Disruptive Factors in the OLED Business Ecosystem
AMOLEDs have several key, potentially disruptive elements in both display and lighting technology.
by Antti Lääperi
CLAYTON M. CHRISTENSEN is known for his discussion of disruptive technology in books such as The Innovators Dilemma,1 The Innovators Solution,2 and Seeing What's Next.3 In these works, he defines two cases of disruptions: "low-end disruptions" and "new-market disruptions." The first reshapes existing markets by delivering relatively simple, convenient, low-cost innovations to a set of customers who have previously been ignored by industry leaders; the second creates new markets with new customers. Christensen also points out that disruptive innovations, at least in the near-term, have poorer product performance and underperform established products in mainstream markets, but also offer other features that new and existing customers value.
Disruptive innovations that have taken place in the display industry include an historical example that happened in two different countries in the 1970s. Researchers at Westinghouse in the U.S. and at Dundee University in Scotland separately were able to demonstrate the operation of liquid-crystal cells on glass-based TFTs. This enabled a major breakthrough.
For some time, it seemed as though OLEDs were poised to become a disruptive technology. But, in fact, now it seems that OLEDs have only some aspects of disruptive innovation as defined by Christensen. This article will examine this potential for at least partial disruption in detail.
To evaluate the innovations that are continuing to take place in the display industry, we will use the term "ecosystem thinking." Ecosystem thinking, as discussed in recent literature, such as Judy Estrin's Closing the Innovation Gap and Marco Iansiti and Roy Levien's The Keystone Advantage,4,5 enables one to see the importance of single innovations as building blocks of a bigger systemic innovation framework. Using this concept, we will show that new OLED technology has many disruptive features, which are moving from the high-end side of the application spectrum to the mainstream flat-panel business. It is still too early to say whether or not these new disruptive elements will be able to truly disrupt the current flat-panel ecosystem. OLED technology has not found a killer application in the last 10 years, although it is directly competing with TFT-LCD technology today in some areas.
TFT-LCD Flat-Panel Ecosystem Case
The first target market for AMOLED disruption involves small- and medium-sized LCDs and TFT-LCDs. These have been used in mobile phones and hand-held devices. The overall market-size estimation for these displays for 2009, according to several sources, is about 1090 million units. The share of TFT-LCDs has increased rapidly since their introduction in the early 2000s and exceeded 50% and 600 million display volumes during 2007.6 TFT-LCDs can compete with AMOLEDs in optical properties; therefore, the market size of TFT-LCDs indicates the market potential for AMOLEDs. Samsung Mobile Display estimated in August 2009 that AMOLEDs could take a 40% market share in the mobile-phone display market by 2015. The AMOLED share is now 2.3%.7 Due to the increased need to save on battery life in power-hungry smart phones, AMOLEDs have the best chance of capturing the smart-phone market first, then moving to laptops and then to thin, low-power TV screens.
OLED Ecosystem Case
In the year 2000, strong hype began over potential opportunities for OLED technology. With its excellent image quality, thinness, and response times, it was seen as a rapidly approaching challenger to existing TFT-LCD technology in small- and medium-sized displays. However, during the past 9 years, TFT-LCD technology has been able to improve performance in image quality while at the same time reducing costs dramatically due to big investments in large-sized TFT-LCD fabs. This somewhat decreased the potential for OLEDs to become a disruptive influence during that time.
Partly for the above reason, OLED technology has been without doubt less disruptive than TFT-LCD technology thus far. However, OLED technology does have some disruptive elements. The OLED stack structure is much simpler than the structure of a TFT-LCD and that offers cost-saving potential in the long run. The amount of emissive organic material that is needed in an AMOLED display is roughly 1% of the liquid-crystal material needed for the same-sized TFT-LCD. There is no need for color filters and backlight units, and color filters are a significant cost contributor for TFT-LCDs. Currently, costs for equivalent AMOLED displays are higher due to the price of emissive OLED material and the capital costs of new production lines. However, the high OLED material costs compared to that of liquid-crystal material costs are mainly due to the huge volume advantage currently held by liquid-crystal materials. Also, the current method of depositing emissive OLED material uses evaporation tech-nology, which unfortunately wastes a lot of expensive emissive material (see Table 1).
