Technical / Research

Researchers from Korea's UNIST institute, together with colleagues from Sungkyunkwan University have developed a new OLED intermediate layer material (with a highly unusual structure, twisted EBMs with anisotropic molecular arrangements) that significantly improves the brightness, efficiency and lifetime of blue phosphorescence OLED devices.

The researcher report that the new materials enable to reduce the operating voltage of the OLED display, thus enhancing the power efficiency by 24% and the operational stability by 21%. The researchers say that this new material can also be used for in-organic LEDs (including microLEDs).

Researchers from LORDIN, in collaboratioon with researchers from Korea's Dankook University, Gachon University and Hongik University, have reported on a highly efficient and stable ultra-pure blue phosphorescent OLED emitter, based on Lordin's Tetradentate Pt(II) material Complex with a vibration suppression effect.

The researchers say that the new emitter offers a lifetime of 451 hours (LT50 at 1,000 cd/m²), and an EQE of 25.1%. The emission spectrum is extremely narrow - full width at half a maximum of 22 nm. The researchers further developed a tandem OLED device based on this new emitter, which achieves an EQE of 50.3% and a lifetime of 589 hours (LT 70).

Researchers from the Fraunhofer IPMS, together with colleagues from the Max Planck Institute for Multidisciplinary Natural Sciences (MPI-NAT) are developing OLED-based optical stimulators for future cochlear implants.

The researchers explain that optogenetics is a method that uses light to control genetically modified cells in living tissues. By introducing light-sensitive proteins into cells, their activity can be precisely turned on and off with light pulses. This technique is commonly used in neuroscience to study the functions of nerve cells and to activate or inhibit specific neuronal populations.

Researchers from the University of Michigan has developed an OLED device that converts near infrared (NIR) light into visible light and amplifies it more than 100 times. Compared to current night-vision systems based on image intensifiers, this device could enable a much more efficient and light-weight solution. 

The OLED device integrates a photo-absorbing layer inside the OLED stack, that converts infrared light into electrons. Those electrons are converted into visible light photons via the OLED layers - about five photons are created for each electron, and some of these photons are re-absorbved, converted into more electrons, and then even more photons, creating a great amplification of the absorbed NIR light. 

Researchers from Shenzhen University and Wuhan University have designed new white OLED devices that exhibit exceptional power efficiency (over 190 lm/W, 39% EQE) and extended operational lifetime (LT80 446 hours at 1,000 cd/m²). 

The new device uses a blue TADF emitter emitter combined with a yellow MR-TADF emitter. The light is a warm white light. The researchers also used the same technique to create a standard white emission device, that still achieves a high EQE of 35.6%, thus further validating the strategy.

Researchers from Kyung Hee University in Korea have designed highly efficient stretchable OLED devices by incorporating the prestretched elastomer with optical adhesive film.

The researchers say that the so-called Geometrical Stretchable OLED (GSOLED) device enhances the efficiency of the OLEDs with the light extraction phenomenon brought by nanowavy corrugated structures. Furthermore, GSOLED shows stability in stretchable conditions and displays narrower emission spectrum with improved color purity.

Researchers from National Taiwan University, together with colleagues from Yuan Ze University, National Dong Hwa University and Academia Sinica, have developed a very high efficiency blue TADF OLED device, by adopting a favorable horizontal oriented host material.

The researcher designed a new host material (4Ac26CzBz) that is made from acridan and carbazole moieties linked to a benzimidazole core. The host material exhibits a wide optical gap (Eg) and high triplet energy (T1) of 3.3 and 3.0 eV, respectively. The researchers used 4TCzBN as the blue-light TADF dopant, and report a remarkably high device external quantum efficiency of 35.8 % (59.8 cd/A and 62.8 lm/W) and a low turn-on voltage (<3 eV). The device features with significant suppression of the efficiency roll-off, maintaining a high efficiency of 29.7 % as luminance at 1000 cd/m².

Researchers from Korea's KAIST, in collaboration with Dong-a University and ETRI have developed a new stretchable OLED structure that is made from 3D rigid islands, or bumps. These so-called 3D-Pop islands remain unchanged as the display itself stretches and so maintain excellent performance.

The OLED islands are connected with parts that are curved in shape (similar to a horseshoe) that can be deformed while still operating normally, even at 500% tension. The whole structure can simultaneously utilize hinge-type rotation and tension of the bending connection connector, and is so not limited to a 2D plane. Even at 40% elasticity, the light emitting area remains at 85%. 

Researchers from ETH Zürich and the Huazhong University of Science and Technology developed a new scalable fabrication technology that enables the deposition of extremely small OLED pixels. The so-called nano-OLEDs achieve a pixel density of 84,000 PPI, or even higher. The pixel size is around 100 nm, the smallest pixels ever reported.

The method is based on direct nanomolecular patterning of the OLED materials, realized by self-aligned evaporation through nanoapertures fabricated on a free-standing silicon nitride film adhering to the substrate. The researchers report that the average nano-OLED EQEs is up to 10%. 

Researchers from Tsinghua University in Shenzhen, China, have managed to dramatically increase the stability of OLED devices by the adoption of deuterated host material.

The researchers, led by Prof. Man-Chung Tang, have designed and synthesized deuterated anthracene-based hydrocarbon PNA as the new host material. The researchers have observed that the faraday loss decreases with the increase of the deuteration degree.