OLED Application to Large Displays; Compare with Other Display Technologies Abstract Oled technology is an incredibly powerful technology that is redefining the display industry. I will discuss the basic operation of Oleds, different types of Oleds, current and future display technologies, the advantages, disadvantages, and the current and future applications. by Josh Klemond 4/22/16

Outline Overview Types of OLEDs Current Display Technology Advantages of OLEDs Disadvantages of OLEDs Applications http://www.extremetech.com/wp-content/uploads/2013/10/lg-flexible-display-640x422.jpg

Overview 1987 by Ching W. Tang Organic Solar cells Organic vs Silicon 100-500nm Electrophosphorescence Developed by chemical engineer Ching W. Tang in 1987. By applying the voltage in the opposite direction of what is used in organic solar cells the electrons and holes will recombine and create light. By changing this voltage, you obtain different colors. The reason that they are called OLEDs are that they use an organic substrate as opposed to regular leds which use silicon based substrate, Aluminum, or Galium Nitride to create light. This process of creating light is called Electrophosphorescence

Anode (transparent) - The anode removes electrons (adds electron "holes") when a current flows through the device. Conducting layer - This layer is made of organic plastic molecules that transport "holes" from the anode. One conducting polymer used in OLEDs is polyaniline. Emissive layer - This layer is made of organic plastic molecules (different ones from the conducting layer) that transport electrons from the cathode; this is where light is made. One polymer used in the emissive layer is polyfluorene. Cathode (may or may not be transparent depending on the type of OLED) - The cathode injects electrons when a current flows through the device.

Types Passive Matrix (PMOLED) Small screens High Power PMOLEDs have strips of cathode, organic layers and strips of anode. The anode strips are arranged perpendicular to the cathode strips. The intersections of the cathode and anode make up the pixels where light is emitted. Higher power than other oled devices. Still less power than led/lcd displays http://electronics.howstuffworks.com/oled3.htm

Active Matrix OLED AMOLED Fastest refresh rate Low Power Large Displays AMOLEDs have full layers of cathode, organic molecules and anode, but the anode layer overlays a thin film transistor (TFT) array that forms a matrix. The TFT array itself is the circuitry that determines which pixels get turned on to form an image. http://electronics.howstuffworks.com/oled3.htm

Transparent OLED 85% Transparent Passive or Active HUD’s When a transparent OLED display is turned on, it allows light to pass in both directions.  http://electronics.howstuffworks.com/oled4.htm

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Top-Emitting OLED Active Matrix Smart Cards Opaque or Reflective http://electronics.howstuffworks.com/oled4.htm Active Matrix Smart Cards Opaque or Reflective Security Chip on Credit Cards. Opaque or Reflective Substrate,

How does an LED/LCD display work? Backlight Polarizing Filters Etched Glass Electrodes Liquid Crystal Color Filters In order to understand why oled technology is better, we first need to understand how led/lcd displays work. There are 9 layers basic layers. The backlight (Galium Nitride blue leds) covered in a yellow coating to produce white light. The second layer is a horizontal polarizing light filter. The third layer is a transparent electrode. The fourth layer is horizontally etched glass The Fifth layer the liquid crystal itself. This is naturally orientated randomly. The sixth layer is vertically etched glass. By adding this layer it forces the liquid crystal layer to twist in a way we can manipulate. The seventh layer is a paired electrode. The eighth layer is a vertically polarizing filter. The final layer is composed of color filters RGB. When we turn on the electrodes it causes the liquid crystals to orientate themselves vertically. When they are orientated this way it means that the light coming out is horizontal. When that light reaches the vertical filter, no light will pass through making the RGB filters all be dark. https://www.youtube.com/watch?v=0B79dGR19Tg

Advantages Flexible Higher Contrast Wider Viewing Angles Faster refresh rate Brighter* Efficient Easy to produce Thin displays Due to the substrate being an organic material, it is flexible in its nature. They also have a much higher contrast when use in devices. True black is able to be achieved with OLEDs when they are used in large displays such as tvs. This is because led/lcd tvs currently use a shutter system to display an image. This makes a true black led/lcd tv difficult to show. In an oled tv it uses active matrix OLED system to control each individual oled. Making black darker than on led/lcd tvs. The desired color can also be created at a higher quality due to the lack of light that bled over. Oleds also have much wider viewing angles. At 30 degrees Lcd displays show 60% decrease in brightness and 50% decrease in contrast ratio. Oled displays brightness decreases by 1% while the contrast remains unchanged. This is because led displays work by blocking light. Going far off to the side you are also blocking some of the light which leads to a darker, more distorted image. Oleds appear normal up to 170 degree viewing angle. Oleds also have a faster refresh time of 1 micro second. This is up to 1,000 times faster than lcd/led displays. This leads to less motion blur on displays. Oled displays are also able to get very bright because of the organic substrate. This layer is able to be much thinner (0.35 mm) thick. To compare an led with an aluminum substrate can be around 4mm thick. Individual pixels can get brighter compared to led/lcd displays, however when the entire display is attempting to max out its brightness, led/lcd displays can get brighter. This is due to the light filtration system. If the light is not being filtered led/lcd screens can be slightly brighter. For example oled displays max out around 500 nits where led/lcd max out at around 800 nits. These displays are therefore more efficient, they are able to get just as bright as an led display would without as much power. When a display calls for a black part of the display, the corresponding pixels will be off. An led/lcd display never turns off, just simply blocks the light that goes there. However, while it generally uses less power, if a display is primarily white it will use more power. On average an oled display will use 60-80% of a regular display. Can go as low as 40% on a primarily black display. Oled displays are easier to produce because of the organic substrate. These can be made in large sheets like plastic. This avoids the need to grow and place the liquid crystals. Displays are substantially thinner than led/lcd displays. There is no backlight, or polarization filters. LG has made a new oled tv that is 2.5mm thin (4 credit cards). Thinnest led/lcd tv I found was 2.5 inches. http://pixelpainter.com/PVC/SmallHD-Jun2014/dp7-color-oled-lcd.jpg

