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South Korean researchers develop ‘low-cost’ OLEDs

South Korean researchers develop ‘low-cost’ OLEDs

By BizLED Bureau

Mar 16, 2016: A cost-effective method of producing highly efficient organic light-emitting diode (OLED) displays, commonly used in HD TVs, has been found by a team of South Korean researchers.

The team developed a cheaper, solution-processed, highly efficient fluorescence organic light-emitting diodes (OLEDs) using pure-organic thermally-activated delayed-fluorescence (TADF) emitters. Advanced Materials published the report of the findings.

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Conventional OLEDs use phosphorescent emitters which show high internal quantum efficiency (IQE) of as high as 100 percent. Due to the use of heavy precious metals, the commercial buying and selling face a limitation. To overcome these challenges, the research team used pure-organic TADF emitters, which are not precious and show a very high IQE of nearly 100 percent.

Additionally, TADF emitters are easy to synthesize using pure-organic molecules and versatile molecular design. This helps greatly in reducing the costs. Led by Professor Lee Tae-Woo from the department of materials science and engineering at Pohang University of Science and Technology, the team introduced an inexpensive, simple solution-process to fabricate the TADF-OLEDs by solving fundamental problems, thus limiting the high efficiency in solution-processed TADF-OLEDs.

READ ALSO: Pure-organic emitters enable mass-scale production of OLEDs

The team used a multi-functional buffer hole injection layer to increase the hole injection capability to the emitting layer due to its high work function. They further improved the luminescence efficiency of TADF-OLEDs by preventing exciton quenching at the interface between the hole injection layer and the emitting layer. A new polar solvent was used to improve the device efficiency by upgrading the solubility of pure-organic TADF emitters, reducing the surface roughness and the aggregation of dopants, and managing the exciton quenching in the emitting layer.

This development in solution processed TADF-OLEDs tackles the challenges of a complex and expensive vacuum-deposition process to lower production cost of the devices. It is essential to lower the production cost of the devices for industrial mass production.

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