Technical / Research - Page 7

Researchers from Korea's KAIST institute, in collaboration with Gyeongsang National University developed a new TADF OLED deep-blue emitter molecule that achieves an EQE of 33%. Combined with a fluorescent emitter to create a hyperfluorescence system, the researchers achieved an EQE of 35.4%, with mitigated efficiency roll-off. The researchers say that this is the world's highest-efficiency narrow-band deep-blue TADF OLED emitter.

To develop the new emitter the researchers introduced sterically hindered peripheral phenyl groups to boron-based TADF emitter. The resulting material, o-Tol-ν-DABNA-Me, offers a pure narrowband emission that is far less sensitive to concentration compared to standard TADF emitters.

Researchers from Germany's Karlsruhe Institute of Technology (KIT) and Shanghai University developed a new high-efficiency exciplex deep-blue OLED emitter material. The researchers say that this new materials achieves a external quantum efficiency (EQE) of 20.35% - a new world record for deep-blue emission.

The researchers explain that their exciplex strategy is based around a new molecule type with carbazole and triazine fragments linked by a silicon atom. The molecules assemble into nanoparticles which emit light in a different mechanism compared to standard single-molecule emitters. The energy levels of the electron-donating carbazole fragments and electron-accepting triazine fragments can be adjusted independently of each other to enable highly efficiency and stable red, green and blue OLED emitters.

The following is a sponsored post by Cambridge Isotope Laboratories

OLED has become the display technology of choice for many commercial products such as smartphones, laptops, tablets, TVs, automotive dashboards and wearables. OLED has advantages with improved image quality (better contrast, higher brightness, fuller viewing angle, wider color range, and faster refresh rates), lower power consumption, and simpler designs (ultra-thin, flexible, foldable, and transparent displays).

Cambridge Isotope Laboratories plant in Xenia, OH, USA

OLED, however, faces several technical challenges. While OLED TVs yield better picture quality than common LCDs, they are usually less bright. Research using a compound that has at least one hydrogen replaced with its heavier isotope, deuterium, is showing promise toward achieving greater brightness. Since the bonds between carbon and deuterium are stronger than those between carbon and hydrogen, materials made with deuterated compounds tend to have a longer lifetime, which allows OLED displays to run brighter but still last as long.

A few months ago 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 the the MPI say that in fact it is possible to develop highly efficient OLEDs with just the TADF emitter, as there's no fundamental reason or major benefits that arise from multilayer OLEDs. The researchers continue their work, and now they have developed a new single-layer blue OLED in which every injected electron is converted into a photon - or 100% IQE. This is the first time that such a single-layer OLED device was demonstrated (see image above).

The following is a sponsored post by Excyton

UK-based Excyton is happy to announce that it will showcase its novel TurboLED OLED architecture and technology at the 2023 Displayweek event (May 23-25, Los Angeles, California). Excyton has been accepted to participate at the 2023 I-Zone event.

TurboLED is a game-changing technology that offers a dramatic boost to the performance of displays. In a TurboLED OLED display, each pixel comprises deeper and lighter color red, green and blue emitters to maximize performance - in fact Excyton has shown that the TurboLED architecture leads to a 50% reduction in power consumption, a 3X improvement in emitter lifetime and an increased color gamut. TurboLED displays are especially suited for demanding applications, such as IT displays, automotive displays, gaming monitors, AR/VR headsets, smartphones and wearables.

Universal Display Corporation announced that it has acquired Merck's Phosphorescent OLED Emitter Intellectual Property (IP) assets. This portfolio includes over 550 issued and pending patents around 172 patent families with an average lifetime of 10 years, and represents over 15 years of R&D. 

The two companies also entered into a multi-year collaboration agreement, in which the two companies will create advanced PHOLED stacks based on UDC's OLED green and yellow emitters and Merck's transport and host materials.

Researchers from Carnegie Mellon University's Future Interfaces Group (FIG) designed a new haptic screen technology, which they call Flat Panel Haptics, that uses embedded electroosmotic pumps (EEOPs) that can move liquids quickly using electrical fields. 

The whole haptic layer is thin (just 1.5 mm thick) and can be placed behind a flexible OLED display to create an useful haptic display, as can be seen in the video above - buttons or keys can pop-up from the screen, and the interface can take advantage of shaped icons (like a play button or a stop button). Currently the shapes are pre-defined and cannot be altered by the user, but in the future this may change if the FPH technology is used to create small dot-matrix items.

Researchers from Australia's University of New South Wales (UNSW) have shown that OLED devices can be used to detect and map magnetic fields using magnetic resonance. The OLED is used to create a simple device, that does not need lasers like other methods used today.

This is still early research, but it could lead to the development of an OLED-based magnetic sensor, that is much cheaper and portable compared to current MRI devices. The method the researchers used is based on electrically detected magnetic resonance (EDMR) and optically detected magnetic resonance (ODMR), and is based on the change in spin behavior of electrons that are close to magnetic fields

Researchers at the University of Chicago, led by Sihong Wang (above) and Juan de Pablo, developed a stretchable OLED device that uses TADF emitters to enable high efficiency and high stretchability.

The researchers say that this is the highest-efficiency stretchable display demonstrated to date, as all previous designs used fluorescent OLED emitters. The TADF stretchable device achieves 10% EQE and a stretchability of 125%. The substrate of this new device is a newly synthesized polymer.

This is a sponsored post by Nanomatch

Using their in-house virtual design tools, Nanomatch developed a new class of emitters that enables the production of stable, fluorescent OLED devices with close to 100% internal quantum efficiency also in the blue color range.

The specific class of fluorescent emitters facilitates the generation of only singlets with radiative decay of the order of 10-8s, thereby eliminating quenching processes induced by long-lived triplets. Having filed the patent end of February 2023, Nanomatch is now looking for partners to commercialize this new concept in order to realize efficient, stable blue OLEDs on an industrial level.