Welcome, everyone. My name is Michael Myer. I'm with Pacific Northwest National Laboratory. Welcome to today's webinar, OLED Lighting Products, Capabilities, Challenges, Potential brought to you by the US Department of Energy's Solid State Lighting Program. Presenters today include Naomi Miller and Felipe Leon. Naomi Miller straddles the line between design and engineering at the Pacific Northwest National Laboratory in Portland, Oregon. By bridging the gap between technology and application she promotes the wide usabilities working with industry to overcome hurdles, and celebrate the opportunities. Felipe Leon is an electrical engineer with 14 years of experience in product development testing and product management. He worked on Kodak's OLED business group and was product manager for a solid state lighting small business for four years.

Felipe joined PNNL in July of 2014 and is a contributor to the OLED research currently managed under the solid state lighting program. And now on to our presentation.

Good morning out there in webinar land. This is Naomi speaking. We have a presentation on organic light emitting diodes, which is what OLED stands for today. The outline is in front of you there. We're going to introduce what panels are about and the drivers that control them. We're going to talk about dimming. We're going to talk about efficacy and what happens over time with efficacy. Color performance. We're going to talk about the options that you can get at this point in time with panel sizes. We're going to talk about light output and maintenance and life and lighting quality issues. But we will also talk about the realities of what OLED's competition is at this point in time and the market hurdles that OLEDs have to face.

We are recognizing that OLEDs are a technology that is still emerging. And you have to remember back in the good old days of LEDs when they were new and really lousy and most of us had no confidence that LEDs would make it in the marketplace. Well OLEDs are a little bit in that same camp. It's a technology that's also going through some of the same growing stages that LEDs went through with great promise. The Department of Energy's Solid State Lighting Program has put a focus on OLEDs recently to try to help that market develop and grow and be recognized.

We have, so far, three stages in the first development. One was a GATEWAY demonstration project of Aurora Lighting Designs' installation of OLEDs which you see in the photograph on the right hand side of your screen. And that report on that installation was put on the website, I believe in March of this year. Then there was an overview report on the technology that was put on the website in May or June of this year. And this seminar is really addressing the issues that came up in that report. We have a third report that's probably going to come out in September based on independent testing of off the shelf OLED products and PNNL tear-downs of some of those products.

So we have learned an awful lot about how current OLEDs in the market are performing. And we have another GATEWAY study in the works that will follow probably later in the year or early next year to talk about how OLEDs are continuing to perform. Felipe, tell us about how OLED panels work.

Thank you Naomi, and thank you Michael for the introduction. I'll spend the next few minutes talking about OLED lighting panels in general, some of the important considerations of designing with this novel light source, how to drive and how not to drive them, and lastly, I'll talk about some of the performance characteristics that have been observed and that you can expect as you incorporate these OLEDs into your lighting products. So in general how do OLED lighting panels work? OLEDs respond to a current driven through them by emitting light and is the result of recombination of the organic layers. And the waves on the wavelength of light emitted is dependent on the properties of the organic material or materials used.

So to create an OLED panel, first you need a substrate on which to coat the organic layers. And these are sandwiched between two electrodes. Glass is the most commonly selected substrate material. In a bottom emitting device, in other words, a panel that the light is emitted through the substrate on which you coat materials, a transparent anode, typically indium tin oxide or it's referred to as ITO, is applied directly onto the substrate glass. This is followed by your organic layers and lastly by reflective metal cathode for one sided nontransparent products. An interesting application is if you can in manufacturing coat a transparent cathode that allows for light emission potentially through both sides if you cover the back with the glass.

So as you'll see here, in order to protect, in the figure on the right, in order to protect the OLED from moisture and oxygen, some form of encapsulation approach is needed. That diagram shows a pocketed cover glass with a desiccant. The alternative such as metal and thin film encapsulation may also be used. Most commercial OLED panels today also apply a film on the substrate that improves the light out coupling resulting in improved efficacy while also eliminating reflective characteristic of the panel and providing for more uniform appearance over angle. The end result of all this is a sheet of light that is uniform and pleasant to look at. Some will some refer to it as glare-free.

