Shenzhen Enrich Electronics Co.,Ltd

For a long time, researchers have racked their brains on how to match the outstanding performance of red and green light sources with blue light sources. Because it is difficult to achieve pure blue emission at the same time without precious metal courtyard devices, researchers need to make difficult trade-offs between efficiency, color purity, cost, and lifetime.

Recently, Japanese researchers used a new molecular combination of emitters to demonstrate a new method that is expected to overcome the performance difficulties of OLED displays. By splitting the energy conversion and emission process between the two molecules, Kyushu University researchers have achieved a device that produces pure blue light emission with high efficiency, maintains a relatively long brightness time, and does not contain any expensive metal atoms.

Using this bimolecular approach, called superfluorescence, researchers have achieved a longer working life at high brightness than previously reported high-efficiency OLEDs with similar color purity.

Break through the bottleneck

Although stable blue emitters based on a process called fluorescence are often used in commercial displays, their maximum efficiency is very low. So-called phosphorescent emitters can reach the ideal quantum efficiency of 100%, but they generally exhibit a short operating life and require expensive metals such as iridium or platinum.

OPERA researchers have been developing light-emitting molecules based on the thermally activated delayed fluorescence (often referred to as TADF) process. This molecule can achieve excellent efficiency without metal atoms, but the drawback is that it has a wide emission spectrum.

OPERA researchers found in cooperation with Hatakeyama that by combining ν-DABNA with another TADF molecule developed by OPERA, as an intermediate high-speed energy converter, its lifespan is greatly increased, and narrow emission can be obtained at the same time. .

OPERA researcher Masaki Tanaka, who worked closely with Chan on the research, commented: "However, ν-DABNA is somewhat slow in transforming high-energy triploids, and these triploids are often destroyed during degradation. In order to get rid of the dangerous triploids faster Ploidy, we added an intermediate TADF molecule, which can convert triploid to haploid faster."

"Although the TADF intermediary molecule can quickly convert triploids to haploids, its emission spectrum is very broad, producing sky blue emission. Nevertheless, this intermediate can transfer many of its monomers to ν-DABNA in a high-energy state. In order to achieve fast and pure blue emission."

"Compared with most emitters, the wavelength that ν-DABNA can absorb is very close to the color it emits. This unique characteristic enables it to receive most of the energy from the wide-emission intermediate, and still emit Pure blue." Chan said.