AMOLEDs in Small- and Medium-Sized Displays
AMOLEDs have been used in mobile-phone displays for 2 years now, and feedback from consumers has been relatively neutral. The marketing message has been difficult to create for companies that are otherwise mainly using TFT-LCD screens in their products. At this point, AMOLEDs have not been able to offer consumers any big improvement in image quality or battery life. In fact, power consumption for AMOLED screens in web applications has been higher than that in corresponding TFT-LCD screens. Outdoor readability has also been worse than for transflective TFT-LCD screens. In order to market AMOLEDs as a green technology for smart phones, the power consumption, including web applications, needs to be lower than that for TFT-LCD technology. This is, in fact, forecasted to happen by 2011.
Figure 1 shows the forecast for power consumption development by both TFT-LCDs and OLEDs in the years to come. The TFT-LCD power-consumpion reduction is mainly due to improvement in the efficiency of LEDs used in backlight units, and it is estimated to improve 10% per year. For AMOLED displays, the power consumption is dependent on content. Movie content typically uses only 10% during maximum power consumption, while web applications typically use 80% at maximum power consumption. In TFT-LCDs, power consumption has not been content dependent. However, it is possible to reduce the backlight while watching movies without creating noticeable artifacts in the image, using algorithms to reduce the power consumption by tens of percentages. In web applications, however, these algorithms do not provide significant reductions in power consumption.
In Fig. 1, the algorithm for web content for TFT-LCDs has been used. The large power consumption reduction in AMOLEDs is mainly due to the introduction of green phosphorescent emissive material. The lifetime of phosphorescent blue is not yet at commercial levels. The absolute power consumption is dependent upon selected luminance levels, and therefore only relative figures are indicated. TFT-LCDs and AMOLED displays are adjusted to provide the same perceived luminance. The pixel density in both displays is about 250 ppi.
Fig. 1: Projected power consumption through 2011 shows AMOLEDs gradually using less power than TFT-LCDs.9
As shown in Fig. 1, the point at which the lines are estimated to cross each other corresponds to the point in time that the power efficiency of AMOLEDs should be made better than equivalent TFT-LCD efficiency. We estimate that this can happen during 2010.
The power consumption of displays in smart phones is becoming more important becaue of two reasons. The first is that consumers prefer to look at the web from a bigger screen (while still keeping it pocket-sized), and the other is the increased time that displays need to be in active mode. This may mean hours per day. If no radical new innovations take place in TFT-LCD technology, it seems obvious that AMOLEDs will begin to achieve more and more market share in smart-phone categories. And increased volumes typically will decrease costs and prices.
AMOLEDs for TV Applications
Normal TV applications are from a lifetime point of view different from mobile-phone applications. The TV screen primarily features moving and changing imagery, and for that reason is not as susceptible to image sticking or the so-called "burn-in" phenomenon that happens over time. Therefore, concerns about lifetime and burn-in do not seem to be showstoppers for TV applications.
Lifetime is defined to be the time when luminance has dropped to half of the original value. In the case of OLEDs, different colors have naturally different lifetime figures. Blue has clearly lower figures than red and green. This can cause white-point movement over the long run, and images become more greenish. Panel makers can compensate for the lower lifetime by increasing the size of the blue cells. This reduces current density and therefore increases pixel lifetime. However, the lifetime figures are already at such a level that this phenomenon is barely visible after 10 years of usage time. More problematic is the handling of the burn-in effect. The human eye is very sensitive when it comes to observing differences in luminance levels of adjacent pixels. A 10% difference can be easily seen, while a 50% luminance reduction over the years of a screen's lifetime is hardly noticeable.
Subtitled movies and broadcasts, however, present a different challenge. In some countries, the white text is surrounded by a black box. This provides maximum contrast, but is most problematic from a burn-in standpoint and will require further studies and simulations. An initial attempt to understand the sensitivity of the text box and broadcaster's logo for OLED applications was performed using an OLED simulator developed for mobile-phone applications. This simulator is described in detail in the 2007 SID paper "OLED Lifetime Issues in the Mobile-Phone Industry." 11 For the TV simulation, the "camera" image was used to represent subtitled movies and broadcast logos and the center part of the same image simulates the moving content. Input and results are shown in Fig. 2.
Fig. 2: This TV-application simulation shows (a) a test image and (b) two color-bar result images after 6 and 30 years of usage at 10 hours/day. The degradation values show how much luminance the worst pixels lost from the original.
All the following simulations use the lifetime figures of 100,000 hours for red and green and 50,000 hours for blue. These figures are already obtainable today in panels with an output luminance of about 250 nits. It should be noted that much higher lifetime figures have already been reported, and material development companies are investing a great deal of research into increasing the lifetime figures of blue.
