Now and then we come across small bits of information that are not quite worthy of writing up as a note, but interesting none the less.  Rather than disregard this information.  Rather than disregard it, we will put it under the subject title of “Little Bits” going forward.  Should there be feedback from readers about a particular Little Bit entry, we would be happy to dig deeper.
Shanghai Sansi Electronic Engineering (pvt), a Chinese LED lighting producer has officially announced its CoC (Chip on Ceramic)  its next generation ceramic streetlight series.  The lights have been certified in China to have a 100,000 hour lifespan (26 years at 10 – 11 hours/day or 11.4 years at 24/7).  Typically LEDs are mounted on a PCB which is attached to an aluminum heatsink with thermally conductive adhesive.  The Sansi concept is to mount the LED directly to a ceramic heatsink with no PCB, which accounts for their long life expectancy. And 67.4% energy savings over standard HID (High-intensity discharge) and HPS (High Pressure Sodium) lamps that are commonly used.  What makes this more interesting than the usual LED promo is that Sansi details the development process for this product (CoC).  Here’s what they noted, which is an indication that not all Chinese products are ‘garbage’ as has been recently stated by the current administration.  The lights are being used in a number of projects in China, particularly the Hong Kong-Zinhai Bridge that connects Hong Kong and Macao.  The bridge is 34.18 miles long with an undersea tunnel gap of 4.1 miles connected both ends to maintain open shipping lanes. 

• 106+                  Ceramic Structural Designs
• 496+                  Material Formula Refinements
• 2117+               Firing Process Trials
• 10,825              Optical Simulations
• 41,344              Performance Tests

As we noted last week LG Display (LPL) announced that they have reached the commercialization stage  of their blue OLED panels.  While these panels are not quite the final step in the blue saga, as they use a combination of blue fluorescent and blue phosphorescent material to achieve results, they are certainly a step toward the ultimate goal of a three color (RGB) phosphorescent stack (see our 5/1/25 note for more detail).  The development of this panel was conducted with Universal Display (OLED), who has been on the blue phosphorescent material development path for years and is the key supplier of red and green organometallic phosphorescent emitters to the entire OLED industry.