Manufacturers of OLED panels known to supply the US market include LG Display, OLEDWorks, which acquired Philips' key OLED assets in 2015, Kaneka Corporation, Konica Minolta, and MC Pioneer, which is a joint venture between Mitsubishi Chemical Corporation and Pioneer Corporation. While no standard exists for OLED panel sizes or shapes, the most commonly observed sizes are shown here. Mostly rectangular, though round options exist and polygon options have also been observed. So as noted the in previous slide, manufacturers of OLED panels take great care in assuring that OLEDs are protected from environmental factors that can degrade them. Despite those efforts, a failed edge seal due to either manufacturing, mishandling, or application can result in unappealing artifacts such as what is shown on the two pictures on the top right of this slide.

The left image represents a panel as intended, uniform light. The right image shows a panel where the glass on glass seal was placed under stress and resulted in a failure of the seal and moisture ingress that resulted in dark spots. Some thin film encapsulation techniques have been developed and are being explored though little is known about the robustness of these. Also noted previously was a use of a light extraction film on the surface of the light emitting glass. The benefits of which are shown here. You have color consistency improvement over angle and improved panel efficacy. While on some applications a mirror finish may not be desirable, the mirror finish of an OLED with this light extraction film may be a positive in some applications. However the trade-off in performance must be kept in mind.

While OLED panels that emit white light are most common, panels designed to emit in various colors can also be obtained, and a product marketed in 2011 by Verbatim was color tunable and could also be tuned to emit white light. While no truly flexible or formed OLED luminaires have been observed in the US market, flexible panels are starting to be marketed and will create exciting opportunities for outside the box thinking when it comes to luminaire design. In order to emit light the OLED panels require a power source that can deliver preferably a constant current. In general the OLED panel manufacturer will provide typical and maximum current drive conditions and a voltage range that would be typical under those drive currents.

In designing a luminaire, OLEDs are generally placed in series to assure the same current is flowing through all the panels up to the range capability of the driver being used. Constant current drivers are able to guarantee a constant current to the load provided it falls within a range of voltages specified. It may be tempting to maximize the voltage range of a driver into luminaire design by placing as many panels as possible in series and getting real close to the maximum rated voltage for which a constant current is guaranteed. However, as you'll see, as panels age, the voltage across them for a given current increases. And some overhead must be designed into the luminaire design in order to avoid tapping out the driver which could lead to light loss due to both the natural efficacy loss of the OLED panel plus a reduction in current as the OLED power draw requirements increase.

Interestingly enough, this voltage rise is a good indicator of the decay that's been experienced by the OLED panels and may be used to manage end of life. For example, flicker the display momentarily at turn on once the end of life has been reached or it could also be used to maintain a constant light output over time through a feedback circuit. LED drivers are a convenient off the shelf option for delivering a constant current to OLED panels though they may not always be the best choice in particular where dimming capability is desired. Furthermore, daisy chaining of drivers, as seen in the graphic below, have been encountered and observed to result in very low overall efficiencies. The first driver in that daisy chain converts the AC source into DC voltage while the second driver uses the DC voltage output of the first driver to deliver a DC current to the OLED panel. And the combination has been observed to result in very low efficiencies in some cases.

OLED drivers may be a better alternative in some applications as they are typically optimized for appropriate dimming of the OLED panels, may have programmable currents that are adjustable to the specified current recommended by the OLED manufacturer, and also provide some features to protect the OLED or manage end of life. Of course a well-designed driving circuit specific to the luminaire design may provide for optimal efficiency. So in choosing drivers, some considerations must be given to the impact the selection will have on overall system efficacy. Since OLED panels do not typically require or use optics or suffer from thermal losses, the drivers are essentially the only sources of loss in the luminaire design with the exception if some optic is placed such as a cover sheet of plastic that would further reduce some of the efficacy of the luminaire.

So the driver should be selected or designed to allow for some voltage overhead to cover the expected increase in voltage for the specified current to avoid an accelerated degradation. OLED luminaire makers should consult with the OLED panel manufacturers regarding the expected voltage increase at end of life. Also, if designing a system with some smarts, consider if end of life management may be appropriate for your luminaire. We've discussed some of those ideas and some others are possible. For designs that will require dimming, the method by which the OLED it is dimmed needs to be considered when selecting or designing a driver. LEDs have a fast response time and mostly Pulse Width Modulation is used to reduce the overall current points of the LEDs.

