Efficiency increase in OLED emitters

OLED emitter First Commercial Blue OLED Emitter Expected This Year?

2024-08-01 From Hendrik Härter | Translated by AI 3 min Reading Time

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Red and green OLED emitters have reached near 100 percent efficiency. However, blue emitters face more complex challenges. Here’s an overview of the current state of the art.

The color blue: There are three emitter materials available for OLED displays. The efficiency of the blue emitters is currently 25 percent.(Image: freely licensed / Pixabay) — The color blue: There are three emitter materials available for OLED displays. The efficiency of the blue emitters is currently 25 percent.
(Image: freely licensed / Pixabay)

The most advanced red and green OLED emitters boast nearly 100 percent internal quantum efficiency (IQE), leaving little room for further improvement in emitter efficiency itself. However, enhancing light extraction remains crucial. Blue OLED emitters, on the other hand, currently achieve only about 25 percent efficiency, with three-quarters of the energy going to waste. Elevating blue emitter efficiency to 100 percent IQE could boost overall display efficiency by 20 to 30 percent.

For an OLED emitter, there are five points that reflect important performance features: high quantum yield, accurate color reproduction, long lifespan, desired color purity and brightness, cost-effective and scalable production.

Develop better blue emitters

Achieving these criteria, especially for blue emitters, is a complex challenge. Not just the emitter layer, but the entire OLED material stack needs to be optimized. This includes the carrier materials, electron transport layers (ETL), electron block layers (EBL), hole injection layers (HIL), and other layers.

To obtain a better blue emitter, there are currently two main strategies. The first is Phosphorescent Emission (Gen-2). This uses heavy metal complexes to utilize triplet excitons, potentially allowing an IQE of close to 100 percent. The second is Thermally Activated Delayed Fluorescence (TADF)/Hyperfluorescence (HF) (Gen-3 / Gen-4). This uses organic molecules to convert triplet excitons into singlet excitons, promising high efficiency without heavy metals.

What developments there are in detail

Universal Display Corporation (UDC) plans to bring the first commercial blue phosphorescent emitter to market by the end of 2024. However, the first models could have a limited lifespan. The company is talking about approximately 50 percent of the current blue emitters, which could limit rapid distribution.

If UDC actually brings the material to market by the end of the year, the first commercial displays with pure PHOLED-OLEDs could be available as early as 2025. UDC's established customer base with AMOLED manufacturers could favor a rapid introduction.

The Japanese company Kyulux is making progress in the development of fourth-generation hyperfluorescence emitters and plans to bring a commercial blue emitter to market by 2025. These emitters offer high efficiency and a narrow emission spectrum, which could give them advantages over PHOLED emitters.

The two companies, beeOLED and Noctiluca, are developing novel material platforms for blue emitters and are expected to take another three to five years to market. It is estimated that at least 100 million US dollars are needed for the development and commercialization of a new OLED emitter, assuming the research and development is successful. It is a complex and costly endeavor that requires first-class R&D and chemical capacities, the ability to produce a large number of complete device samples, and strong business development.

Worldwide research on blue OLED emitters

Research is being conducted worldwide on blue OLED emitters. For example, in June 2024, researchers from the University of Manchester, the University of Cambridge, and the University of Eastern Finland, under the direction of Dr. Alexander Romanov, developed a new deep blue carben-metal-amide (CMA) OLED emitter material with a promising lifespan.

Researchers from the United Kingdom and China have developed a novel blue OLED emitter design based on 5Cz-BO molecules, which provides highly efficient emission with a narrow emission spectrum. These are promising results - but they are still in a very early stage.

Can artificial intelligence help?

Artificial intelligence and machine learning are increasingly being used to accelerate the discovery of new OLED materials and predict their performance. These technologies are promising, but the actual commercialization of an efficient blue emitter is still pending.

The development of a highly efficient blue OLED emitter remains one of the greatest technical challenges and at the same time a potentially lucrative opportunity for display development. Companies like UDC and Kyulux are leading these efforts, supported by emerging start-ups and academic research. The commercialization of a suitable blue OLED emitter will not only revolutionize the efficiency of displays, but also confer substantial economic advantages to the leading developers. (heh)

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