October 13, 2014

Researchers from FOM Institute AMOLF, Philips Research, Ghent University (Belgium), and Mons University (Belgium), have developed a new light-emitting system whereby the emission color and directionality can be actively tuned. This system could find application in the solid-state lighting industry, where it is desired to have light-emitting devices (LEDs) that can be modified after fabrication. On September 19, 2014 the findings were published online in NanoLetters.

The new light-emitting system comprises an array of aluminum nanoantennas on top of a thin layer of quantum dots (the light emitting material), and covered by a liquid crystal. To make this system tunable, the researchers used a liquid crystal that changes with the temperature;  at room temperature the liquid crystal is ordered, while at higher temperatures the liquid crystal is disordered (see figure). By heating the liquid crystal the researchers changed the environment in which the aluminum nanoantennas are embedded. In turn, this caused the nanoantenna-enhanced light emission from the quantum dots to change in color and directionality. The process is reversible, and therefore can be applied many times back and forth to change the emission color and directionality at will.

Reference

A. Abass, S.R.K. Rodriguez, T. Ako, T. Aubert, M. Verschuuren, D. van Thourhout, J. Beeckman, Z. Hens, J. Gómez Rivas, B. Maes, Active Liquid Crystal Tuning of Metallic Nanoantenna Enhanced Light Emission from Colloidal Quantum Dots, Nano Letters, 2014, 14 (10), pp 5555–5560, DOI: 10.1021/nl501955e