Given that OLEDs are large in area, internal capacitance can cause a Pulse Width Modulation approach dimming to happen. Unexpected or undesirable behavior such as noticeable flicker or in poor designs, current spikes that may reduce the panel's lifetime. The Pulse Width Modulation approach maintains a constant current during the time it is on. In LEDs this is ideal as it ensures color consistency over the dimming range especially as LEDs dim to cool, a characteristic that is considered undesirable. OLEDs on the other hand, benefit from improved efficacy as you go down in current and have been observed to warm as they dim, typically considered a desirable characteristic. So for the reasons noted here, adjustments of the current is a preferred approach for dimming outlets, while it is noted that some products on the market have been designed to dim using Pulse Width Modulation. In some cases flicker has been observed. And we'll talk a little about flicker later in the presentation.

So what I have here is simply a slide that shows performance from spec sheets or testing. Panel efficacies ranging from 29 to 60 lumen per watt are claimed in product spec sheets. And you can see here that the system efficacies of some of the products that were evaluated in CALiPER testing range from 21 to 44 lumen per watt. And as we also discussed there is a power draw increase over time. And what was expected based on conversations with manufacturers is that in some cases up to 33% more power at the end of life may be required to maintain the initial current. The importance of informing customers regarding this is to ensure that lighting and dimming circuits are designed with end of life power draw in mind and to ensure that energy code compliance is met.

So in this slide we're talking about dimming controls protocols and flicker. So we talk about dimming in the sense that the power that goes out to the OLED is controlled via either Pulse Width Modulation or by the reduction of current. However an OLED driver must also be designed to accept the dimming signal. For example a zero to 10 volt, DALI, or DMX and then translate that signal and use either Pulse Width Modulation or a constant current reduction to dim the OLED. Most market-available OLED luminaires dim only to about 10% light output though drivers exist that can dim to 1% or less. But it appears that most of this is a system designed cost consideration. As we discussed, flicker can be introduced through Pulse Width Modulation dimming unless frequency is high and/or your modulation is slow. Constant current reduction dimming can help you reduce the potential for flicker. And Naomi please, thank you for driving and I'll turn it over to you.

OK, well I want to go back to the previous slide because I have to congratulate Felipe for going through OLED, DALI, DMX, PWM, CCR etc. PDQ. Very good job. Thank you. OK, this slide is a summary of OLED panel characteristics. These numbers came from manufacturers' literature, not from CALiPER testing, for example. And the full panel information is in the OLED capabilities report that we're referring to that's online for you. The panels that are described in this particular table are the ones that are shown in the bold font at the top square. So for example all of the panels described under LG Display panels are 100 millimeters square and all matte finish. Most of the OLED panels that we see from LG Display are matte finish. OLEDWorks has a combination of matte and shiny finish. And Kaneka Corporation products that are available are all shiny finish at this point in time. I'm going to go into this a little bit more a little bit later.

The color characteristics of OLEDs are different from those of LEDs. You're used to a signature of LEDs having a peak in the blue and then a dip in the cyan and then a single hump that rises off in the yellow green portion of the spectrum or yellow orange portion of the spectrum. There are actually a few more pumps visible in the OLED spectrum. We have seen a couple of different spectral power distributions of the OLEDWorks panels and the LG panels for which we have data are similar except that there are differences in color characteristics. They can range from 3000k to 4000k. Some of the panels are down at a 78 CRI. Some are as high as 89 CRI. The RF values, if we're looking at TM 30, the fidelity value is as low as 78 in some panels and as high as 86 and others. And the Gamut value ranges from 95 to 98.

Now what that basically means is that this is a very good color rendering light source. However it tends to under saturate red hues just a bit. And those red hues are important for skin tones and for retail applications. So although it's good there's a little bit of under saturation in that particular area of the color wheel. Characteristics of the OLED panels are different from anything we've seen before. Primarily it's very thin, half a millimeter up to two millimeters panel thickness. But that thickness or thinness I should say, doesn't include the connectors, or mounting the hardware, or any frames around the panel, or any drivers. So you have to recognize that although this panel is very thin and small and light, then you have to figure out how to get the driver and the wires to that panel in order to illuminate that panel.

So there's definitely a two component system to worry about here. When you have remote drivers that add some complexity to the installation, so if you are specifying these products you need to plan for the number of wires that need to be pulled from the drivers to each individual OLED panel. There are some drivers that can drive multiple panels. In some cases you'll end up with one driver per panel. It depends on the system that you're looking at. So talk to your manufacturer. On the horizon, and we are seeing these flexible OLED panels which is going to give us so much increased freedom in what luminaires can look like. They may be bendable, foldable, they may be printed on a plastic substrate, or they may be on bendable glass substrate. The plastic gives you a lot of flexibility. However, plastic is somewhat more permeable to air and water, oxygen and water, which can cause the OLED layers to degrade more rapidly.

