Nanostructures take the color out of thin-film interference between inner interfaces

Raleigh, NC--Inspired (as are many photonics researchers) by the structure of moth eyes, researchers at North Carolina State University (NC State) have developed nanostructures that limit reflection at the interfaces where two thin films meet, suppressing the thin-film interference.¹ This can potentially improve the efficiency of thin-film solar cells and other optoelectronic devices.

Related: Tessellation of moth-eye arrays drastically cuts backscattered diffraction

Related: Antireflection coatings replicate moth-eye features

Related: Optical biomimetics emerge from a deep, dark past

The NC State nanostructures are built into a thin film that is intended to have a second thin film placed on top of it. The nanostructures are an extension of the thin film beneath them, and resemble a tightly-packed forest of thin cones. These nanostructures are “interfacial,” penetrating into whatever thin film is layered on top of them, limiting the amount of light reflected at the interface between the two films by creating an effective gradient refractive index.

Chih-Hao Chang, an assistant professor of mechanical and aerospace engineering at NC State, and his team found that the interface featuring the interfacial nanostructures reflects 100 times less light than an interface between thin films without the nanostructures.

“Our next steps are to design a solar device that takes advantage of this concept and to determine how we can scale it up for commercial applications,” Chang says.

REFERENCE:

1. Qiaoyin Yang et al., Nanotechnology, May 16, 2013; DOI: 10.1088/0957-4484/24/23/235202.