http://www.provideocoalition.com/smallhd-dp7-pro-oled/

http://forum. hardware http://forum.hardware.fr/hfr/HardwarePeripheriques/Ecran/ecrans-widegamut-rec2020-sujet_61300_1.htm

https://www.youtube.com/embed/F7bGTaVehus

Disadvantages Lifetime (20-50,000) vs (60-100,000) hrs. Water Damage. Cost Quantum Dot TV’s The first disadvantage of oleds is their lifetime. Display lifetime is defined as the amount of time it takes to reach 50% of a device’s original brightness. The low lifetime is caused by breakdown of the organic material. Not protected by a glass layer so any moisture on the display will instantly cause damage. Sealing techniques are being investigated to maintain the flexible properties, yet protect the oleds. Oleds are theoretically cheaper to produce, however until oleds become the primary display technology they will remain the most expensive. Once they become mass produced, cost will decrease through scalability. Another disadvantage of Oled tv’s is that they are potentially replaced by quantum dot displays. These displays are still very early in the research phase, but they are very promising. These displays essentially change the backlight of current backlight of led/lcd displays. Opposed to the blue led layer with a yellow layer to create white light that is then filtered to create the RGB colors. The quantum dot will create the RGB colors, without the filtering process. https://en.wikipedia.org/wiki/OLED#/media/File:Oled_display_alterung.jpg

Future Applications HUD’s Clothing Windows Expandable Devices https://amazinglyweirds.files.wordpress.com/2015/01/samsung-folding-tablet-1.jpg

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Conclusion Oleds are an amazing new technology that have drastically increased image quality compared to the common led/lcd displays. Once this technology becomes cheaper to produce, it will become the most common display source.

Sources http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=1288078 http://ieeexplore.ieee.org/xpls/icp.jsp?arnumber=6338465 http://www.displaymate.com/LG_OLED_TV_ShootOut_1.htm http://www.pocket-lint.com/news/131200-11-reasons-why-your-next-tv-should-be-oled https://www.youtube.com/watch?v=PkACDOjaAtc http://electroiq.com/blog/2012/05/beyond-sapphire-led-substrates-gan-zno-sic-si/ http://www.oled-info.com/introduction http://gizmodo.com/why-is-oled-different-and-what-makes-it-so-great-1654102034 http://encyclopedia2.thefreedictionary.com/Organic+Glass https://en.wikipedia.org/wiki/OLED http://www.explainthatstuff.com/how-oleds-and-leps-work.html http://www.osram.com/osram_com/tools-and-services/services/faq/ledoled- lighting/index.jsp http://mashable.com/2012/10/03/oled-flexible/#NX7xVehNFuqq http://www.provideocoalition.com/smallhd-dp7-pro-oled/ http://www.konicaminolta.com/oled/products/

Sources Continued https://amazinglyweirds.files.wordpress.com/2015/01/samsung-folding-tablet-1.jpg http://electronics.howstuffworks.com/oled.htm http://www.provideocoalition.com/smallhd-dp7-pro-oled/ http://pixelpainter.com/PVC/SmallHD-Jun2014/dp7-color-oled-lcd.jpg https://www.youtube.com/watch?v=0B79dGR19Tg http://www.oled-a.org/images/pdfs/OLED%20Myths.pdf http://www.liantronics.com/News/2008101114573195948.html http://www.osram.com/osram_com/tools-and-services/services/faq/ledoled- lighting/index.jsp http://venturebeat.com/2016/01/05/lgs-new-oled-tv-is-as-thin-as-four-stacked-credit- cards/ http://www.cnet.com/news/led-lcd-vs-oled/ http://www.flatpanelshd.com/news.php?subaction=showfull&id=1446462482 http://www.techhive.com/article/3018446/smart-tv/oled-vs-led-theres-just-no- comparison.html

Key Points Organic Based Substrate Larger Contrast Electrophosphorescence Efficient Smaller Displays By 2004 Samsung, South Korea’s largest conglomerate, was the world's largest OLED manufacturer, producing 40% of the OLED displays made in the world,[106] and as of 2010 has a 98% share of the global AMOLED market Sony and LG BMW Interior and exterior lighting Mitsubishi Chermical Corp. Researched 30,000 hour Oled in 2004