One advantage of having the bendable glass is that it's much less permeable to water and air. So the life of the OLED is expected to be a little bit longer with glass. Here are some of the trade-offs that you get from different kinds of panels, looking at light output, lumen maintenance, and life. And we're looking specifically at the most common panel that's available on the market right now which is four inches by four inches, or approximately 100 millimeters square. Surprisingly, compared to LEDs, what's on the market for OLEDs right now is primarily 2,900 to 3000k. So it's actually the warmer color temperature that's available. And it is generally more efficacious than the higher color temperature panels that are available. But the trade-off between luminance, lumens, and life is something that you want to keep in mind.

So for example, here is a panel from LG Display. It's about 2 and 1/2 watts. That's the panel itself. That doesn't include any losses from the driving system. So that panel itself, that four by four panel is producing about 75 lumens at that 3000 candelas per meter value. 3,000 candelas per meter is approximately half the brightness of a fluorescent lamp of old P12 technology. P8 technologies are somewhere in the neighborhood of about 10,000 candelas per square meter just looking at the surface of the lamp itself. So 3000 is very easy to look at. Very tolerable, easy brightness to look at. And the estimated life to L70 which means the point at which the panel has degraded in light output by 30%, that is expected to be about 40,000 hours at that luminance value, that brightness level. And you're getting about 55 lumens per watt for the panel itself.

If we look at the OLEDWorks panels, there are two brightness values that have published information. One of them is also at about 3,000 candelas per square meter. And that's about 115 lumens coming out of that panel with an estimated 50,000 hours life and about 46 lumens per watt. If you use a driver that is driving at a higher current you can get out of the same panel 300 lumens. And the brightness goes up to 8,300 candelas per square meter. But the compromise is you really shorten the life of the panel down to about 10,000 hours at L70. And the efficacy is reduced as well, down to about 42 lumens per watt. Kaneka is different in that it doesn't have an extraction layer on the surface. So the extraction layer takes an OLED panel from being a shiny panel to a matte panel. That's the same brightness, same luminance from each viewing direction.

The Kaneka panel will not have the same luminance at different viewing directions because it doesn't have the extraction layer built into it. That is producing about 60 lumens from the panel at 3000 candelas per square meter, at about 50,000 hours life. But lower efficacy because it doesn't have the extraction layer on it. Now I should mention that OLEDWorks also offers their panels in the shiny finish, which is a really interesting finish to look at. So it's there for artistic purposes but they also offer it with the extraction layer so it'll have the whiter, more matte finish and higher efficacy output with the extraction layer built in.

Let's talk about lighting quality issues that move beyond efficacy and luminance and all of those other metrics. If you look at OLEDs, the potential is there to produce a very different quality of light. So for example, Konica Minolta produced a large number of curved OLED panels for this display of tulips for a festival a year or two ago. And it was absolutely beautiful. You can see the panels or that the tulips each have three curved OLED panels building up each tulip bloom itself. The tulips didn't last very long. They didn't glow very long. The life was admittedly short. But you can get a sense of what the artistic capabilities really are. So those patterns can lead the eye. They can work in wave finding, for example. Very, very creative kind of medium.

Now an alternative that we are seeing in architectural products now is to use those OLED panels as tiles of light. And you can configure those tiles in different ways to create really interesting patterns in the ceiling. The one you're seeing on the lower right is from Aurora Lighting Design in Grayslake, Illinois. It was one of the first offices to be lit with OLED panels from Acuity Brands. So you can see that the tile configuration, you can produce words or playful patterns with these tiles. You can create signage. Or you can use the OLED panel as a background for signage, for example. You can also incorporate OLED panels into room surfaces or build it into furniture so you can have glowing walls, and glowing ceilings, and glowing furniture panels. All kinds of capabilities. You can use OLED panels to create dimensional sculptures, which is something we see illustrated in the Philips Lumiblade sculpture. Lumiblade is now owned by OLEDWorks. And then in the lower left, you're seeing a task light that is offered by AriLight out of Canada using a single panel producing a very, very soft, almost shadow free task lighting.

