Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researching the LED Wallpaper of the Future

23.02.2018

Physicists from the University of Bremen have made a major breakthrough in understanding novel atomic thin materials that can be used, for example, to affix efficient flexible displays on curved surfaces. The results were recently published by the internationally renowned journal “Nature Communications”.

We live in a world of displays whose size and color-brilliance are constantly increasing. The further development of the light bulb is simple: It is increasingly being replaced by LEDs, in which so-called semiconductors produce the light.


Graphical representation of stacks of atomic thin crystals

Frank Jahnke

However, the uses of displays are limited because conventional semiconductor materials tend to be inflexible and rigid. Although it is possible to produce displays with organic light-emitting diodes (OLEDs), their lifetime and light output are lower than their inorganic relatives.

Now, new materials are coming on stream which are extremely thin and produce very intense light –and are at the same time surprisingly easy to manufacture: Using conventional adhesive tape it is even possible to strip individual atomic layers of special crystals in the laboratory.

Particularly suitable for this purpose are the so-called “van der Waals” crystals. A key idea here is the principle of the “Lego modular system”. The functionalities of luminous and electrically conductive, atomically thin materials are combined by stacking them directly on top of one another.

Innovative material allows use in sensors and solar cells

The materials produced in this way exhibit enormous mechanical stability. Not only do they efficiently emit light, they can also absorb light and turn it into electricity. This has already resulted in initial applications in highly sensitive sensors, and their use in flexible solar panels also seems to be a next step. This feature is particularly interesting in view of the growing demand for renewable energy.

Dancing game of particles explored

Light in a certain range of the color spectrum is generated in semiconductors by the emission of positive and negative electric charges. Owing to their different polarities, the opposite charges attract each other and can combine to form new composite particles, so-called excitons, with altered properties. In the course of their basic research on new materials, the physics team at the University of Bremen has developed a method with which these composite particles can be visualized and studied.

The scientists have been able to analyze how the occurrence of composite particles depends on the number of charges that can be controlled externally with a light emitting diode. “The unequal charges show a behavior very similar to that of dancers on a differently populated dance floor. If the density is low, there are very few dancers on the floor and it’s difficult to find a partner – so everyone dances on their own. On a well-filled dance floor, however, couples form and dance together undisturbed.

Eventually, though, an overcrowded dance floor leads to the couples colliding a lot, so that they separate and everyone dances alone again,” is how the early-career researcher Dr. Alexander Steinhoff explains his research to a layperson.

“We were able to show that the composite particles can be visualized by means of photoelectron spectroscopy.” He goes on to explain, “By so doing, a high-energy light particle is irradiated. The composite particle is crushed and its constituents are released from the semiconductor and lock onto the structure of the composite particle.”

New method brings structure into the dance

The authors suggest in the Nature article to use these findings. The relationship between free and paired charges directly affects the optical and electronic properties of the material. It can be controlled by targeted structuring of the environment to which atomic thin materials react sensitively. The scientists hereby make an important contribution to handling the “Lego-like modular system” and the production of ultra-thin opto-electronic components with tailor-made properties.

The work was funded by the German Research Foundation (DFG) in the frame of the graduate school “Quantum Mechanical Materials Modeling” at the University of Bremen. The article “Exciton fission in monolayer transition metal dichalcogenide semiconductors” can be read under this link: www.nature.com/articles/s41467-017-01298-6  (DOI number: 10.1038 / s41467-017-01298-6).

Attention editors: You will find images under:
https://seafile.zfn.unibremen.de/d/2bd6be7b3b1a4f52a4b7/

If you would like more information on this topic, feel free to contact:
Prof. Dr. Frank Jahnke
University of Bremen
Institute of Theoretical Physics
Phone: +49 421 218-62050
Email: jahnke@itp.uni-bremen.de

Stefanie Möller | idw - Informationsdienst Wissenschaft
Further information:
http://www.uni-bremen.de

More articles from Physics and Astronomy:

nachricht Levitating objects with light
19.03.2019 | California Institute of Technology

nachricht Stellar cartography
19.03.2019 | Leibniz-Institut für Astrophysik Potsdam

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Self-healing coating made of corn starch makes small scratches disappear through heat

Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.

Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...

Im Focus: Stellar cartography

The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.

A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...

Im Focus: Heading towards a tsunami of light

Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.

"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...

Im Focus: Revealing the secret of the vacuum for the first time

New research group at the University of Jena combines theory and experiment to demonstrate for the first time certain physical processes in a quantum vacuum

For most people, a vacuum is an empty space. Quantum physics, on the other hand, assumes that even in this lowest-energy state, particles and antiparticles...

Im Focus: Sussex scientists one step closer to a clock that could replace GPS and Galileo

Physicists in the EPic Lab at University of Sussex make crucial development in global race to develop a portable atomic clock

Scientists in the Emergent Photonics Lab (EPic Lab) at the University of Sussex have made a breakthrough to a crucial element of an atomic clock - devices...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Modelica Conference with 330 visitors from 21 countries at OTH Regensburg

11.03.2019 | Event News

Selection Completed: 580 Young Scientists from 88 Countries at the Lindau Nobel Laureate Meeting

01.03.2019 | Event News

LightMAT 2019 – 3rd International Conference on Light Materials – Science and Technology

28.02.2019 | Event News

 
Latest News

Molecular motors run in unison in a metal-organic framework

20.03.2019 | Life Sciences

Active substance from plant slows down aggressive eye cancer

20.03.2019 | Life Sciences

Novel sensor system improves reliability of high-temperature humidity measurements

20.03.2019 | Trade Fair News

VideoLinks
Science & Research
Overview of more VideoLinks >>>