Anodic aluminum oxide (AAO) templates on transparent conducting glass (TCO) coated glass: New prospects for a mature nano-fabrication tool

Nanoporous anodic aluminium oxide (AAO) templates, prepared by anodizing Al-coated substrates in acidic electrolytes have been an exceptionally popular tool for nano-fabrication for a long while. Even so, breakthroughs in further understanding of the anodization mechanisms as well as in fabrication know-how continue to open up new application areas for the templates. This focused review discusses recent successes in directly anodizing Al coated on transparent conducting oxides (TCOs) without instability issues and highlights the series of advancements made since. The advancements are presented from two viewpoints - (1) more in-depth analyses and understanding of the anodization mechanism including further investigations of the AAO/TCO interface and (2) integration of AAO templates (prepared on TCO-glass) and AAO-derived nanostructure arrays on TCO-coated substrates in a variety of practical applications. Our select examples of recent progress aim to demonstrate how AAO continue to be of immense interests and value to both research and the industry. We conclude the article with an outlook for direct anodization of Al on TCO-coated substrates.