Technical / Research - Page 2

Researchers from the Institute of Science Tokyo (Science Tokyo) led by Associate Professor Seiichiro Izawa have developed a white OLED device that operates at the lowest voltage ever, at under 1.5 V.

The research is built upon previous endeavors in creating low-voltage blue OLEDs using an upconversion process based on triplet–triplet annihilation (TTA). The OLED device emits blue light through the TTA. The researchers doped the device with a sky-blue dopant (perylene-based dopant, Tbpe) and a yellow dopant (rubrene) which together creates white light. The researchers term these OLEDs as up-conversion OLEDs, or UC-OLED.

In 2023, we reported on research conducted at Germany's Max Planck Institute, led by Prof. Paul W.M. Blom, that looks into single-layer OLED devices. In such devices, a single TADF OLED emitter layer is sandwiched between two electrode - a much simpler design compared to commercial OLED devices that use multilayer stacks, sometimes with 10 or more layers. The researchers say that in fact it is possible to develop highly efficient OLEDs with just the TADF emitter - and have demonstrated 100% IQE single-layer devices, with an EQE of 27.7%. In 2024, the reported the highest performance TADF system.

The researchers now report that they have designed a single-layer hyperfluorescence OLED device, which is both efficient and stable. This new research was led by Prof. Blom and Prof. Wetzelaer at the Max Planck Institute.

Researchers from Sogang University, the Ulsan National Institute, Hanyang University, and Yonsei University developed an indirect method for photopatterning of solution-processed OLED emitter layers (EML). The new method does not involve any direct exposure to UV radiation or harsh etching processes. 

The new process starts by forming a sacrificial photoresist (PR) pattern, followed by spin-coating of the EML film. The next step involves converting the EML film into a single-phase network (SPN) structure by crosslinking vinylbenzyl-group-appended hosts and dopants at a low temperature, and the final step is when the pre-formed PR pattern is stripped. 

Researchers from the Russian Academy of Sciences and the Moscow Polytechnic University have developed a new top-emitting OLED device, that is based on a novel cathode design. The new cathode enables a 10-fold increase in power efficiency compared to conventional Mg:Ag cathodes.

The new cathode is based on a Mg:Ag/Ag structure, that combines a 1 nm Mg:Ag layer with a 9nm Ag layer. The researchers say that this design ensures minimal optical losses, and enhanced electron injection while maintaining high conductivity.

Researchers from India's Noida Institute of Engineering and Technology and Gautam Buddha University have developed a novel approach for the early detection of skin and ovarian cancer based on photodynamic detection (PDD), utilizing TADF OLED emitters.

The researchers explain that OLEDs are suitable for building PDD devices as they offer high mechanical flexibility, wavelength specificity, low operating volume and facile integration into wearables and endoscopic devices.

Researchers from the Kaunas University of Technology (KTU) in Lithuania, in collaboration with Ukrainian scientists, has designed and synthesized OLED emitters based on a complex formed by two donor molecules. This is the first time that emission is observed by such a complex.

This is still an early stage science, but this new emitter type could lead to simpler, more efficient, and more sustainable OLED devices. There are also applications for these materials in other areas such as sensitive detectors of picric acid.

Researchers from the University of St Andrews, led by Prof. Ifor Samuel and Prof. Graham Turnbull, working with the Li-Fi Research and Development Centre at the University of Cambridge lead by Prof. Harald Haas, have set a new world record in the speed of OLED-based communication, achieving 4 Gbp/s over a distance of 2 meters with a single OLED device.

This new record breaks the team's 3.2 Gbp/s record announced last year. The team developed a new OLED stack, by carefully selecting all the different materials, in order to increase the speed of the OLED device. 

Researchers from Korea's Advanced Institute of Science and Technology (KAIST), in collaborations with a team at the University of Incheon, have developed a flexible OLED-integrated optogenetics neural probe. Optogenetics uses light stimuli of specific wavelength to regulate neuronal activity.

The main advance in this research was the development of an ultra-thin flexible encapsulation layer, made of aluminum oxide and parylene-C, which enabled the fabrication of an ulta-thin bio-compatible flexible probe, that can sustain its operation in a biological environment rich in moisture and oxygen while minimizing tissue damage upon implantation.

Researchers from Kyung Hee University and Dankook University are suggesting two new materials (AuSq and AuSeq) as candidates for high performance OLED EIL stack materials. 

The researchers design a series of new molecules based on lithium-quinolin-8-olate (Liq), replacing the O atom with S and Se atoms. Following calculations, the researchers find that the new materials offer  faster electron hopping rate and lower injection barrier, which are expected to increase the amount of electron carriers into the EML layer, thus increasing the EQE of the OLED device. The researchers also say that these newly designed molecules hardly absorb any primary colors, thereby they don’t reduce the out-coupled light photons.

Researchers from the University of Toyama have discovered that by adding a tiny 3-nanometer wide spacer between donor and acceptor layers in exciplex OLEDs improves the energy transfer and boosts the light emission.

The researchers report that adding this spacer resulted in a 77-fold increase in EQE in exciplex upconversion OLEDs (ExUC-OLEDs), that usually suffer from poor energy transfer. ExUC-OLEDs can be driven at ultra-low voltages, which make them attractive for next-generation OLED displays.