Technical / Research - Page 13

Researchers from Osaka University developed the best performing heavy-metal-free room-temperature phosphorescence (RTP) OLED emitters.

The researchers say that the new emitter (called SiAz), made entirely out of carbon, hydrogen, nitrogen, and silicon atoms, combines the mechanisms of TADF and RTP to create an efficient emitter system.

Researchers from Kyushu University reported that they have developed a promising new blue OLED emitter system, based on a two-unit stacked tandem hyperfluorescence OLED with improved singlet-excited-state energy transfer from a sky-blue assistant hetero-donor-type TADF (HDT-1) dopant.

The research reports that the new emitter system offers a pure-blue color (CIE 0.13, 0.16), a narrow spectrum (full-width at half-maximum of 19 nm), an EQE of 32% at 1,000 cd/m² and a lifetime of 18 hours LT95. The lifetime is still lacking, but with stricter control of device fabrication and procedures the researchers say they expect that device lifetimes will further improve to rival commercial fluorescent blue OLEDs.

Researchers from the Imperial College London have devised a method to create strong chiral light emitting polymers OLEDs. These OLED devices emit efficient polarized light - which means that they could be used to create OLEDs without an anti-reflection polarizer filter and thus enable higher efficiency displays.

The researchers discovered that using thin films of aligned polymer LED devices shaped like fusili pasta it is possible to emit high chirality light.

A couple of months ago we reported that researchers at UDC developed an OLED device with plasmonic decay rate enhancement that dramatically increase device stability. It turns out that UDC filed for two new trademark applications that seem to hint it is aiming to commercialize this technology.

The two trademarks at PLASMON PHOLED and PLASMONLED, which both of course indicate that these are emitters that adopt plasmon technology.

Researchers from Canada's Polytechnique Montréal and the Université de Montréal developed a new near-infrared (840 nm) TADF OLED device that is 300% more efficient than existing ones. The IQE of the new deice is 3.8% - which is the best all-organic OLED emitter ever developed above 800 nm.

Photograph of the Polytechnique Montréal crest taken using visible and infrared illumination. Credit: Pr Sébastien Kéna-Cohen

To create the new OLED device, the researchers developed two new organic compounds - and were inspired by a class of molecules previously used for biomedical imaging.

Researchers from the University of Michigan, in collaboration with Universal Display are developing a low-cost roll-to-roll (R2R) process to produce flexible OLED lighting panels. The goal is to achieve a panel cost of less than $10 per klm - a tenfold reduction compared to current costs.

The roll-to-coll system can continuously produce encapsulation panels, at high speeds and reduce costs. The front plane (organic stack) deposition is done via OVPD. The researchers say the will demonstrate reliable, encapsulated 25 cm² flexible white OLED panels with an efficacy of 50 lm/W and a CRI >85 on barrier-coated plastic films or thin glass.

Researchers from Stanford university in collaboration with Samsung's Advanced Institute of Technology (SAIT) developed a new OLED structure that enables resolution of up to 10,000 PPI, high brightness and a cost-effective production process.

In the new so-called Metaphotonic OLED structure, the panel is produced on a base layer of reflective metal with nanoscale corrugations. This 'metasurface' can manipulate the reflective properties of light and thereby allow different colors to resonate in the OLED sub-pixels.

Researchers at Penn State University, with funding from the DOE, suggest a new way to improve the light extraction from OLED devices (EQE). The idea is to introduce electrically inert and low cost "dilution" molecules to the hole and electron transport layers, and so reduce the reflection of these layers which increases the outcoupling efficiency of these layers.

The added molecules do not degrade and actual performance - and should not increase production costs. The researchers are currently modeling and simulating molecules and device stacks. Eventually, the researchers aim to demonstrate multi-stack OLEDs with internal light extraction efficiency exceeding 75%.

Researchers at Universal Display, developed an OLED device with plasmonic decay rate enhancement that dramatically increase device stability. By including a nanoparticle-based out-coupling scheme to extract energy from the plasmon mode, the researchers managed to maintain the device efficiency.

The device used an archetypal phosphorescent emitter to achieve a two-fold increase in functional stability at the same brightness as a reference conventional OLED device and extracted 16% of the energy from the plasmon mode as light.

Researchers from North Carolina State University developed a new technique that could drastically lower the cost of ultrasound acoustic imaging, using OLED displays. The researchers say that ultrasound receivers could be made with costs of around $100 - compared to current systems which cost $100,000 or more.

The researchers fabricated an OLED on top of a piezoelectric transducer. When ultrasonic waves interact with the transducer, it lights up the OLED display. This create a very simple ultrasound device compared to current devices.