Technical / Research - Page 16

Researchers from RIKEN, the University of California, San Diego and others have developed a new mechanism to enhance the efficiency of OLED devices. The basic idea is to manipulate the electron spin to control the OLED exciton formation - basically lowering the OLED voltage so that only triplets and formed instead of a combination of singlets and triplets.

The researchers demonstrated this principal using an organic molecule called 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), placed on a metal-supported, ultrathin insulating film. By measuring the emission spectrum, they could monitor the exciton type - and show that at a low voltage, only triplets are formed.

The Holst Centre announced that it will show several new fingerprint sensor innovations at Display Week 2019 next week. The research center will show a new high-resolution (500 PPI) under-the-display sensor that uses the Center's proprietary collimator technology as well as an in-display sensor concept that uses photolithography patterning to integrate the OLED and organic photo diodes (OPD) pixels side-by-side.

The Holst will also showcase a new over-the-display (suitable for LCDs) transparent sensor which at 70% the center says is the world's most transparent fingerprint sensor.

OLED driver maker MagnaChip launched its latest 28 nm OLED Display Driver IC for smartphone displays. MagnaChip says that it is using the world's most advanced process for OLED drivers, which enables it to achieve a 20% reduction in form factor compared to its previous 40 nm process.

In addition to the size reduction, the new process also enabled MagnaChip to reduce the voltage from 1.1V to 1V, which reduces the power consumption by more than 20%, and it also reduces the EMI levels (again, by 20%) which improves the phone's call quality.

Researchers from the Korea Advanced Institute of Science and Technology (KAIST) developed a self-powered wearable and washable OLED display device. The whole device is fabricated on textiles and the efficient OLED devices are driven by polymer solar modules.

Both the OLED device and the polymer solar panels are sensitive to moisture and oxygen, and regular OLED encapsulation will not protect such a device when washed. The researches designed a new washable encapsulation barrier using both ALD and spin coating. The device is flexible (curvature radius of 3 mm) and survived 20 washing cycles of 10 minutes each with little change in performance.

Professor Homas Teets from the University of Houston has been awarded a $589,000 National Science Foundation (NSF) CAREER Award to explore new synthetic strategies for producing photoactive organometallic compounds.

Specifically, Teets will use the award in three research areas - efficient and long-lasting blue OLEd emitters, near-infrared (NIR) emitting compounds and photocatalysts for organic synthesis capable of light-induced electron transfer. The grant will also fund educational projects aimed at children from kindergarten through high school.

TCL unveiled that the company is developing a new hybrid display technology that uses a blue OLED emitter coupled with red and green QD emitters. All three emitter materials will be combined and printed using ink-jet printing technology. TCL calls this technology H-QLED and this could prove to be the technology of choice for TCL's future high-end emissive TV displays.

It seems as TCL believes that commercial-level red and green QD emitters will be achievable in the future, but blue QD emission will be more difficult to develop, and hence it will rely on OLED emitters. TCL did not disclose more details - but this R&D effort is being performed at the company's Juhua Printing platform.

In 2014 we reported that the Tai-Yah (also called Atayal) tribe, the "dark tribe", has started to test National Tsing-Hua University's blue-free OLED lighting panels (produced by WiseChip).

These early candle-light street OLEDs were not suitable for that environment, and NTHU researchers say that mountain dew rapidly shorted the wires. But not NTHU has stepped up its efforts and teamed up with First-o-Lite to produce a new version of its panels. This time the researchers are positive that its new panels will enable the entire village to adopt blue-hazard free lighting,

US-based OLED material developer Molecular Glasses received a $225,000 SBIR Phase I grant from the National Science Foundation to develop non-crystallizable charge transporting organic materials as OLED functional layers and thermally activated delayed fluorescence (TADF) emitter-layer hosts.

The NSF explains currently used OLED host molecules tend to crystallize and are poor solvents for the emitting molecules leading to decreased light emission efficiency and shortened device lifetime. Molecular Glasses' innovation uses isomeric mixtures of designed molecules that are amorphous and non-crystallizable in all three layers.

Researchers from the University of Southern California (USC) led by Mark E. Thompson (who was the first to report on efficient phosphorescent OLEDs, later commercialized at UDC) developed a new copper-based phosphorescent OLED emitter compound, that could have several advantages to the currently-used iridium compounds.

The researchers say that copper-based emitters could be cheaper (as iridium is an expensive and rare element) - but more importantly could be the key to develop an efficient and long-lasting blue OLED emitter.

Researchers from Italy's ISOF-CNR, University of Naples "Federico II" and Università di Modena e Reggio Emilia have developed new organic n-type FET transistors based on CVD graphene sheets. The researchers say that the new process and materials they used can enable flexible, transparent and short-channel OFETs - which could be used in the future for OLED or OLET displays.

To create the new transistors, the researchers used thermally evaporated thin-films of PDIF-CN2 (a perylene diimide derivative, specifically Flexterra's ActiveInk N1100) as the organic semiconductor for the active channel of the transistor, with the single-layer CVD graphene (grown at Italy's IIT INSTITUTE) as the electrode material