Double-doping of OLED materials could double the efficiency of polymer OLED displays

Researchers from Sweden's Chalmers University have developed a new "double doping" process that basically doubles the efficiency of Polymer OLED emitter materials.

The researchers explain that doping in organic semiconductors operates through what is known as a redox reaction, in which the dopant molecule receives an electron from the semiconductor which increases the electrical conductivity of the semiconductor. The efficiency limit of current doped organic semiconductors has been limited by the fact that each dopant molecule was able to to exchange one electron only. In the new research it was shown how it is possible to move two electrons for every dopant molecule which increases the conductivity of the organic material.

Lyteus partners demonstrate the world's longest flexible OLED lighting device at 15 meters

The Fraunhofer FEP institute, the Holst Center and other partners have developed a 15-meter long OLED lighting panel, the longer OLED device ever (beating their own 2017 record of a 10-meter OLED). This work was done as part of the Lyteus, the EU's €14 million initiative within PI-SCALE.

Lyteus 15 meter OLED lighting roll
The partners in this project say that this is the first OLED produced using a new unique roll-to-roll (R2R) process that combines the performance of an evaporated OLED stack with solution processing of auxiliary layers.

Google details OLED power consumption, shows how Android's dark mode can help extend your battery life

As OLED is an emissive display technology, an OLED pixel only draws power when it is used - and the brighter it is, the more power it consumers. This of course means that adopting a dark UI is better for your device's power life.

Power consumption on the Google Pixel (2016) per color

During Google's recent Android Dev Summit, the company detailed the power consumption of the OLED display used in its 2016 Pixel smartphone (an SDC FHD 5" AMOLED). As you can see in the image above, the power consumption is different for each color (with red being the most efficient color and blue the least efficient). Surprisingly the display draws quite a bit of power even when completely black.

The Washington Post mistakenly blame OLEDs for low battery life in 2018 smartphones

The Washington Post's Geoffrey A. Fowler posted an interesting article in which he details how new smartphones are under-performing older ones in terms of battery life. Geoffrey puts 12 smartphones to the same test, and checks which ones dies first.

Washington Post 2018 OLED vs LCD smartphone power test

It is interesting that the new 2018 smartphones under performs similar smartphones released in 2017. Geoffrey's conclusion is that new display technology - high resolution OLEDs, are the culprit. The main reasoning behind that is that the iPhone XR (with its LCD display) performs better than the iPhone XS, even though the XR has a smaller display.

KAIST researchers developed a 221 lm/W orange OLED device using external scattering

Researchers from Korea's KAIST research institute developed a high-efficiency OLED architecture that uses external scattering medium to achieve an EQE greater than 50%.

OLED with SiO2 scattering layers (photo: KAIST)

Such high EQE was only demonstrated before using complex internal nanostructures or by employing a micro-lens array, but these solutions are complicated to produce and can hinder the OLEDs flexibility and planar structure. The researchers say that their scattering approach maintains the planar geometry , results in flexible OLEDs and can be easily scaled to enable low cost production.

Kyulux dramatically improves the performance of its blue HF emitter

Kyulux announced that it has developed a new blue Hyperfluoresence/TADF OLED emitter. Kyulux managed to extend the lifetime of the material and reached 100 hours at LT95 (@ 750 cd/m2) while maintaining a high EQE of 26% - 22% at 1,000 cd/m2. The emission wavelength is 470 nm.

Kyulux says that its blue Hyperfluorescence emitter is the world’s top performing material at the moment. Kyulux now aims to work together with OLED panel makers to improve the systems further by optimizing the device structure and the rest of the OLED stack in pilot production lines.

Kyushu University researchers use singlet fission to achieve near-infrared OLED emitters with >100% IQE

Researchers from Japan's Kyushu University developed a new technology called singlet fission that enables near-infrared OLED materials to surpass the 100% limit for exciton production - or achieve an internal quantum efficiency (IQE) of over 100%. Singlet fission was already used in OPVs, but this is the first time that it was demonstrated with OLEDs.

SInglet fission OLED process, Kyushu University

Achieving over 100% is possible because at 100% IQE all charges form excitons that emit light. The new technique splits the energy from a high-energy excitons into two low level ones. The new OLED emitter materials use molecules in which singlets can transfer half of their energy to neighboring molecules while keeping half of the energy for themselves - each singlet creates two triplets. The emitters emit near-infrared light.

Researchers increase OLED efficiency by over 15% by using ultra-stable film formation

Researchers from the Universitat Autònoma de Barcelona and TU-Dresden have demonstrated that ultra-stable film formation can be used to to improve the performance of OLED devices.

Ultra-stable film formation to improve OLEDs

The researchers grew (using evaporation) the organic materials as ultrastable glasses - a growth condition that allows for thermodynamically most stable amorphous solids. Testing four different phosphorescent emitters, the researchers show significant (over 15%) increases of efficiency and operational stability. The researchers also say that these growing conditions are expected to even be more useful for TADF materials.

Researchers develop a sub-electrode micro-lens array that can increase the light output in OLEDs by a factor of 3

Researchers from the University of Michigan developed a new method to cost-effectively extra more light out of OLED displays. To achieve that, the researchers used a Sub-Electrode Micro-Lens Array (SEMLA) placed between the bottom transparent ITO electrode and the glass substrate. Testing on green and white PHOLEDs, the researchers say the SEMLA enhanced light output by a factor of 2.8 (green) and 3.1 (white) compared to a similar device without the lens array.

OLED micro-lens array (Michigan)

The researcher say that such an array can be fully transparent and has no impact on the sharpness of the display. The hexagonal array of 10 μm lenses can be fabricated using conventional photolithography methods which are quite cost effective. Such a micro-lens array does not change the actual OLED production process.

Pixelligent raised $7.6 million, is working with Kateeva to adopt its materials for OLED inkjet printing

US-based high-index material maker Pixelligent Technologies announced it raised $7.6 million in a new funding round that will help the company to further drive its product commercialization and accelerate global customer adoption.

This round was led by the Abell Foundation, and included other Baltimore-based investors. This found also included strategic investments from Kateeva and Japan-based advanced material producer Tokyo Ohka Kogyo.