One-dimensional red phosphorus glows in unexpected ways
Strong optical properties in a 1D van der Waal material

Date:
August 12, 2021
Source:
Aalto University
Summary:
Researchers have now found that fibrous red phosphorus, when
electrons are confined in its one-dimensional sub-units, can show
large optical responses -- that is, the material shows strong
photoluminescence under light irradiation. The study shows that
strong optical properties exist in a 1D van der Waal material.



FULL STORY ==========================================================================
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.


==========================================================================
In a study published in Nature Communications, an international team
led by Aalto University researchers has now found that fibrous red
phosphorus, when electrons are confined in its one-dimensional sub-units,
can show large optical responses -- that is, the material shows strong photoluminescence under light irradiation. Red phosphorus, like graphene, belongs to a unique group of materials called one-dimensional van der
Waals (1D vdW) 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 team uncovered the optical properties of 1D vdW fibrous red phosphorus 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 phosphorus 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 photoluminescence of fibrous
red phosphorus with monolayer molybdenum disulfide (MoS2), which is
well-known for its strong photoluminescence, and found that the intensity
of the photoluminescence was more than 40 times more intense, making it ultra-bright -- albeit very briefly.

'The strong photoluminescence of fibrous red phosphorus is unexpected. In
fact, we initially expected that the photoluminescence of fibrous red phosphorus would be only weak. Based on theoretical calculations, this
effect shouldn't actually be strong so we're now doing more experiments
to clarify the origin of its after-glow,' says Du.

'I believe that one-dimensional van der Waals materials like fibrous red phosphorus show real promise for displays and other applications, which
rely on materials that demonstrate exactly the behaviours we've seen in
this study. The spectrum of its anisotropic optical response also seems to
be very wide if we compare it with responses from conventional materials,'
says Professor Zhipei Sun, who leads the group behind the study.

========================================================================== Story Source: Materials provided by Aalto_University. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Luojun Du, Yanchong Zhao, Linlu Wu, Xuerong Hu, Lide Yao, Yadong
Wang,
Xueyin Bai, Yunyun Dai, Jingsi Qiao, Md Gius Uddin, Xiaomei
Li, Jouko Lahtinen, Xuedong Bai, Guangyu Zhang, Wei Ji,
Zhipei Sun. Giant anisotropic photonics in the 1D van der Waals
semiconductor fibrous red phosphorus. Nature Communications, 2021;
12 (1) DOI: 10.1038/s41467-021- 25104-6 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210812103417.htm

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