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Highly efficient OLEDs produced that will make mass scale production of displays possible

Highly efficient OLEDs produced that will make mass scale production of displays possible

By BizLED Bureau

Mar 3, 2016: A team led by Professor Lee at Pohang University of Science and Technology have successfully produced highly-efficient, solution-processed fluorescence organic light-emitting diodes (OLEDs) with pure-organic thermally-activated delayed-fluorescence (TADF) emitters.

Highly efficient OLEDs produced that will make mass scale production of displays possible

This research was done to generate possibilities of mass scale production of OLED displays and solid state lighting. It was selected as a significant paper and is currently open to the public as “Layman’s abstract”. The research was published Advanced Materials.

High internal quantum efficiency (IQE) of close to 100% is shown by conventional OLEDs with phosphorescent emitters. Researchers are toying with the idea that heavy metals such as iridium and platinum into phosphorescent metal-complexes should be incorporated but they limit their commercialization. To overcome this flaw, the team uses pure-organic TADF emitters which reveal a very high IQE of close to 100% without precious metals. Further, TADF emitters have benefits of easy synthesis using pure-organic molecules and versatile molecular design, thus, reduce the synthesis cost.

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A simple, less expensive solution-process to fabricate the TADF-OLEDs is, resolving fundamental problems which are limiting the high efficiency in solution processed TADF-OLEDs. A multi-functional buffer hole injection layer (Buf-HIL) that can increase the hole injection capability to the emitting layer (EML) due to its high work function, and improves the luminescence efficiency of TADF-OLEDs by preventing exciton quenching at the HIL/EML interface was employed.

Highly efficient OLEDs produced that will make mass scale production of displays possible

Additionally, new polar aprotic solvent improved the device efficiency by improving the solubility of pure-organic TADF emitters, lessening the surface roughness and the aggregation of dopants, and managing the exciton quenching in the emitting layer.

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It is of prime importance to reduce the production cost of the devices from the perspective of industrial mass-production of OLED displays and solid-state lightings. Improvement in solution processed TADF-OLEDs will remedy the disadvantages of a complex and costly vacuum-deposition process and thus lower the production cost of the devices.

According to Professor Lee, this method uses only low-cost pure-organic molecules and simple solution process to realize the extremely high efficiency solution-processed OLEDs. The technology is a big leap toward the development of inexpensive and solution-processed OLED displays.

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