Technical / Research - Page 12

Taiwan's National Tsing-Hua University (NTHU) Professor Jou and Dr. Wen have been developing OLED lighting technologies for many years, focusing on healthy bluelight-free OLEDs (so-called candle-light OLEDs) due to the hazards of modern lighting.

The researchers now report they have developed a new tandem-OLED device that improves the efficiency and lifetime of their candle-light OLEDs. The OLED's emission is totally blue-light free, which makes it even safer compared to NTHU's first-gen candle-light OLEDs.

Researchers from the University of Tsukuba in Japan have compared the effects of LED and OLED lighting on physical processes that occur during sleep. The researchers show that OLED exposure has a reduced effect on sleep architecture and energy metabolism.

OLED devices emits white light which contains less blue light compared to LED devices, and this does not lead to any effect on sleep architecture, but it does reduce energy expenditure and core body temperature. In addition, fat oxidation during sleep was significantly lower after exposure to LED compared with OLED. Thus OLED lighting has a similar effect to that of dim light.

Researchers from the University of Michigan developed a new electrode design for OLED devices, that can increase light output by up to 20% compared to current electrodes. The new electrode is compatible with current production processes.

The new design helps to minimize the waveguiding effect, which traps around 80% of the light produced by the OLED emitters. The researchers used a modal elimination approach, which involves optimizing the organic stack and the replacing the ITO anode with a thin film of silver deposited on a layer of copper. This kind of approach can be applied to other light emitting structures such as inorganic LEDs, perovskite LEDs, quantum dots and more.

Researchers from Samsung Advanced Institute of Technology (SAIT) developed a new stretchable OLED display, that features stable performance and high elongation possibility. Samsung says that this research is the first one to prove the commercialization potential of stretchable devices.

The new stretchable OLED was integrated with a photoplethysmography (PPG) sensor in a single device. The PPG sensor is used to measure the user’s heart rate in real-time - which can be displayed on the OLED display.

Researchers from Yonsei University developed a new OLED device that is highly stretchable. The researchers managed to build the entire device, including the substrate, conductive wires, electrodes and OLED layers, from stretchable materials.

The researchers say that this is the first time that the complete display device was produced from stretchable components, unlike previous efforts which have mainly focused on connecting small rigid OLED devices together to create a stretchable device.

Researchers from Dresden's Technical University (TUD) developed a new OLED device structure that combine vertical organic permeable base transistors (OPBT) and OLEDs materials - organic permeable base light-emitting transistor, or OPB-LET.

The new design successfully combines the function of a highly efficient switching transistor and an organic light-emitting diode. The OLED transistors (OLETs) are three-terminal devices combining a thin-film transistor with a light-emitting diode. Unlike previous OLETs, the OPB-LET offer high performance, thanks to the permeable base electrode located at the center of the device. The electrode forms a distinctive optical microcavity and so regulates the charge carrier injection and transport.

Researchers from the UK's UCL and Italy's IIT developed OLED-based smart temporary tatoos. Similar to children's "sticker" type tatoos, these small devices can be transferred to the skin by being pressed and washed with water.

Such devices could in the future be used to short-term sensors (for example to detect when an athlete is dehydrated during an event) or in fruit packaging to signal when a product has passed its expiry date.

Researchers from the Helmholtz Center Berlin for Materials and Energy and the Physics Department of the Humboldt University Berlin, together with Oreltech, developed a new flexible OLED prototype that uses Oreltech's silver-inks to deposit electrodes on PET substrates.

The researchers report that the new device outperforms ITO-based devices in both efficiency and luminance - and they are offer better bending stability.

Researchers from Soochow University, in collaboration with a wide team of scientists from China and Japan (including Prof. Adachi from Kyushu University) developed a TADF emitter material compound that features high efficiency and a narrow color spectrum.

Up until now, most TADF emitters featured a wide spectrum, which limits the adoption of TADF materials in displays as they cannot enable a wide color spectrum. To overcome this problem companies employ a structure in which the TADF emitter is combined with a narrow-spectrum fluorescence emitter (so-called Hyperfluorescence).

Scientists from North Carolina State University and the University of Texas have developed and demonstrated a new approach for designing photonic devices. The new method enabled the team to control the direction and polarization of light from thin-film LEDs, overcoming the widely known obstacles of beam shaping that arise from their Lambertian nature. Such LEDs with directional and polarized light emission could be useful for many photonic applications.

The researchers demonstrated that this approach could be used to emit directional and polarized light from an OLED devices without external optical elements.