Now the light distribution from OLED panels is pretty consistent at this point in time. It's kind of a blob distribution, formally called the cosine distribution. And that cosine distribution has the property of having the same luminance or visual brightness from any viewing angle as long as you're looking at the lighted panel side. It's very interesting. This cosine light distribution emits a lot of light at high angles. So if zero degrees in this photometric polar plot is straight down and straight out to the sides is at 90 degrees, it's emitting more candelas at higher angles, between about 60 and 90 degrees, than classic lighting that we're used to seeing from either fluorescent or from LEDs. This distribution can help light vertical surfaces.

And it also lights faces because they emit light at those angles at which faces and the higher parts of walls are normally illuminated by a luminaire. It makes the space look brighter, it provides softer shadows in the space. It's almost like having an indirectly lighted space even though the panel is producing all of its light downward. That same high light emission has its downside. It can produce a perception of glare if the luminance is too high relative to the adaptation level of the viewer. So for direct viewing, some luminaire manufacturers such as Acuity Brands Lighting have limited the luminance of the products they offer, the OLED panels, to about 3,000 candelas per square meter. So that you can look at it comfortably without glare.

As soon as the luminance gets higher than that you can start encountering glare which can be modified by a light fixture. You can put lenses and louvers in and filters to change the light distribution. But as soon as you do that, you reduce the efficacy of the product. So at this point in time, in order to not reduce the efficacy of the product and take advantage of the lightness and thinness of that product, no lenses or louvers have been applied at this point in time. Another great opportunity that OLEDs have to offer is that because they're low in luminance and very soft to look at, they can also provide very soft, flattering light on faces and bodies.

So think of mirrors, either in lavatory spaces, or in dressing rooms, in retail applications, hospitality spaces, anywhere you want faces and people to look really good when they're looking at themselves in the mirror. The panels do need to be low luminance so that they're not glaring to the person who is looking at themselves in the mirror. And they need to be spaced a distance away from the face reflection. Otherwise you end up with disabling glare that can actually prevent you from seeing your own face. So there's a little bit of a balancing act, but it has great potential. Lighting uniformity is something you get from a lighting system that produces a very soft general lighting like OLEDs can.

And this is back to the installation at Aurora Lighting Design. It's interesting that when we interviewed the people who work at Aurora Lighting Design, they responded that they really loved the OLED lighting in the space for general lighting. And it was very comfortable, very soft, didn't cause harsh shadows, but they said it can be dull unless you combine it with task lighting or accent lighting for visual highlights. Very much the way that an all indirectly lit space can feel. Kind of that cloudy day effect. So I think you can see between the photograph on the left and the photo on the right, it's obviously the same space, but what Aurora has done is switched on some accent lights and some task lighting in the right hand photograph. And that makes all the difference. That adds a little bit of visual pizzazz that helps overcome that cloudy day effect that you might get from the OLEDs.

Now let's talk about maintenance issues. When you look at L70 life for these panels, the estimated life ranges from about 10,000 hours to 100,000 hours depending on how hard you're driving the panel. At 3,000 candelas per square meter, the approximate life, depending on the manufacturer and all the conditions, is about 40,000 hours. And if you're looking at an office space that operates at about 4,000 hours a year, that's about 10 years of operation. If you're driving those panels higher at 8300 candelas per square meter, they;re lasting about 10,000 hours. So that's 2 and 1/2 years. This means that in 2 and 1/2 to 10 years, you're going to have to look at replacing some panels.

So you have to think about maintenance when you're specifying OLEDs. Will the panels be replaceable in the field? Will the panel replacements available at that time be of exactly the same luminance, the same color, will they have the same connectors? Are they easy to replace? Do you have to think about static electricity issues when you're replacing a panel, for example. And will janitors or will other people replacing these panels be able to know to take any precautions that are necessary in changing these panels? There are also shipping and installation issues with OLEDs. These glass panels, they're so far glass panels, they can be fragile. And if they're shipped in the luminaire, there can be bumps along the way. All shipping involves some bumping of the product before it gets to the job site.

And we have actually seen some panels getting damaged in transit. So it depends a lot on the packing quality from the manufacturer. It also depends on whether there was anything built into the fixture that could jostle that panel and cause any kind of breakage along the edge that would cause a compromise in the OLED panel. System cost is still an issue. Some task lights are available that are fairly affordable. They're not cheap but they're affordable. Most OLED products that are on the market are still considered specialty items because of the system cost even if they are available through a retailer, for example. But panel costs are dropping.

