Power consumption - Page 1

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.

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 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.

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.

Researchers from Taiwan's National Tsing Hua University (NTHU) developed a new TADF OLED emitter material that maintains its high efficiency at high luminance. The researchers say that this new material is the world's most efficient TADF emitter at high brightness.

The new material is made from two diboron-based molecules, CzDBA and tBuCzDBA. These donor–acceptor–donor (D–A–D) type and rod-like compounds concurrently generate TADF with a photoluminescence quantum yield of ~100% and an 84% horizontal dipole ratio in the thin film. The researchers synthesized a green TADF emitter that achieved a a high external quantum efficiency of about 37.8% with an efficiency roll-off of only 0.3% at 1,000 cd/m².

ETNews posted an interesting article, claiming that Samsung Display is developing a new TV technology that combines OLED emitters with quantum-dot photo-luminescence materials. The basic idea is to use blue OLED emitters and then convert the blue light to white light using quantum-dots combined with color filters (QDCFs) to add red and green colors.

Samsung OLED TVs (2013)

This seems to be a rather complicated design, but it could be much easier to produce compared to a true RGB OLED TV, as there is no need for precise OLED patterning. This is similar to LG's WRGB OLED TVs which use a white OLED source (made from yellow and blue emitters) and color filters on top.