Why is blue so hard?
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Commercialization of a blue phosphorescent emitter and host combination that does not rely on blue fluorescent support has proved to be a daunting task due to the high energy associated with blue photons (packets of electromagnetic energy).  These excited particles can break chemical bonds in their own molecules, degrading them, or can create new non-radiative molecules that reduce the efficiency of the blue emitter.  Additionally, the host material that the blue emitter sits in has to have a higher energy level than the blue emitter itself to keep energy from leaking back to the host as heat or non-radiative energy.  So finding a blue phosphorescent emitter that meets all specifications is only part of the process, as the host material  development can also be challenging.
So, we know the development of a blue phosphorescent emitter has been difficult to say the least, as some potential blue emitter materials have high efficiency and a deep blue color point but only last for a few minutes, while others have a longer lifetime, and proper color, but are too inefficient to be used commercially, and some have excellent efficiency and a long lifetime but can’t quite produce the deep blue that is needed.  While Universal Display has completed ‘commercial verification’ with LG Display, UDC continued to record blue emitter/host revenue in 1Q as ‘developmental’, which is required until the product using the material is commercially available.  As the timeline for LGD’s panel production is still unknown, the key to understanding whether the LGD panels are being used in a commercial device will be when UDC begins recording the blue material as ‘commercial’.
What about Samsung?
Obviously, there are other OLED panel manufacturers working to bring a full phosphorescent blue emitter to market, particularly Samsung Display (pvt), who is also working with UDC along with their own development team.  As the leader in small panel OLED displays, they have a very big stake in this process but tend to be a bit more ‘purist’ when it comes to OLED processes.  SDC did not believe that LG Display’s TV panel, which uses a single color OLED and a color filter to create red, green, and blue, was the right way to produce large panel (TV) OLED in 2013 and concentrated on smaller RGB OLED displays, eventually settling on a blue OLED with quantum dot s to create colors for their QD/OLED TVs.
As the LG Display panel uses both fluorescent and phosphorescent blue emitters, we suspect that the current blue phosphorescent host/emitter that LGD is using as part of its stack might not meet Samsung Display’s requirements yet.  Samsung would likely be most interested in using blue phosphorescent material in mobile devices (smartphones and tablets) where the higher efficiency of a phosphorescent blue emitter will be key to either a power consumption reduction or an improvement in brightness, but as mobile devices have individual sub-pixels for each color, we expect their requirements might be a bit more stringent.  That said, we do expect SDC will find a way to incorporate a blue phosphorescent system in some product this year.  It could be a similar fluorescent/phosphorescent blue emitter base for their QD/OLED TV/Monitor panels, or it could be a higher specification deep blue phosphorescent emitter for an RGB architecture for mobile devices, but we find it difficult to imagine that SDC will cede the first ‘blue year’ to LGD.
All of that said, changing from a blue fluorescent emitter to a phosphorescent emitter is much more complicated than just switching materials.  In a large panel (TV), the OLED materials are deposited across the entire panel and the driving circuitry is the same for every sub-pixel point, as each sub-pixel is the same (white) color until it reaches the color filter or quantum dot.  In current RGB (small panel) displays, the driver for the red and green sub-pixel can be the same but as the driving characteristics for the fluorescent sub-pixel (blue) as different, the circuitry for the blue driver is different, adding to complexity.  In an all phosphorescent RGB display, all three sub-pixel circuits can be the same (in theory), which means not only does the material stack change, but the driver circuitry also changes, adding another level of complexity to designing an all phosphorescent display.
Timeline?
Not only do all of these issues need to be worked out, but they also need to be tested both at the pilot level and in a mass production setting, and this can take time.  The issue then becomes where do they start?  Does the OLED producer have enough ‘spare’ capacity that they can convert a line to producing all phosphorescent RGB OLED displays, or are they capacity constrained enough that they cannot afford to dedicate a line to all phosphorescent OLED production?  As was the case when green phosphorescent emitter material became commercially available, adoption took time.  With the first commercial product using a phosphorescent green emitter was released in 2013, UDC’s green emitter sales increased but then stayed relatively flat for ~15 quarters, being adopted by one of two major customers. In 2017, sales increased as a second large customer adopted the material and continued to grow quickly through 2021.  While still growing to a lesser degree, as the industry has universally adopted green phosphorescent emitter  material, growth is more tied to capacity expansion and new product applications, although the adoption of multi-layer OLED displays could lead to incremental material sales.
Adoption?
So the question now becomes will the adoption take 15 months, as it did with green or will it be faster or slower?  These are essential questions for UDC’s longer-term prospects, as while OLED capacity growth continues, the addition of a third primary material revenue stream is a godsend for any material producer.  We expect the adoption of blue will be faster, but with some caveats.
Why faster?
Numbers – in 2013 there were two OLED producers, Samsung Display and LG Display.  Tianma (000050.CH) built their first OLED fab that year but did not ship commercial product and BOE (200725.CH), China’s largest OLED producer, did not build their first OLED fab until 2016, so the adoption of green phosphorescent emitter material was dependent on only two producing entities.  Now there are over a dozen producers, all of whom are looking to differentiate their OLED displays from others and blue is a perfect differentiator.
Experience –Samsung Display and LG Display had been involved with OLED display development for over 10 years when green phosphorescent emitter material was released commercially by UDC, yet much OLED production was still problematic, and yield was always an issue.  At that time making major changes to formulas, architecture, processes, and equipment meant a long learning curve before returning to decent production yields and carrying substantial losses that could erode potential funding and adoption.  The current experience level across the industry is considerably higher than 10 years ago and producers are more likely to see a change that could give them an edge over the competition as one they are willing to take after years of managing commercial production.
Quality – A true blue phosphorescent emitter will give display designers a greater ability to balance their systems.  As a more efficient material they can maintain brightness with less power and less power means longer battery life for mobile users and a longer lifetime for the material, putting a damper on the ever-present burn-in question.  They can maintain the current power level and produce a brighter display to compete with other display modalities that are encroaching on the OLED space, or they can use blue as a differentiator that will separate their display from those without blue phosphorescent emitters.
Advertising – The idea of the display industry is to sell displays, and in order to sell displays there have to be lots of products that use them.  As the display industry can find itself in a somewhat stagnant position, with few new enticements for consumers, any new technology affords the industry a shot at incremental unit sales. We expect the industry will be enamored with the promotion of blue when it starts and will start a new line of promotion for OLED devices to counteract Mini-LED, Quantum Dots, and eventually Micro-LED displays.  However unless there is a truly discernable difference between all phosphorescent displays and what we have now, price will remain the most important factor to consumers as the blue enthusiasm wears down.  UDC however will have a new revenue stream , one that can eventually be bigger than red or green.
Why bigger?
In order to produce white light in large OLED displays, one can combine a blue emitter and a yellow/green emitter and then send the light to a color filter to create red, green, and blue sub-pixels, essentially the way LG Display’s WOLED TV panels work.  Samsung Display’s QD/OLED panel is similar but based on a blue[1] OLED material that gets converted to red and green by quantum dots. Smaller devices use individual red, green and blue sub-pixels, directly creating all colors.  WOLED displays uses UDC’s yellow/green phosphorescent emitter with a blue fluorescent emitter.  If a phosphorescent blue emitter became available, UDC would have the potential to be able to put both materials in every WOLED TV.  In Samsung’s QD/OLED the blue material used is fluorescent, with UDC providing no substantial OLED emitter material.  If a phosphorescent blue emitter became available, UDC would have that potential new stream.  In RGB display (phones, tablets) the impact would not be as significant as UDC would only be adding a third phosphorescent emitter to the two they already supply, but the volumes are extremely high, so all in, UDC benefits unless someone comes up with a better phosphorescent blue.  That said, even in that scenario UDC still has device patents that cover the use of phosphorescent emitters in OLED devices, so they might lose the OLED material sale to someone else but should still be able to capture a device royalty stream as before.
Why Not?
Cost – Fluorescent emitter materials tend to be less expensive than phosphorescent ones.  In premium OLED displays, the additional cost can be absorbed, but as one migrates to lower price tiers, the cost will be more difficult to absorb, and adoption will be slower.  We expect however that many brands will bite the bullet and eat the additional material cost in order to compete, at least for some products.  The cost of converting formulas, structure, and process also must be considered, and some who have been producing OLED displays for years at a loss might hesitate, unless they can convince funding sources to foot the bill.
Complexity – While there are certainly issues that will make adding phosphorescent blue to OLED production more complex, at least at the onset, OLED producers are so used to phosphorescent materials that they will likely adapt to required changes more quickly
 So?
We note also that UDC has contracts with all major OLED producers.  Some are based on a flat fee license, and some are based on a per unit royalty, and some cover only current phosphorescent (red & green) emitters.  In some cases UDC will have to strike new deals for blue that follow current contract formats.  While developmental OLED materials are expensive their volumes are low, but when they become commercial, they tend to be priced according to volume, so large, early adopters could have an advantage over small lower volume producers, unless their current contracts cover ‘all phosphorescent materials’.  UDC will have to balance their production cost and volume tiers against their desire to encourage blue adoption, ideally setting smaller price/volume increments in the early years against the opposite in later years. 
All in, blue is good, especially for those who produce it, but regardless of the headlines that are calling for a new ‘blue’ era in the display world, we expect most investors will expect too much too soon.  Panel producers need to make money and if they are producing at profitable utilization levels, they are going to want to keep doing so as long as possible, putting aside any changes that might reduce volume or profitability.  Most will talk the ‘blue’ talk but the implementation might be a bit less than the rhetoric.  We believe the adoption of blue phosphorescent emitter material will certainly be a positive for the industry and for the consumer, but technology hype is just that whether it is AI hype, metaverse hype, or 5G hype.  How consumers see ‘blue’ will be the deciding factor as it always is.