And we are starting to hear about mass production methods that may decrease those costs dramatically in the near future. And when that happens, you're going to see OLED products adopted much more readily. Until then the economic viability is strained, especially compared to LED technology which has undergone a dramatic drop in product cost over the last 10 years. And unless you've been living under a rock for the last 10 years, you're fully aware of that. OLED's competition: edge-lit LEDs are the principal competition right now. They are thicker than OLEDs. Some are about 9 millimeters. So that's quite a bit different from one millimeter. But they offer higher luminance, longer life, and higher efficacy in many cases compared to the OLED. And if they are edge-lit LEDs, especially if they're made out of acrylic, they may be more durable in shipping than the glass that's in OLEDs.

The next technology that we want to watch for is MicroLEDs. Those are in development right now. We have heard that Apple which is putting OLEDs into their Apple Watches I believe for 2017, is looking at changing over to a MicroLED technology in 2018. So we are expecting there's going to be a lot of R&D funding put into MicroLEDs in the near future. Then something that's available now on the market is printed LED sheets and strips. Interesting technology, the technology is shown from Nth-Light there on the bottom. That's still low enough efficacy and limited CRI and CCT offerings at this point in time. It's not a uniform array of LEDs. It's kind of got a bit of a random pattern, but we are expecting that this is a technology, because it's printable, that's also going to improve dramatically in the next few years. So OLED has some competition.

So let's talk about where OLED's opportunities really are. One manufacturer is working on a pedestrian friendly luminaire. And if you put OLED panels inside a well sealed luminaire, it could be a really perfect application for an outdoor luminaire because you can use a panel that is low luminance. Most pedestrian friendly luminaires need to be low in luminance in order to not be too glaring. And it doesn't need to put out a lot of light and you don't need a sophisticated distribution of light in all pedestrian luminaires. That's an option. Signage we talked about earlier. Glowing clothing. Vehicle bodies. You may see not just the tail lights glowing from now on, but you may see the body itself glowing. Windowshade, anything that you can use at night that may help simulate daylight. Shelf lighting for retail applications and back lighting for retail applications is going to be a big application once we can get larger panels available. Luminous wallpaper especially if we can get that field cuttable. Combinations of LEDs, which are really good for point sources and OLEDs , which are really good for area sources combined in a single luminaire are a great option.

And Acuity Brands has shown one product already. You can use OLEDs like ceramic tiles if you have electrified frames. You can have floating luminous planes in lieu of ceilings. And that can be a separate lighting layer that may not have all of some of the other systems stuff that you have to run through ceilings like electric wiring. You may have dynamic shape changing luminaires, when we have bendable, curveable luminaires. Put them on servomotors and have them flopping around like fans overhead. And then, in case you're lighting a starship, in case you've been watching any space program for the last 40 years-- maybe it's 50 years now since Star Trek, right-- every holodeck, every interstellar bar has glowing bar tops. So there's a huge opportunity for everybody. So remember that for your next starship.

We do have some market hurdles. It's still very costly for routine applications, which is why we're not seeing it competing for recessed two by fours and two by twos. It's still, in many cases, too low for many workhorse applications, too low luminance. It's still poor in efficacy so it's not something that you want to use as a light engine at this point in time. There are clunky remote drivers that are really too large to be integrated into the sleek OLED luminaire. Lack of interchangeability of panels and drivers among manufacturers. There just aren't enough manufacturers and no real standardization at this point in time. Panels are somewhat delicate to replace in the field. There are very few drivers optimized for OLED systems at this point in time. And we hope that's going to change soon. And we don't have any standards out there for testing life and lumen maintenance. So some parts of LM-79 apply to OLEDs but not all. It does mean that we're going to have to have some standardization going on at the IES level I think. LM-70 does not apply to OLEDs.

Now we have a classic chicken and egg problem with OLEDs. I come from Portland and therefore I know the name of my chicken. His name is Collin . I do not know the name of the egg. But designers don't want to specify OLEDs because they are expensive, and unfamiliar, and not competitive with contemporary technologies. And manufacturers don't want to make OLED luminaires because designers aren't specifying them. So we are at an awkward point with OLEDs where we need to get both specifiers specifying them and more manufacturers incorporating LEDs into their products so that we can get faster development of the technology. Summary: OLEDs are struggling through a very similar set of difficulties that LEDs had in their early days. But OLEDs are a creative medium that are starting to be available for lighting designers.

