One-dimensional red phosphorous glows in unexpected ways
Aug 12, 2021
(Nanowerk News) When electrons are confined into very small spaces, they can exhibit unusual electrical, optical and magnetic behaviour. From confining electrons in two-dimensional atomic sheet graphene – a feat that won the Nobel Prize in physics in 2010 – to restricting electrons even further to achieve one-dimensionality, this broad line of research is transforming the landscape of fundamental research and technological advances in physics, chemistry, energy harvesting, information and beyond.
Red phosphorous, like graphene, belongs to a unique group of materials called one-dimensional van der Waals materials. A 1D vdW material is a radically new type of material that was discovered only in 2017. Until now, research on 1vdW materials has focused on electrical properties.
The researchers utilized the exceptional facilities of Micronova Nanofabrication Cleanroom. (Image): Aalto University / Mikko Raskinen)
The team uncovered the optical properties of 1D vdW fibrous red phosphorous through measurements like photoluminescence spectroscopy, where they shone laser light on the samples and measured the colour and brightness of the light emitted back.
The findings show the 1D vdW material demonstrates giant anisotropic linear and non-linear optical responses – in other words, the optical responses strongly depend on the orientation of the fibrous phosphorous crystal – as well as emission intensity, which relates to the number of photons emitted during a specific time.
‘The way it responded in the experiments makes 1D vdW fibrous red phosphorus a really exciting material. For example, it shows both giant anisotropic linear and non-linear responses as well as emission intensity, which is striking,’ says Dr Luojun Du, a postdoctoral researcher at Aalto University.
The material’s photoluminescence – the effect commonly seen in everyday life in reflective signs or children’s glow-in-the-dark toys, when light is emitted after absorption – also struck the researchers by surprise. The team compared the…