News | March 18, 2020

Material With Fog Effect Creates Pleasant Laser Light

International research team headed by the CAU develops extremely porous material made of "white graphene" for new laser light applications

With a porosity of 99.99%, it consists practically only of air and is therefore one of the lightest substances in the world: aerobornitride is the name of the material that an international research team headed by the Christian-Albrechts-Universität zu Kiel (CAU) developed. The scientists assume that they have created a central basis for using laser light as a lighting element. Based on a boron-nitrogen compound, they developed a three-dimensional nanostructure that scatters light very strongly and hardly absorbs it. Irradiated with a laser, the material emits uniform lighting, which, depending on the type of laser, is much more efficient and powerful than LED light. With laser light, lamps for car headlights, In future, projectors or room lighting will become smaller and brighter. The research team published their results in the current issue of the renowned specialist magazineNature Communications , which was released today (March 18). The project is part of the Europe-wide research initiative "Graphene Flagship", in which a total of around 150 research groups from science and industry in 23 countries are involved.

Details that are only a millionth of a millimeter in size: this is the focus of the research focus »Nanosciences and Surface Research« (Kiel Nano, Surface and Interface Science - KiNSIS) at the Christian-Albrechts-University in Kiel (CAU). There are different laws, namely quantum physics, in the nanocosmos than in the macroscopic world. Through intensive interdisciplinary collaboration between physics, chemistry, engineering and life sciences, the focus is on understanding the systems in this dimension and implementing the findings in an application-related manner. Molecular machines, novel sensors, bionic materials, quantum computers, advanced therapies and much more can result from

More light in the smallest space
In research and industry, laser light has long been seen as the "next generation" of light sources that could exceed the efficiency of light-emitting diodes (LEDs). “For very bright or a lot of light, you need a large number of LEDs and thus space. The same amount of light could also be obtained with a laser structure that is a thousandth smaller, ”emphasizes Dr.-Ing. Fabian Schütt the potential. The materials scientist from the "Functional Nanomaterials" working group at the CAU is the first author of the study, in which further researchers from Germany, England, Italy, Denmark and South Korea are involved.

Powerful small light sources allow numerous applications. The first test applications such as in car headlights are already available, but laser lamps have not yet been able to gain widespread coverage. On the one hand, this is due to the intense, directed light of the laser beam. Secondly, laser light is monochromatic, so it consists of only one wavelength. This leads to an uncomfortable flickering when a laser beam is reflected from a surface.

Porous structure scatters the light extremely strongly
"Previous developments in laser light normally work with phosphors. However, they generate a relatively cold light, are not long-term stable and are not very efficient, ”says Professor Rainer Adelung, head of the working group. The Kiel research team therefore takes a different approach: They developed a strongly scattering nanostructure made of boron nitride, which is also referred to as "white graphene" and absorbs extremely little light. This structure consists of a filigree network of innumerable fine hollow tubes of a few micrometers. If a laser beam hits it, it is extremely scattered inside the structure and a homogeneous light is emitted. "Our material looks like an artificial fog that creates a uniform, pleasant light," explains Schütt.

The nanostructure not only ensures that the material withstands the intense laser light, but can also scatter different wavelengths. Red, green and blue laser light can be mixed to create targeted color effects in addition to normal white - for example for use in innovative room lighting. Extremely lightweight laser diodes could lead to completely new design concepts in the future. "However, in order to be able to compete with LEDs in the future, the efficiency of laser diodes must also be improved," said Schütt. The research team is now looking for industrial partners to take the step from laboratory to application.

Wide range of applications for aeromaterials
In the meantime, the Kiel researchers can use their method of developing highly porous nanostructures for different starting materials, in addition to boron nitride, graphene or graphite. In this way, more and more new, lightweight materials, so-called "aeromaterials" are created, which allow particularly innovative applications. The scientists are currently researching the development of self-cleaning air filters for aircraft in collaboration with companies and other universities.

About The “Graphene Flagship”:
With a total budget of one billion euros, the Graphene flagship is the largest research initiative in the European Union. Around 150 research groups from science and industry in 23 countries are involved in the application of graphene from the laboratory. Due to its special combination of properties such as good conductivity and high stability combined with flexibility, the material is seen as a material of the future for numerous applications in the field of energy or electronics.

Source: Christian-Albrechts-Universit├Ąt zu Kiel (CAU)