In both cases in Fig. 2 the TV has been "on" for 10 hours a day with subtitled movies playing all the time. The first result was obtained after 6 years of usage. A SID 2007 paper11 demonstrated that degradation levels under 5% are hardly noticeable. However, as shown above, the degradation value of 8.5% in red and green and 16% in blue cause an annoying burn-in effect. The "Camera," "Options," and "Exit" texts can be clearly seen in the color bars. In order to limit the degradation to 5% with subtitled movies, the lifetime should be 175,000 hours for all colors or the size of the blue subpixels should be greatly increased.
The second color-bar image represents 30 years of usage. This example is mainly to show how the burn-in effect can be seen over a very long run. The tiny "2M" symbol at the lower corner of the "Camera" image and the field-strength indicator at the upper left corner are simulating the broadcaster logo. Those start to be visible in color-bar images after a usage of 30 years with today's OLED materials.
The conclusion is that subtitled movies and images, in which white text is presented in a black box, seem to be too demanding for today's OLED materials. To limit the burn-in effect to less than 5% degradation, lifetimes of 175,000 hours are needed for a usage time of 6 years. It should be noted that black-text boxes are not used in all TV networks, but this study was made from a worst-case perspective. The broadcaster logo does not seem to be problematic.
AMOLEDs in Laptops
The killer application for TFT-LCDs was the laptop computer. For AMOLEDs, the situation is clearly different. Thus far, the power consumption of AMOLEDs in web applications, which are very commonly used in laptops, has been higher than that for TFT-LCDs, and due to scalability limitations, the prices for AMOLED-based laptops have been far too high. The power-consumption obstacle looks to be solved in the near future, as shown in Fig. 1, but cost and price will remain issues for some time.
However, a preliminary simulation analysis was performed to review the laptop application from both a lifetime and burn-in sensitivity perspective. The simulator developed for mobile-phone applications was used8 by selecting three input images and a color-bar image to show the results of a burn-in analysis. The test images and result images are shown in Fig. 3. The lifetime of emissive materials were 100,000 hours for red and green and 50,000 hours for blue.
The resulting image suffers a maximum of 4% degradation for red and green pixels and a maximum of 7% degradation for blue pixels. Burn-in effect in the resulting image (color bar) is almost invisible. The corresponding figures after 8 years of usage are 6% for red and green and 11% for blue. The burn-in effect is slightly seen after 8 years of usage. The first and second test images represent menu screen and stationary text pages, respectively, and the third one represents moving content. This needs to be further analyzed in the future, but this preliminary result already shows that laptop applications are very valid for AMOLEDs, provided that scalability issues enabling price reductions are solved.
Fig. 3: These laptop test images show results after 5 years of simulated usage.
AMOLEDs in PC Monitors
PC-monitor applications are in many ways close to laptop applications, except that power consumption is not so critical, and the PC monitor business is more price-sensitive than the laptop business. Usage-time expectations of PC monitors are longer than in laptops. In PC monitors, the screen typically goes to screen-saver mode if there is no activity. This is a good practice from an AMOLED point of view, as long as the screen saver is not using a stationary image. The same tool8 was used to simulate PC monitor usage from an AMOLED burn-in perspective.
Degradation values have increased to 9% for red and green and to 16% for blue pixels. The runtime in Fig. 4 was 10 years. The burn-in effect caused by text input is now visible. The degradation results after 6 years of usage are 5% for red and green and 10% for blue. The burn-in effect is not easily noticeable.
OLEDs in Lighting
Recent developments in the efficiency of emissive materials have opened totally new applications to OLEDs. The linkage between AMOLEDs and emerging OLED-lighting ecosystems is the development of highly efficient emissive materials and the optimal solution to outcoupling efficiency issues. OLED lighting will be in many ways a very disruptive technology, much more than OLEDs in the display industry. It will afford architects and interior designers totally new ways to design lighting. Instead of point light sources, distributed light panels can be used, including color variations. Also, this disruptive technology is coming from the high-end side, meaning that it does not involve the creation of new markets, but will disrupt the way in which lighting is designed in homes and in public places in the future. It can be assumed that lifetimes over 100,000 hours will be obtained, resulting in 23 years of operational lifetime, if the lighting is used an average of 12 hours per day throughout the entire year. Maintenance and repair issues need to be taken into account, but those most probably will not be any kind of showstoppers. The reduction of illumination to half its value might be observable, reducing the operational lifetime to 10 years or requiring 200,000-hour half-lifetimes. We may even see OLED lighting used in the backlight units of TFT-LCD TV screens before AMOLED scalability issues are solved. LED lighting will be used to replace light bulbs and halogen lamps in the near future for power-saving reasons, but OLED lighting will bring about a new way to design lighting.
