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Single-Layer OLED Pave Future of Printable Displays

A new OLED concept has been developed. Scientists at the MPI-P led by group leader Dr. Gert-Jan Wetzelaer have developed this new OLED concept.

Now, researchers have developed an OLED which consists only of one single layer that is supplied with electricity via two electrodes. This is said to simplify the production of such OLEDs and paving the way for printable displays.

 OLED concept

Compared to conventional light-emitting diodes, however, the luminosity and lifetime of OLEDs are currently lower, which is why they represent a current field of research.

In their first prototype, the Mainz scientists were able to show that they can generate a brightness of the emitted light of 10,000 candela/square meter with a voltage of only 2.9 volts – this corresponds to about 100 times the luminosity of modern screens. Achieving such high luminosity at this low voltage is a record for current OLEDs. The researchers were also able to measure an external efficiency of 19%, which means that 19% of the electrical energy supplied is converted into light that comes out in the direction of the viewer. Also with this value, the OLED prototype can compete with current OLEDs consisting of five or even more layers.

In continuous operation, the researchers were able to measure a so-called LT50 lifetime of almost 2000 hours at a brightness equivalent to ten times that of modern displays. Within this time, the initial luminosity has dropped to 50% of its value.

“For the future, we hope to be able to improve the concept even further and thus achieve even longer lifetimes. This means that the concept could be used for industrial purposes,” explained Wetzelaer. The scientists hope that their newly developed single-layer concept – i.e. the reduced complexity of OLEDs – will contribute to the identification and improvement of the processes responsible for the reduction in a lifetime.

The scientists are using a light-emitting layer based on so-called “Thermally Activated Delayed Fluorescence” (TADF). This physical principle has been known for several decades, but became the focus of OLED research about 10 years ago, when an efficient conversion of electrical energy into the light was demonstrated in Japan.

Since then, researchers have been working to produce TADF-based OLEDs, as these do not require expensive molecular complexes containing rare-earth metals that are being used in current OLEDs.

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Niloy Banerjee

A generic movie-buff, passionate and professional with print journalism, serving editorial verticals on Technical and B2B segments, crude rover and writer on business happenings, spare time playing physical and digital forms of games; a love with philosophy is perennial as trying to archive pebbles from the ocean of literature. Lastly, a connoisseur in making and eating palatable cuisines.

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