Light-trapping nanoshells

A team of researchers has devised a method to boost light absorption in nanoshells that can potentially make thin-film solar cells, reports a new study in Advanced Materials¹. 

When exposed to ultraviolet light, the films absorbed 20 times more light than other types of films used in similar applications.

The scientists made the films from round-shaped, hollow, zinc-oxide nanoshells that form optical cavities to trap and concentrate light like a convex lens. “The optical cavity is designed as a multi-shelled spherical structure with inner and outer walls,” explains the study’s lead author Der-Hsien Lien of the King Abdullah University of Science and Technology (KAUST), Saudi Arabia.  

This design allows light sensitivity and absorption near the surface of the nanoshells to spike. “Such structures when incorporated in solar cells, photodetectors and light-sensitive catalysts can improve their light-absorbing efficiency,” says Lien. 

The films are also sensitive to light from all directions.  

Photodetectors, made using the nanoshell films, took less than a millisecond to detect light, as shown in one of the trials reported in the study. Such a fast response and sensitivity, the researchers say, are due to the nanoshells’ structure that confines and then scatters light inside the shells.  

The team, led by Jr-Hau He in KAUST, says that this technique will open avenues for making nanodevices for light amplification, real-time imaging, and optical communication.   

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