Technical / Research - Page 4

Researchers from the Fraunhofer IPMS have developed a semi-transparent high resolution OLED microdisplay, that is significantly lighter than conventional combiner-based optical see-through near-to-eye systems. The specification of the display was not disclosed, but one can see it's a monochrome yellow panel.

The Fraunhofer researchers developed a new semi-transparent OLED-on-silicon microdisplay technology, which enabled the new display. The technology is based on modern and advanced silicon CMOS processes, applied to silicon-on-insulator (SOI) wafers. The new wafer technology can be used to implement very thin circuitry layers. With the help of a specific IC design and an appropriate transfer-to-glass process flow, the transparent OLEDs were enabled.

MicroLED Connect, our hybrid event series focusing on the microLED industry, will be hosting a two-day virtual event focused on the OLED innovations, technologies, manufacturing, markets and more. The online event will take place next week, on April 10-11, and will be an excellent opportunity to learn the latest OLED updates and connect with industry professionals on our excellent online event platform.

Today we have published the agenda for this event, with 20 exciting talks by leading OLED developers, supply chain companies and top-edge researchers. This will be an excellent opportunity to learn and connect with the OLED industry. You can register for the event here, with a yearly pass to MicroLED-Connect (with an option to also include entry into our September on-site event in Eindhoven, The Netherlands). Our members also gain access to past event recordings.

Researchers from the University of St. Andrews in the UK, led by Professor Ifor Samuel and Professor Eli Zysman-Colman, identified the key processes controlling the efficiency of TADF OLED emitters under high brightness. This could assist material develops on their quest to design materials that maintain high efficiency at high brightness.

The researchers explain that OLEDs have lower efficiency at higher brightness, and in many TADF materials, the efficiency roll-off is severe, so that the high efficiencies achieved at very low brightness are not maintained at higher brightnesses needed for displays or lighting applications. For the first time, the researcher identified the key processes controlling the triplet population, and propose a figure of merit for efficiency roll-off.  

Xiaomi announced a strategic partnership with Lumilan, an OLED materials developer. Lumilan, with support from Xiaomi, built a new R&D lab in Ningbo, China, to develop new materials targeting smartphone display applications.

Xiaomi aims to get early access (or perhaps exclusive access) to novel OLED material to enhance its competitiveness. It is likely that the two companies aim to develop new OLED stack materials and perhaps new OLED emitters (Lumilan already develops TADF emitters).

OLED lighting developer OLEDWorks announced that it has been awarded a $8.6 million US army project to develop high-performance OLED microdisplays for consumer and defense applications. The display is targeted specifically towards head-mounted display applications in the AR and VR markets.

OLEDWorks says that its microdisplay platform offers high brightness, full color, and excellent lifetime. The company says that it is developing three OLED microdisplay products. The company's displays are based on OLEDWorks' proprietary multi-stack (3, 4, and 5-stacks) OLED technology to OLED microdisplays.

Researchers from the UK's Northumbria, Cambridge, Imperial and Loughborough universities developed a new Hyperfluorescence OLED emitter system based on a new molecular design, which is highly efficient and simple to produce.

The researchers explain, that in Hyperfluorescence  systems, the elimination of the Dexter transfer to terminal emitter triplet states is the key towards OLED efficiency and stability. Current devices rely on high-gap matrices to prevent Dexter transfer, which unfortunately leads to overly complex devices from a fabrication standpoint. The researchers developed a novel molecular design in which ultranarrowband blue emitters are covalently encapsulated by insulating alkylene straps. 

Researchers from CEA-Leti and the Université Sorbonne Paris-Nord (USPN) developed a new OLED structure that enabled them to achieve two new world records for OLED-based data communication, a bandwidth of 450 Mhz and a transmission throughput of almost 3GB/sec. This more than doubles the previous OLED record. The researchers say that this proves that OLEDs can play a role in future fast photonic-based data communication, which was limited to in-organic microLED devices up until now.

The researchers developed a new OLED structure, in order to find the best compromise between speed, light performance and device size. The researchers used evaporation to deposit 7 layers of various organic materials while precisely controlling how they fit together and stack. The whole device is only 40 um in size.

Researchers from Korea's Gachon University, Seoul University and Chungbuk University developed a multi-functional encapsulation technology that can be used to develop fiber-based wearable OLED devices, deposited on textiles.

The new OLED device is produced on a light extraction substrate, that is super-hydrophobic - developed by coating a water-repellent layer on a rough surface obtained through ion beam treatment, ensuring excellent uniformity and easy power control. The new encapsulation offers high performance (10-6 g/m-2/day) and also achieves a UV transmission rate of less than 3%.

Researchers from the UK's National Physical Laboratory (NPL), together with the Samsung Advanced Institute of Technology (SAIT), released a new study to better understand the degradation of blue OLED devices. 

Close-up of the OrbiSIMS instrument’s vacuum chamber showing the nozzles of the ion beams and electrode that extract ionised molecules for analysis (Picture credit: NPL)

The OLED degradation mechanisms that limit the lifetime of blue OLED emitters, whether physical, chemical or something else, are still not yet fully understood. Understanding the degradation mechanism of blue OLEDs is essential to improve their performance and stability. The NPL / SAIT team used OrbiSIMS, an innovative mass spectrometry imaging technique invented at NPL in 2017, to study OLED degradation. 

Researchers Durham University, led by Professor Andrew Monkman, discover new OLED emitters that offer high performance in a hyperfluorescence emission system. The main new material, a molecule called ACRSA, was found to triple the efficiency of hyperfluorescence OLED devices.

These OLED emitters aren't actually new - they were studied years ago, but were found to be poor emitters. That was true when used as OLED emitters, but when used in a hyperfluorescence system (which combines both fluorescent and TADF emitters), these were surprisingly efficient. The ACRSA emits a green emission, but deep blue light emission can be achieved by transferring ACRSA's energy to a blue terminal emitter. This approach reduces exciton energy compared to direct blue emission in devices, allowing more stable, longer-lasting blue OLEDs.