Nanoscale aluminum concaves for light-trapping in organic thin-films

• Rapid, repeatable, easily scalable nanostructuring technique on supported surfaces.
• The small supported Al nanostructures are more suitable for organic films where structural dimensions have impact.
• Al dimples ablate PMMA on specific areas experimentally, evidence of plasmonic effect.
• FDTD simulation show that field enhancement is of plasmonic nature.

Anodic aluminum oxide (AAO) templates, fabricated from oxalic acid and phosphoric acid, lead to non-periodic nanoscale concave structures in their underlying aluminum layer, which are investigated for their field-enhancement properties by applying a thin-film polymer coating based laser ablation technique. Local ablation spots, corresponding to field enhancement on the ridge edges of the aluminum concave nanostructures, are observed in surface-covering polymer films, and confirmed with FDTD studies. The field enhancement leads to improved light absorption in the applied polymer layers, which may be used as an efficient method for enhancing the power conversion efficiency of organic solar cells.