They have wonderful properties for facial modeling and cheerful wall luminances, low glare applications, shatter-free task lighting. They do have their growing pains in terms of efficacy, and cost, and standardized connectors, limited optical distribution at this point in time-- it's basically a cosine distribution-- and drivers borrowed from the LED industry. So we need to see drivers that are really optimized for OLED use. Tomorrow however, they may offer dynamic options that we've never experienced before. So stay tuned. Don't wait for your next starship to specify them. Try specifying them now so you get some experience with them. Thank you for your attention. And Michael, I think it's time for you to bombard Felipe and myself with some questions.

Yes Naomi, thank you very much. We received a handful of questions about the cantina from Star Wars and the proper way to light it. So we'll save those to the end and come back to those. We did receive several questions. One of them hearkening back to your comment about the wallpaper or similar to that concept about the wallpaper and also about the size, what are the actual size limitations? This person is wondering how large can they get and what does that entail as they obviously get larger and larger, what type of issues would you run into?

Felipe, you can probably answer that best.

Sure, so the size limitation really deals with the IR drops that are encountered on these panels. You have to drive current from an edge. And then you also have to consider the fact that as your current is going into the panel without creating some kind of grid structure or lines that some luminaire designers just don't truly appreciate in their light source, you really can have the potential for current to be different at the edge of the panels than it is at the center. That just causes the light output to not look uniform in some cases. So that's really the challenge.

It seems like the standardized size seems to be somewhere in the range of about a foot at max from what I've seen. 30 centimeter by 30 centimeter. Or the panel size that seems to be becoming the de facto standard for smaller panels seems to be in that range of 150 millimeters. Of course having multiple panels in a luminaire, a good way to go. It minimizes risk. It's easier to replace one panel than to replace one large panel. But certainly the desire is that if we can make them larger and certainly we can put them on some kind of large flexible sheets, that could lead to some very good products and I hope that that's also explored by the manufacturers.

Great, thank you for that. We have another question about that related to edge. But we'll come back to that in a second. The next question would be is the market for OLEDs commercial or more of a residential or does it fall between either of the markets?

I guess I can take that question. I think it can be either way. Much of the task lighting market is residential as well as commercial. And that may be a great way to introduce the public to OLEDs. The OLED products that we're seeing from Acuity Brands, interestingly enough, are marketed both through commercial venues, through architectural representatives, for example, and are going into commercial applications. But they're also marketed through Home Depot for example. So we're seeing those aimed partly at the home market. So I think both ways.

Great, and following up, more of a personal question: the commenters were wondering, do you have any actual OLEDs out of your homes right now?

I do not.

I do not.

OK great. So we can talk about those reasons another time as well. So building on that, the size limitation that you were talking about earlier, Felipe, and either you can answer this question, but the larger question relates to lumen depreciation. Does it occur evenly? Let's say if it's a roughly a half foot by half foot panel. Is that going to evenly decrease or is lumen depreciation going to happen maybe from the edge and work that way one way or the other like a gradient? So the larger question is how does lumen depreciation actually appear in this panel light source?

My experience has been that lumen depreciation is in a well sealed panel will be uniform throughout the panel from edge to center. However, whenever lumen depreciation is caused by for example, some small moisture ingress from the edges, if it's not leading to significant dark spots it's possible that your edge can start getting eaten away at first. But that would almost be unnoticeable unless it's a major issue. And it's likely that you're also encountering dark spots at that point so that point will be moot. But my experience is that it happens from center edge, it's very uniform depreciation.

Great. Naomi, I'm going to direct this one to you knowing that your background in research and related to glare, what is the tolerable limit for luminance values for direct view luminaires?

It depends on the adaptation level of the viewer. But I will say for example, that Aurora Lighting Design found that they dimmed down the panels to about 65% of their maximum luminance most of the time. We found out that there had accidentally been a higher wattage driver installed when the fixtures originally went in. And it turned out they were consequently dimming down the fixtures from about 4,000 candelas per square meter down to below 3,000 candelas per square meter, partly in response to a glare response. And that was at night. So it could be that 4,000 or slightly higher luminance was a little bit above their threshold, at least when they were adapted to the lower brightness environment at night. So at 3,000 candelas per square meter, they didn't express any concern about glare at all or discomfort.

