Solution based OLEDs - Page 2

The SOLEDLIGHT (Solution Processed OLEDs for Lighting) project was launched in 2015 by a European consortium with an aim to develop cost efficient, roll-to roll (R2R) solution processed OLEDs, including their integration in prototype multiple-panel OLED lighting systems and luminaires.

The SOLEDLIGHT consortium (which is coordinated by the University of Valencia and includes OSRAM and Solvay) reported that it managed to develop multi-layer R2R solution processed OLEDs that achieved a power efficiency of 20 lm/W. This is still not up to par with evaporation-based OLEDs, but the project partners aim to achieve 100 lm/W (and 15,000 hours) by the end of 2017.

LG Display currently produces all its OLED TV panels using an evaporation (VTE) process. Market research company DSCC says that ink-jet printing is more efficient than current VTE processes as it will result in simpler displays (no need for color filters, for example, as used by LG's current WRGB displays). Ink-Jet printing will also enjoy lower depreciation costs and lower indirect expenses such as water and electricity.

DSCC estimates that an ink-jet printed 55" OLED TV panel will cost 17% less to produce compared to a VTE produced panel. An ink-jet printed panel will theoretically be significantly brighter (as the color filters absorb a large portion of the light), however solution-based OLED materials have traditionally lagged behind evaporation ones (Merck though says that the latest soluble materials are on-par with evaporation ones).

Sumitomo Chemical acquired CDT back in 2007, and since then the Japanese company has been developing it's PLED (polymer-based OLED) materials and technologies. While initially Sumitomo aimed to produce materials for displays, in recent years it has focused mostly on OLED lighting materials and even panel production.

A noted exception was Panasonic's OLED TV development project which used printing technologies and Sumitomo's PLED materials. But Panasonic terminated this project in 2013. We speculated that JOLED, which is based on Panasonic's technology (and other technologies as well), uses PLED materials in its prototypes, but we were not sure.

Last month JOLED announced that it started to sample 21.6" 4K OLED monitors. JOLED plans to develop these OLED monitors for medical applications - it will produce these in low volume at its current 4.5-Gen pilot production line, and will start mass production in 2019.

JOLED's CEO, Nobuhiro Higashiiriki, said in a conference that these first samples were shipped to Sony, which may become JOLED's first customer. JOLED says that the company managed to achieve a high quality and long lifetime, which was a challenge due to the printing process used.

Researchers at the University of California, Santa Barbara and the Dow Chemical Company have chosen a bottom-up approach to patterning emissive polymers, aiming to solve some of the problems that plague Solution-based protocols for OLED manufacture.

The team started with a layer of indium tin oxide and used light-activated chemistry to pinpoint specific locations on the surface for polymer growth. Key to the success of this approach are designer iridium photocatalysts that serve two roles: First, as the catalyst to build the emissive brush polymers, and then as a necessary dopant for the resulting OLED arrays.

In February 2017 BOE Display announced that will establish a new R&D OLED TV production line in Hefei. According to Digitimes, BOE Display is intending to use an inkjet printing process in this line, and the company already placed an order for an inkjet deposition system from Kateeva last month. BOE will use the systems to produce 55" OLED TVs.

In February BOE announced that the new line will cost 1 billion CNY (around $145 million USD). BOE will invest 80% of the funds, with the rest provided by the Hefei government. Digitimes now states that the new line will only cost 600 million CNY - so it may be that the inkjet printing line is an addition to the 1 billion CNY line (which in that case, will probably be based on an evaporation process).

Merck is going to discuss its latest soluble OLED material performance at SID DisplayWeek 2017 next month. Merck will detail the printed device efficiencies, voltages, and colors.

According to Merck, the efficiencies of its soluble OLED emitters are now comparable to state-of-the-art vapor-processed devices. Merck will also suggest a move from an evaporated blue common layer device architecture to a printed blue.

Dr. Andreas Haldi was appointed as CYNORA's Chief Marketing Office in 2016. CYNORA develops efficient blue TADF OLED emitters, and Dr. Haldi was kind enough to participate in this interview and help us understand CYNORA's business and technology.

Q: Thank you Andreas for helping us understand CYNORA's business and technology better. CYNORA has set up on a focused mission to develop a commercial blue TADF emitter. What will you consider to be a market-ready material, in terms of lifetime, efficiency and color point?

For the last 5 years, CYNORA has worked on developing thermally activated delayed fluorescent (TADF) OLED emitters. End of 2015 we started to focus on efficient blue materials, which are still a key issue for OLED displays. Compared to the red and green pixels, the blue pixel is much less efficient. An increased efficiency of the blue pixel would therefore significantly reduce the power consumption of the display.

Researchers from the University of Cambridge, the University of East Anglia and the University of Eastern Finland developed soluble carbene-metal-amides light emitting materials that were found to be very efficient and reach an internal quantum efficiency of nearly 100% at high brightness.

The new materials look like propellers and the rotation of the molecules changes the light emitting efficiency. Those materials are made from copper or gold, but the researchers aim to find similarly-shaped materials that are free from rare elements.

According to the Nikkei Asian Review, Konica Minolta and Pioneer are in talks to merge their OLED lighting business. According to the report, the two companies are finalizing the agreement, and will setup a new 50:50 joint venture in the spring.

Both companies are producing OLEDs, and the two production facilities will still be owned by the parent companies - but the OLED R&D and sales operations and will be spun-off to a new company.