TFT-LCD and OLED case studies have shown that many elements of the industry follow or are forecasted to follow Christensen's disruptive theory.9 To make the theory comply with case studies for the display industry, an extension – high-end disruptions – is proposed to be added as the third element of the set of definitions concerning disruptive innovations. Examples from the display industry show that disruptive technology can come to the business ecosystem also from the high-end side, i.e., more expensive in the beginning, but offering something customers appreciate and are ready to pay more for. For example, a wall-mounted flat TV was a dream of people for a long time, and TFT-LCD TVs were able to come close to living that dream. Now, LED-based TFT-LCD TVs are flater, and OLED-based TV will bring even thinner structures, brilliant colors, and contrast with a wide viewing angle and low power consumption.
Fig. 4: Test images demonstrate PC monitor results after 10 years of usage.
The inventions that produced TFT on glass and combined that with liquid-crystal cells formed a disruptive innovation in the late 1970s. These innovations took place in the U.S. and in Europe, but Japanese companies were still able to take the lead in TFT-LCD technology and disrupted the entire display industry in the U.S. and in Europe. The killer application for this disruptive technology was notebook computers. Costs at the time were much higher, but the flatness of the screen was something consumers would pay more for. TFT-LCDs disrupted the CRT business with lower quality, but with a higher cost structure.
AMOLEDs have disruptive elements and are challenging the TFT-LCD ecosystem from the high end with lower power consumption, brilliant colors, a wide viewing angle that does not cause a loss in contrast ratio, and a thin and simpler structure. Displays will be for some time more expensive, but in the long run OLEDs seem as if they will be less costly to produce than TFT-LCDs. The competitive advantages seem to support AMOLEDs in taking a substantial market share, first in small- and medium-sized displays for handheld devices. AMOLED power consumption is, however, dropping below the corresponding TFT-LCD power-consumption figures in demanding web-page applications. This will enable manufacturers to create a green marketing message and will enable smart-phone manufacturers to design AMOLEDs into their products in larger volumes than that to date.
A further observation is that AMOLEDs are ready to be used in laptops and in PC monitors as soon as scaling can enable cost reductions. Lifetime and burn-in sensitivity are close to acceptable levels based on the preliminary analysis reviewed here. However, more studies and simulations with laptop-oriented content are required. The same observation is valid in the case of the PC monitors. Lifetime and burn-in sensitivity do not seem to be obstacles in taking AMOLEDs to this market.
A preliminary study was also performed for TV applications. Moving content and the logo of the broadcaster do not seem to be problematic from a lifetime and burn-in sensitivity perspective, but black text boxes with white letters will make the worst possible contrast for the screen and will require a further increase in the lifetime of the emissive material or a reduction in the contrast by some other means in the smart receiver itself.
In short, the key OLED technology elements with the potential for disruption (as compared to TFT-LCD technology) are the use of active materials and the ability to achieve lower power consumption by 2010. Another possible disruption may occur in the area of lighting. All of this, of course, relates to the green aspects of the technology, which will almost certainly drive the OLED ecosystem of the future.
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4J. Estrin, Closing the Innovation Gap. Reigniting the Spark of Creativity in the Global Economy (McGraw-Hill, New York, 2008).
5M. Iansiti and R. Levien, The Keystone Advantage. What the New Dynamics of Business Ecosystems Mean for Strategy, Innovation, and Sustainability (Harvard Business School Press, Boston, Massachusetts, 2004).
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7DisplaySearch, Alternative Display Technology Report: OLED Technology (2006).
8A. Lääperi, Discussions with leading emissive OLED material supplier and leading AMOLED panel makers (2009).
9A. Lääperi, "OLED lifetime issues from a mobile-phone industry point of view," J. Soc. Info. Display 16, No. 11 (2008).
10A. Lääperi, I. Hyytiäinen, T. Mustonen, and S. Kallio, "OLED Lifetime Issues in the Mobile-Phone Industry, SID Symposium Digest38 (2007).
11A. Lääperi and M. Torkkeli, "Disruptive Innovations and Innovation Ecosystems in the Display Industry," ISPIM 2009 Conference (June 2009). •