Researchers in the Organic Photonics and Nano-optics group at the Laboratory of Organic Electronics have developed optical nanoantennas made from a conducting polymer. The antennas can be switched on and off, and will make possible a completely new type of controllable nano-optical components.
Around billions of nanodisks deposited onto area of 1 cm2. Each one of them reacts to the incident light and creates plasmons. |
[[ “Our organic antennas can be transparent to visible light while reacting to light at somewhat longer wavelengths, making them interesting for applications such as smart windows.” — Magnus Jonsson.]]
In this case, they used a variant of PEDOT, which is a widely used polymer in many other areas, including thermoelectrics and bioelectronics. “We show that light can be converted to plasmons in nanostructures of the organic material,” says Magnus Jonsson, leader of the Organic Photonics and Nano-optics group at the Laboratory of Organic Electronics.
“Our organic antennas can be transparent to visible light while reacting to light at somewhat longer wavelengths, making them interesting for applications such as smart windows,” says Magnus Jonsson.
The researchers initially carried out theoretical calculations and used simulations to design experiments, which they were subsequently able to carry out. Shangzhi Chen, doctoral student in the group, has managed to produce billions of tiny nanometer-sized disks of the organic conducting material on a surface. These small disks react to light and act as tiny antennas.
Plasmones in plastics |
Another innovation they have explored is the ability to switch the organic nanoantennas on and off, which is difficult with conventional metals. The material manufactured in the laboratory is initially in an oxidized state, and the nanoantennas are switched on.
“We have shown that when we reduce the material by exposing it to a vapor, we can switch off the conduction and in this way also the antennas. If we then reoxidise it using, for example, sulphuric acid, it regains its conductivity and the nanoantennas switch on again. This is a relatively slow process at the moment, but we have taken the first steps and shown that it is possible,” says Magnus Jonsson.
“While this is basic research, our results make possible a new type of controllable nano-optical components that we believe can be used for many applications.”
Footnote:
It is plasmons that create the beautiful glowing colors in the stained-glass windows of medieval churches and mosques. The colors of the glass arise from metal particles embedded in it. But at the time, the craftsmen didn’t know that the metals give rise to plasmons. An early example of plasmons is the Lycurgus Cup at British Museum, London.
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