Technical / Research - Page 26

In 2012 the EU launched the TREASORES project (Transparent Electrodes for Large Area Large Scale Production of Organic Optoelectronic Devices) that aimed to develop technologies that will lower the production costs of organic electronic devices.

The Fraunhofer FEP now reports that the project concluded successfully and one of the results was the development of several new transparent electrode and barrier materials. The project partners developed electrodes based on carbon nanotubes, metal fibres or thin silver - and these electrodes (some of which are already mass produced) enabled the creation of the OLED lighting device you can see above.

Researchers from Kyushu University managed to drastically increase the lifetime of TADF OLED emitters - by more than eight times. This was achieved by a simple modification to the structure of the device - putting two thin (1-3 nm) layers of Liq (a lithium-containing molecule) on each side o the hold blocking layer.

The researchers started with a TADF device, in which the lifetime is only about 85 hours (LT95). This is under "extreme brightness" to accelerate testing. With the new design and some extra modifications, the device's lifetime increased to 1,300 hours - over 16 times better than the initial device. This is a great achievement - even though this is not enough for commercialization yet.

Sonavation announced a new technology that enables to embed an ultrasound fingerprint sensor behind an OLED display. Using this solution, mobile phone makers could enlarge the display area of the mobile device, as there will no no need for a separate fingerprint sensor.

Sonavation says that their "3D biometric ultrasound technology" is the only fingerprint authentication solution that offers complex-enough imaging through a full stack display.

According to reports, Samsung is gearing up to introduce their first foldable OLED smartphone device by the end of 2016, as Samsung's mobile phone unit is under pressure to innovate and recapture its lost market share.

According to an interesting report from Korea, Samsung has been collaborating with a KAIST spin-off called Solip Technology that developed a foldable glass that will be used in Samsung's upcoming foldable OLEDs. Samsung is considering placing a strategic investment in Solip as this material is a key technology for Samsung.

Researchers from Queen's University Human Media Lab developed a prototype flexible OLED smartphone that uses active haptic feedback - or bend input - to control the device. As you can see in the video below, you can play games or flip through comic books by bending the device.

The prototype device use a 6" 720p Flexible OLED display produced by LG Display - that's the same kind of display that was used in LG's G Flex phone in 2013. The device runs Android 4.4 and includes haptic feedback motors and bend sensors.

OLEDs are nowadays facing the same issues they had since the beginning: basically, OLED materials are extremely sensitive to oxidizing agents and, especially, to moisture. This requires encapsulation materials with exceptionally high barrier properties and active fillers or getters, capable of absorbing water on a single molecule basis. The optimization of many functional properties in single encapsulating materials is a very complex materials science problem. The fact that OLED materials can also be very sensitive to heat or radiations, generates many process constraints as well.

It turns out that encapsulation materials must be specifically engineered taking into account the OLED structure, the device architecture, the chemical and physical nature of the materials and, nevertheless, the specific processes to be applied.

Researchers from ETRI (Korea's Electronics and Telecommunications Research Institute) developed transparent graphene based electrodes specifically for OLED displays.

The researchers say that current metal (mostly silver) based electrodes have a limited viewing angle because of their internal light reflection, and the external light reflection affects the image quality. Graphene electrodes are more transparent and reduce the reflectance by 40-60 percent.

Taiwan's ITRI research institute developed a long-lasting OLED blue emitter. The researchers used a green phosphorescent emitter with a new double metal structure - that emits a blue light. The so-called Plasmon-Coupled Organic Light Emitting Diode (PCOLED) structure's lasts 27 times as long as a blue fluorescent emitter.

The researchers explain that a regular green phosphorescent emitter always emits a very weak emission. By using the double-metal structure, more plasmons are generated which means a larger blue emission. This is not an up-conversion process - but merely a change in conditions within the green material. This condition was actually discovered by accident.

Researchers from Oxford University developed a new technology based on phase-change materials (similar to ones used in re-writable DVDs) that can be used to create non-volatile highly-efficient displays - similar to E Ink displays. The University established a new company called Bodle Technologies to commercialize this new technology.

The phase-change materials can manipulate light and can be used to filter, steer or dim light using very little power. Bodle already demonstrated a sub-100 nm pixel size and a very rich color gamut - they say it exceeds "other display technologies", although it's not clear what they mean by that...

Taiwan's National Tsing-Hua University has been pursuing blue-light free OLED panels for a long time, developing orange-colored (1,914K) OLED panels which they claim is much healthier than regular OLEDs or LED devices.

In November 2014, we reported that Taiwan's PMOLED maker WiseChip Semiconductors licensed technology Tsing-Hua's technology, with an aim to produce such panels by early 2015. This did not happen, but today we hear that the Taiwanese government decided to fund WiseChip development - awarding the company with 10 million NTD (about $300,000 USD) each year for two years - and the Wisechip will be able to start mass producing those 1900K OLEDs.