[1] Actually a combination of fluorescent blue and phosphorescent green.

Warning…Thinking Caps on…
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​In an OLED device, a voltage is applied to the cathode, creating electrons and the opposite electrode produces holes.  Think of them as the cute girl sitting at one end of the bar and the svelte guy sitting at the other end.  When they see each other, they are immediately attracted to each other (opposites attract) and both get up and push their way through the crowd (OLED stack).  They meet on the dance floor (emitting material) where the magic happens.  They hold each other in a warm embrace (forming an exciton, a combination of an electron and an electron hole that is in an excited state) and dance in the spotlight (produce light) until the music stops.  They gaze into each other’s eyes and quietly head back to their seats on either side of the bar.  OLED devices play out this scenario over and over as long as there is a voltage at the electrodes.

Simple enough, right?  Now let’s move this conceptual production to an industrial setting.  There are two companies in Pixeltown, both producing the same thing, excitons.  Fluorescent Inc. produces four excitons on each production run, One singlet exciton (red) and three triplet excitons (blue), but their process is old, and they are only able to sell the singlet excitons to customers, throwing away all of the triplets, leading to a 25% efficiency rating and a serious trash problem that the Pixeltown mayor is not happy about. Phosphorescent Inc. uses the same basic equipment and produces the same initial output of one singlet exciton and three triplet excitons.  However, the folks at Phosphorescent Inc hired some smart guys who came up with a way to get their triplet excitons to act like singlet excitons, which allows them to sell all three triplets and one singlet for each run, for a nearly 100% efficiency rating. 
Sooner or later the folks at Fluorescent Inc (Factory a) figured out that they are going to go out of business, having such a low efficiency rating, and the economic impact to Pixeltown would be catastrophic.   Management hired a hot-shot banker and put out  some feelers but there were no takers until the banker’s lowly assistant figured out that if you were to combine both fluorescent and phosphorescent materials together when making excitons, the result would be even better than the two individually. 
Here’s why.  If the materials are carefully matched, the ability of Phosphorescent Inc’s process to use both triplet and singlet excitons to produce light, allows some of the triplet excitons that Fluorescent Inc produces but throws away (heat rather than light), to become useful.  This means that the combined fluorescent and phosphorescent emitters could have an efficiency that is higher than 25% for the fluorescent excitons and remain at 100% for phosphorescent excitons, essentially improving the efficiency of the combination by about 15%.  Not all of the fluorescent triplet excitons can be converted and used by the phosphorescent emitter, but enough to make a difference.

