studies of the internal solar cells have not made much progress because of the high cost and complexity of the fabrication. In this study, therefore, we designed and fabricated a moth-eye patterned TiO₂ layer as a working electrode using a soft lithography method with polystyrene (PS) monolayer, and the moth-eye patterned TiO₂ active layers were constructed using a polydimethylsiloxane (PDMS) stamp via inverse honeycomb patterning having various PS beads of 400, 800, 1200 and 1600 nm. For the 1600 nm patterned stamp, Jsc is higher for moth-eye patterned TiO₂ (13.63 mA/cm²) than that for flat TiO₂ (11.09 mA/cm²), which results in a higher power efficiency of 7.66% rather than 6.40%. This result found an increment of around 23% in current density and 20% in energy conversion efficiency, mainly because of greater light-harvesting effect by its structural anti-reflective property.