Thank you. Not surprising that adaptation layer matters. Back to you Felipe, for more of a construction and design material question. The person looking for essential a matte, low-reflection type of OLED or surface, how does it make it matte, or what is the extraction layer and what ultimately makes it matte versus shiny?

So the extraction layer that we talked about are basically a layer such as brightness enhancing film that's used for LCD displays. And when it's done, it's done at the manufacturer's site. So not even the luminaire designers are typically applying this directly. So in the case where you have a shiny surface, you've probably already made a trade off and have the desire to have a reflective surface on your product. Otherwise, you could just go ahead and get it with a light extraction film which provides you that diffused matte appearance and also gives you the enhancement of angular viewability being consistent as well as the increased efficacy of the panel itself. So I have not heard of instances where either the luminaire maker or a customer themselves are putting a film on top of the OLEDs.

Good to know. Thank you. Naomi, I'm going ask you to put your Carnac the Magnificent hat on and project into the future. Two questions here: one is do you we look at OLETs and notice how I tried to us a T there, Organic Light Emitting Transistors, as well as LEDs replaced CFLs. When will OLEDs possibly replace LEDs?

I'm not sure OLEDs will ever replace LEDs. They're entirely different. LEDs are really good at directional lighting, narrower beams for example, and it's a little bit easier to control the light coming out of an LED because it's a much smaller source. OLEDs are really an area source, so I don't expect them to replace-- well the only thing they could replace is perhaps a two by two panel that is edge lit with LEDs at this point in time. Do I think that's going to happen soon? If indeed OLEDs can be increased in efficacy to above 100 lumens per watt, yes. I think they'll start to replace those kinds of LED area sources.

But I think in the meantime it's going to be a light source that's used in combination with LEDs. I think you want LEDs to do what they do best and OLEDs to do what they do best, and combine them in either separate lighting systems or combined lighting systems to get exactly the light distribution and appearance that you're looking for. In response to your question on OLETs, I don't have an answer. I don't know what the answer is, but I can find out.

And just to add on to that, Michael, I would guess that if it's a high efficacy technology, some of the funding opportunity announcements that DOE puts out are good ways to try to get some of that advancing. So I don't know there are any out there in particular for OLETs, but maybe some of the lighting ones will be applicable if they are light emitters.

Great, thank you. We have a handful of other questions coming in now. I'm going to take this last one and direct this toward you, Felipe. This is a larger question. It's more about market analysis. Basically the commentary here is asking why is it market research seems to be not consistent across the board? Here they're referencing to two specific reports both with the target date of 2020 and one projection of many million dollars and another one of a few billion dollars of OLED penetration. So obviously, the magnitude difference there but ultimately I guess from your experience doing forecasting and other types of things, why do companies have different answers sometimes?

These are research companies and their forecasts are only as good as the data that feeds their models, is my suspicion. And the problem right now is possibly that there are just too many factors to consider. One of them is there is no killer app, no real application that really just drives home and says OLET. OLET is your only choice. When we look at what happened with LEDs, the reason that it was easier to kind of project that market and see how they were going to overtake the market was that they were really a high efficiency source overtaking a very low efficiency source.

And as the costs came down, the adoption rate would go up. Right now OLEDs are competing with fluorescent, they're competing with LEDs. They're really high efficiency sources as they are. So they have to fight something different. And trying to model basically just the mass adoption or significant adoption of a technology in that kind of competitive market, maybe it's challenging for some of the research companies to really nail it down. And a few years back I saw a report relative to what you're saying. That one single report said yeah, it could be a low market, very niche, just one or two companies. It could be a medium market or it could be a large market. And it was kind of difficult to kind of see that report and kind of say OK, you decide. I understand it's a struggle. Please Naomi.

I just wanted to say that sometimes when you see those optimistic reports, they are talking about OLED displays, Not OLED lighting. They are similar technologies but OLED displays are different in that they only have to last a few thousand hours. OLED lighting has to hold up for a much longer period of time. So it's kind of a different technology. But Felipe, correct me if I'm wrong.

Just be aware that some of those reports could be incorporating OLED displays into their projections. And that market certainly has had great success. In particular Samsung has. I think nearly all of their mobile displays are made with OLEDs.

Great. At this point we are now pushing into the next hour. We're always very conscious of everyone's time. So we are ending the question and answer at this point. Thank you for attending the Department of Energy's Solid State Lighting Program on OLED Lighting Products, Capabilities, Challenges, and Potential. And thank you, enjoy the rest of your day.