LIPSS-Sticks: Laser induced double self organization enhances the broadband light harvesting of TiO2 nanotube arrays

TL;DR

This paper introduces LIPSS-Sticks, a laser-induced surface structuring method that enhances broadband light harvesting in TiO2 nanotube arrays by combining laser patterning with electrochemical growth, resulting in improved light collection.

Contribution

It demonstrates a novel double self-organization process combining laser-induced surface structures with electrochemical anodization for nanostructure fabrication.

Findings

LIPSS-Sticks increase light collection efficiency by 2x in the 400-1400 nm range.

The templated growth process differs from standard anodization, enabling hierarchical nanostructures.

Method is applicable to various metals and alloys for advanced nanostructured surfaces.

Abstract

Sub-wavelength laser induced periodic surface structures (LIPSS-Sticks) created by ultrashort pulsed laser irradiation on the surface of titanium are used for the first time to template the electrochemical growth of titanium dioxide nanotube arrays. This is an example of a double self-organized process, as both LIPSS formation and electrochemical anodization involve spontaneous generation of order from initially non-ordered precursors. LIPSS-Sticks have a 2x greater visible to near infrared light (400 - 1400 nm) collection efficiency compared to flat titanium dioxide due to the enhanced light scattering from grating-like structures. The growth of nanostructures with time was modelled electrostatically to explain the features of a templated anodization process that differ from the usual anodization of flat surfaces. This new templated growth method is general and can also be applied to Cu, W, Fe, Ti alloys and Al for the fabrication of hierarchically nanostructured surfaces using two complementary fabrication techniques: ultrashort pulsed laser ablation and electrochemical anodization.