Carbon nanotubes turn electrical current into light-matter quasi-particles

July 18, 2017
Schematic illustration of the new field-effect transistor device developed by researchers at Heidelberg and St Andrews. The transistor converts electrical current into light-matter quasi-particles and is based on single walled carbon nano-tubes that are embedded between two metallic mirrors forming an optical micro-cavity. Credit: Yuriy Zakharko (Heidelberg University)

Material scientists and physicists from Heidelberg University (Germany) and the University of St Andrews (Scotland) have demonstrated electrical generation of hybrid light-matter particles, so-called exciton-polaritons, by using field-effect transistors with semiconducting carbon nanotubes integrated in optical micro-cavities.

The extraordinary stability of these transistors enabled electrical pumping at unprecedented rates, which paves the way for electrically pumped lasers with solution-processed and carbon-based semiconductors. As the emission of these light sources can be tuned across a wide range of the near-infrared spectrum, this work holds particular promise for applications in telecommunications.

These results, published in Nature Materials, are the latest outcome of a fruitful cooperation between Professor Dr Jana Zaumseil (Heidelberg) and Professor Dr Malte C. Gather (St Andrews).

Research on optoelectronic devices using carbon-based and organic has led to a variety of novel applications, such as for energy efficient, bright and high-resolution smartphones displays and TVs.

However, despite the rapid development in this area, electrically pumped lasing from organic materials remains elusive. One major challenge is to generate the high pumping rates required for lasing. Recently, so called lasers have received a lot of attention as they provide a new and potentially more efficient way to generate laser-like light.

Instead of relying purely on photons as in a conventional laser, the polariton laser uses photons that are strongly coupled to the excited states of the material. This coupled nature of the polaritons can facilitate the generation of laser-like light if high enough current densities could be achieved.

Previously the same team showed that it is possible to form polaritons in semiconducting carbon nanotubes at room temperature by external optical excitation. In their latest work, the researchers now found a way to generate polaritons electrically.

To achieve this, they developed a carbon nanotube-based light-emitting field-effect transistor that was embedded between two metal mirrors in close proximity acting as an optical micro-cavity. In such a device the current flow is perpendicular to the optical feedback, which allows both to be optimized independently.

Because of the extreme stability and high conductivity provided by the carbon nanotubes in this device, current densities orders of magnitude above any previously reported values were achieved. Calculations by PhD student Arko Graf, one of the first authors of the study, show that with further improvements to the device architecture, electrically pumped polariton lasing will be within realistic reach.

Professor Zaumseil explains: "Besides the potential generation of laser light, these devices can also be used to reversibly tune between strong and weak light-matter coupling, which opens a route to more fundamental investigations."

Professor Gather added: "Our curiosity to understand what happens when we combine tailored nanomaterials with high-quality photonic structures is really what drives this collaboration."

The paper "Electrical pumping and tuning of exciton-polaritons in microcavities" by A. Graf, M. Held, Y. Zakharko, L. Tropf, M.C. Gather and J. Zaumseil is published online in the 17 July 2017 issue of Nature Materials.

Explore further: Carbon nanotubes couple light and matter

More information: Arko Graf et al, Electrical pumping and tuning of exciton-polaritons in carbon nanotube microcavities, Nature Materials (2017). DOI: 10.1038/nmat4940

Related Stories

Carbon nanotubes couple light and matter

November 15, 2016

With their research on nanomaterials for optoelectronics, scientists from Heidelberg University and the University of St Andrews (Scotland) have succeeded for the first time to demonstrate a strong interaction of light and ...

Engineering researchers achieve organic laser breakthrough

June 21, 2010

(PhysOrg.com) -- Researchers at the University of Michigan have achieved a long sought-after optics phenomenon that could lead to more efficient and flexible lasers for telecommunications and quantum computing applications, ...

Jellyfish proteins used to create polariton laser

August 22, 2016

(Phys.org)—A combined team of researchers from Scotland and Germany has developed a way to create a polariton laser by using jellyfish proteins cultivated in E. coli cells. In their paper published in the journal Science ...

Recommended for you

Engineers create plants that glow

December 13, 2017

Imagine that instead of switching on a lamp when it gets dark, you could read by the light of a glowing plant on your desk.

Faster, more accurate cancer detection using nanoparticles

December 12, 2017

Using light-emitting nanoparticles, Rutgers University-New Brunswick scientists have invented a highly effective method to detect tiny tumors and track their spread, potentially leading to earlier cancer detection and more ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.