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 Appreciating the classical elegance of time crystals
20.09.2019 | ETH Zurich Department of Physics

nachricht 'Nanochains' could increase battery capacity, cut charging time
20.09.2019 | Purdue University

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: 'Nanochains' could increase battery capacity, cut charging time

How long the battery of your phone or computer lasts depends on how many lithium ions can be stored in the battery's negative electrode material. If the battery runs out of these ions, it can't generate an electrical current to run a device and ultimately fails.

Materials with a higher lithium ion storage capacity are either too heavy or the wrong shape to replace graphite, the electrode material currently used in...

Im Focus: Stevens team closes in on 'holy grail' of room temperature quantum computing chips

Photons interact on chip-based system with unprecedented efficiency

To process information, photons must interact. However, these tiny packets of light want nothing to do with each other, each passing by without altering the...

Im Focus: Happy hour for time-resolved crystallography

Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Hamburg and the European Molecular Biology Laboratory (EMBL) outstation in the city have developed a new method to watch biomolecules at work. This method dramatically simplifies starting enzymatic reactions by mixing a cocktail of small amounts of liquids with protein crystals. Determination of the protein structures at different times after mixing can be assembled into a time-lapse sequence that shows the molecular foundations of biology.

The functions of biomolecules are determined by their motions and structural changes. Yet it is a formidable challenge to understand these dynamic motions.

Im Focus: Modular OLED light strips

At the International Symposium on Automotive Lighting 2019 (ISAL) in Darmstadt from September 23 to 25, 2019, the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, a provider of research and development services in the field of organic electronics, will present OLED light strips of any length with additional functionalities for the first time at booth no. 37.

Almost everyone is familiar with light strips for interior design. LED strips are available by the metre in DIY stores around the corner and are just as often...

Im Focus: Tomorrow´s coolants of choice

Scientists assess the potential of magnetic-cooling materials

Later during this century, around 2060, a paradigm shift in global energy consumption is expected: we will spend more energy for cooling than for heating....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Optical Technologies: International Symposium „Future Optics“ in Hannover

19.09.2019 | Event News

Society 5.0: putting humans at the heart of digitalisation

10.09.2019 | Event News

Interspeech 2019 conference: Alexa and Siri in Graz

04.09.2019 | Event News

 
Latest News

Quality control in immune communication: Chaperones detect immature signaling molecules in the immune system

20.09.2019 | Life Sciences

Moderately Common Plants Show Highest Relative Losses

20.09.2019 | Life Sciences

The Fluid Fingerprint of Hurricanes

20.09.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>