Enhancement of photothermal effect using a hierarchical plasmonic structure

The photothermal effect exhibited by plasmonic structures has garnered considerable attention because of its versatile application prospects. However, the conversion efficiency of broadband light sources and large area fabrication still pose challenges. Herein, a hierarchical plasmonic structure was proposed as a photothermal substrate, which integrated a two-dimensional periodic microstructure with a disordered nanostructure. The microstructure and nanostructure were obtained through litho-etching and metal-assisted chemical etching technologies, respectively. Titanium nitride was deposited on the hierarchical structure as the mediator between the irradiation and generation of heat. The metallic nanostructure on the hierarchical structure played a crucial role in generating the thermoplasmonic effect. Moreover, the type (vertical and tapered shapes) of the microstructure and morphology (porous texture and deep trench) of the nanostructure were also altered to investigate the photothermal effect. The addition of deeper nanotrenches on the tapered microstructure exhibited a synergistic effect on the photothermal efficiency. The hierarchical plasmonic structures were experimentally demonstrated to exhibit a 3.6 times greater photothermal efficiency (change in temperature) compared to a titanium nitride film. These engineered hierarchical structures have remarkable potential for use as non-classical photothermal devices.

Automated summary

This study proposes a hierarchical plasmonic structure as a photothermal substrate, incorporating a two-dimensional periodic microstructure with a disordered nanostructure. The microstructure and nanostructure were obtained through litho-etching and metal-assisted chemical etching technologies, respectively. Titanium nitride was used as a mediator, and the metallic nanostructure played a crucial role in generating the thermoplasmonic effect. Experimental results showed that the hierarchical plasmonic structures exhibited significantly higher photothermal efficiency compared to a titanium nitride film.