Light-Emitting Nanoantennas

Nanoantennas made of halide perovskites change their emisson wavelength depending on the material composition. (Source: E. Y. Tiguntseva et al.)

Nanoscale light sources and nano­antennas already found a wide range of appli­cations in several areas, such as ultra compact pixels, optical detection or tele­communi­cations. However, the fabri­cation of nano­structure-based devices is rather compli­cated since the materials typically used have a limited lumine­scence effi­ciency. What is more, single quantum dots or molecules usually emit light non-direc­tionally and weakly. An even more chal­lenging task is placing a nano­scale light source precisely near a nano­antenna.

A research group from ITMO Univer­sity in Russia managed to combine a nano­antenna and a light source in a single nano­particle. It can generate, enhance and route emission via excited resonant modes coupled with excitons. “We used hybrid perov­skite as a material for such nano­antennas,” says Ekaterina Tigunt­seva. “Unique features of perovskite enabled us to make nano­antennas from this material. We basi­cally synthesized perovskite films, and then trans­ferred material particles from the film surface to another substrate by means of pulsed laser ablation technique. Compared to alter­natives, our method is rela­tively simple and cost-effective.”

While studying the obtained perov­skite nano­particles, the scientists dis­covered that their emission can be enhanced if its spectra match with the Mie-resonant mode. “Currently, scientists are parti­cularly interested in Mie-reso­nances related to dielec­tric and semi­conductor nano­particles,” explains George Zograf, Engineer at the Laboratory of Hybrid Nano­photonics and Opto­electronics. “Perov­skites used in our work are semi­conductors with lumine­scence effi­ciency much higher than that of many other materials. Our study shows that combi­nation of excitons with Mie resonance in perov­skite nano­particles makes them effi­cient light sources at room tempera­ture.”

In addition, the radia­tion spectrum of the nano­particles can be changed by varying the anions in the material. “The structure of the material remains the same, we simply use another component in the synthesis of perov­skite films. Therefore, it is not neces­sary to adjust the method each time. It remains the same, yet the emission color of our nano­particles changes,” says Eka­terina Tigunt­seva. The scientists will continue research on light-emitting perov­skite nano­antennas using various compo­nents for their synthesis. In addition, they are deve­loping new designs of perov­skite nano­structures which may improve ultra compact optical devices. (Source: ITMO)

Reference: E. Y. Tiguntseva et al.: Light-Emitting Halide Perovskite Nanoantennas, Nano Lett181185 (2018); DOI: 10.1021/acs.nanolett.7b04727

Link: Dept. of Nanophotonics and Metamaterials, ITMO University, St. Petersburg, Russia

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