Scientists from Heidelberg University and the University of St Andrews have now, for the first time, demonstrated strong light-matter coupling in semiconducting carbon nanotubes. Image: Arko Graf (Heidelberg University).As part of their research on nanomaterials for optoelectronics, scientists from Heidelberg University in Germany and the University of St Andrews in the UK have succeeded for the first time in demonstrating a strong interaction between light and matter in semiconducting carbon nanotubes.
Such strong light-matter coupling is an important step towards realizing new light sources such as electrically-pumped lasers based on organic semiconductors, which could find several important applications, including in telecommunications. These results came out of a cooperation between Jana Zaumseil at Heidelberg and Malte Gather at St Andrews, and are reported in a paper in Nature Communications.
Organic semiconductors based on carbon are an inexpensive and energy-efficient alternative to conventional inorganic semiconductors such as silicon. Light-emitting diodes (LEDs) made from these organic materials are already found in smartphone displays, while other organic semiconductor components for use in lighting technology, data transmission and photovoltaics are currently at the prototype stage.
So far, however, it has not been possible to produce one important component of optoelectronics with organic materials – the electrically-pumped laser. The main reason being that organic semiconductors have only a limited capacity for charge transport.
Research over the past few years has increasingly focused on laser-like light emission by organic semiconductors based on light-matter coupling, says Zaumseil, who is head of the Nanomaterials for Optoelectronics research group at Heidelberg University's Institute for Physical Chemistry. If photons (light) and excitons (matter) are brought together to interact, they can couple strongly enough to produce so-called exciton-polaritons, which are quasi-particles that also emit light.
Under certain conditions, such emissions can take on the properties of laser light. Combined with a sufficiently fast charge transport, exciton-polaritons could bring the production of an electrically-pumped carbon-based laser within reach.
Now, for the first time, the team led by Zaumseil and Gather has been able to demonstrate the formation of exciton-polaritons in semiconducting carbon nanotubes. Unlike other organic semiconductors, these microscopically small, tube-shaped carbon structures transport positive and negative charges extremely well. According to PhD student Arko Graf, the first author of the paper, exciton-polaritons also display extraordinary optical properties.
The scientists see their research results as an important step towards realizing electrically-pumped lasers made from organic semiconductors. “Besides the potential generation of laser light, exciton-polaritons already allow us to vary the wavelength of the light emitted by the carbon nanotubes over a wide range in the near-infrared,” says Zaumseil.
This story is adapted from material from Heidelberg University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.