Why is this important?
LG Display (LPL) made an announcement today that will undoubtedly shake up things in the OLED space, but the devil is in the details and it is essential to understand how OLEDs work in order to quantify the announcement.  In fact the structure that LG Display is speaking about is similar to the tandem system that the company uses for production of small OLED displays for ‘a large customer’.  Typically, in order to improve brightness, the dual stack approach is used, essentially squeezing two OLED stacks between electrodes instead of one.  This helps, but is an expensive solution as OLED materials, particularly phosphorescent emitters, are costly, especially if you are duplicating the entire (RGB) stack, and increases the number of steps involved in the deposition process, which has a tendancy to reduce yield.
We believe the LG Display approach is both similar in that it uses a multi-stack approach, but it is also a bit different.  We expect that the phosphorescent blue host and dopant combination that LGD is using  would not stand on its own commercially quite yet, as it could possibly fall short on a particular commercial specification, any of three major categories, lifetime, efficiency, or color point.  Developers must balance these three factors when trying to create a stable phosphorescent emitter and that has been a difficult task for all.  Materials that have the necessary color point (deep blue) might have a lifetime that is too short to use commercially or be lacking in efficiency (high power usage).  Other materials that have a more extended lifetime might not have the necessary color point.  You get the idea.  So while the concept of using a combination of blue phosphorescent and blue fluorescent emitters has promise, it is an interim solution until a truly stable blue emitter and host combination can be found. 
LG Display was careful to call this iteration ‘a step closer’ and not a final solution, but it will certainly get LG Display some acclaim and cachet from the announcement.  The response from Samsung Display (pvt) will be interesting to see as they have been working on the same blue phosphorescent emitter with Universal Display (OLED) for years and at one time, years agho, evaluated a combination blue Phosphorescent/Fluorescent combination.  We also expect a response from both the TADF community and those developing quantum dot EL displays. 
Here's the LG Display Press release: (our highlights in red)
LG Display, the world’s leading innovator of display technologies, announced today that it has become the world’s first company to successfully verify the commercialization-level performance of blue phosphorescent OLED panels on a mass production line. The achievement comes about eight months after the company partnered with UDC to develop blue phosphorescence and is considered a significant step closer to realizing a “dream OLED” display.
In the display industry, “dream OLED” refers to an OLED panel that achieves phosphorescence for all three primary colors of light (red, green, and blue). OLED panel light emission methods are broadly categorized into fluorescence and phosphorescence. Fluorescence is a simpler process in which materials emit light immediately upon receiving electrical energy, but its luminous efficiency is only 25%. In contrast, phosphorescence briefly stores received electrical energy before emitting light. Although it is technically more complex, this method offers luminous efficiency of 100% and uses a quarter as much power as fluorescence.
However, achieving blue phosphorescence has remained a major challenge even more than 20 years after the commercialization of red and green phosphorescence. This is due to blue, among the three primary colors, having the shortest wavelength and demanding the greatest energy.
LG Display has solved this issue by using a hybrid two-stack Tandem OLED structure, with blue fluorescence in the lower stack and blue phosphorescence in the upper stack. By combining the stability of fluorescence with the lower power consumption of phosphorescence, it consumes about 15% less power while maintaining a similar level of stability to existing OLED panels.
In particular, LG Display is the first to succeed in reaching the commercialization stage of blue phosphorescent OLED panels, where performance evaluation, optical characteristics, and processability on actual mass production lines should all be confirmed. The company has already completed commercialization verification with UDC.
LG Display has independently filed patents for its hybrid blue phosphorescent OLED technology in both South Korea and the United States.
The company will showcase a blue phosphorescent OLED panel featuring two-stack Tandem technology at SID Display Week 2025, the world’s largest display event, in San Jose, California from May 11th (local time).
At the show, LG Display will be unveiling a blue phosphorescent OLED panel featuring two-stack Tandem technology applied to a small and medium-sized panel that can be applied to IT devices such as smartphones and tablets. As more and more products require high definition and high efficiency such as AI PCs and AR/VR devices, the application of blue phosphorescence technology is expected to expand rapidly.
“The successful commercialization of blue phosphorescence technology, which has been called the final piece of the ‘dream OLED’ puzzle, will become an innovative milestone towards the next generation of OLED,” said Soo-young Yoon, CTO and Executive Vice President of LG Display. “We expect to secure a leading position in the future display market through blue phosphorescence technology.”
Based on LG Display’s IP here’s what we think the configurations might be…