Technical / Research - Page 2

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, in collaboration with OLEDWorks, 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.

During iMID 2024, Samsung Display's eVP Yi Chung said that the company plans to reduce the power consumption of its OLED panels by over 50%. SDC is developing several technologies, each contributing to the same efficiency goal.

SDC did not detail its plans exactly, but it did mention some of the new technologies it is working on - polarizer-free OLEDs (these have been commercialized already), multi-frequency driving (demonstrated by other OLED makers), tandem OLED architecture and the adoption of high efficiency blue PHOLED emitters.

A report from Korea says that LG Display has successfully developed an OLED panel that is based on a blue phosphorescence emitter. The blue PHOLED, provided by Universal Display, offers 100% IQE, up from 25% used by current fluorescence emitters. This will result in around 20-30% power saving for the display itself (depending on the images shown).

UDC has been developing blue emitters for many years, and recently the company said that the development will take a few more months and won't be ready in 2024. The main challenge is increasing the lifetime of the materials. However LG Display has adopted a tandem design to enable a commercially ready display, perhaps even sooner than UDC planned.