A primer on TiO₂ nanotubes for transparent photovoltaics

TiO₂ (titanium dioxide) has a long history in photovoltaics — famously as the mesoporous host in Grätzel cells (dye-sensitized solar cells).

Why nanotubes? Mesoporous TiO₂ is a random network. Highly ordered arrays of TiO₂ nanotubes, by contrast, offer:

• **Higher effective surface area** per unit of substrate footprint
• **Directional charge transport** along the tube axis, reducing recombination
• **Controllable optical behaviour** through geometry (tube diameter, wall thickness, length)

Manufacturing Several routes exist — anodization, template-assisted growth, hydrothermal methods. Our current focus is on electrophoretic deposition of nanostructured films, which is scalable, thickness-controllable and compatible with flexible substrates — all valuable properties for a foldable module.

Where we are Early research direction, not a validated product architecture. The point of this post is to publish what we're paying attention to, not to overclaim what we've built.