Tag Archives: OLEDS

OLED Lighting in the Auto Industry

In recent years, a number of industries have started using Organic Light-Emitting Diodes (OLEDs) in diverse ways. The automotive industry, in particular, has seen a huge potential in OLEDs. For instance, very soon Audi will be coming up with OLED taillights. At present Audi has presented prototypes of the taillights. At the LOPEC Congress, Audi provides advanced insights into the needs of the automotive industry that the deployment of OLEDs will require to meet, and the future of automotive lighting.

So far, there have been plenty of developments. At LOPEC, Audi demonstrated prototypes of their OLED taillights, which they claim have reached production stage. However, using OLEDs in vehicles has always been a challenge, although OLED lighting installations and table lamps have been around for a while, and these are in use in museums, clubs, and restaurants.

Difficulties of Using OLED in Automobiles

Major hurdles OLEDs have to cross when in use in automobiles are they have to withstand humidity, heat, cold, UV radiation, and constant vibration. All these can reduce the life span of OLEDs drastically. Audi claims to have solved this problem by encapsulating their displays hermetically, which they claim will make the displays as stable as LEDs.

Why Use OLED in Place of LEDs?

Regular LEDs act as point sources of light, and it requires substantial development work for generating an even light from them. On the other hand, OLEDs are evenly radiating sources of light, and they naturally produce a uniform illumination. Moreover, their thickness is only about a millimeter, which makes OLEDs more suitable for automotive design.

Designers find OLED appearance is high quality, both when off and on. This is because it has a simple and clean surface. As design is an important aspect of the automotive industry, it makes OLEDs ideal for such use. Most automobile owners expect a certain lifestyle from their vehicles, apart from its functional use of transportation from point A to point B.

However, for use as turn signals and brake lights, the light intensity from OLEDs is not adequate, and will have to be increased. The automotive industry is also working on using flexible OLEDs. At present many are using glass-based OLEDs, but these are rigid, and using plastic foil substrates as the base for OLED is opening up a whole new world of opportunities for the designers.

Audi is expecting LOPEC will open up a huge bandwidth of business and research institutes for them. They expect to hold discussions with specialists using this breadth of activity, and to meet other OLED manufacturers and materials developers.

What the Future Holds?

In about a decade from now, the world will be witnessing innovations in vehicle lighting that most can only dream about today. As it is, a vehicle’s lighting system already functions as a form of communication—hazard lights, turn signals, brake lights, for example. In the future, driverless cars will need to interact with others on the road with even greater sophistication. One of the visions Audi has is of a three-dimensional OLED display extending the entire tail of the vehicle, on the panel of the body, and integrated OLED within the windshield.

Is there anything better than OLEDs?

Almost everyone uses a smartphone today and the displays are getting ever bigger. Larger screens are a pleasure to watch, but difficult to put inside a pocket. Therefore, Qibing Pei, a professor of materials science, is researching highly flexible and stretchable OLED displays that could allow a small elastic OLED smartphone to fit easily into one’s pocket and the screen could be expanded when viewing. That would certainly be a great help if successful, but in the meantime, there is something else, which is better than an OLED.

OLEDs require power and are expensive. Instead, carbon nanotube field emitters powering up a lighting panel are less expensive. They stimulate a phosphor in the panel to glow, much as the cathode ray tubes of the yesteryears did. The phosphor is brighter than the current OLEDs, consumes much less power compared to LEDs and is far less expensive than both of them are. Professor Norihiro Shimoi, a lead researcher at the Tohoku University in Japan is working on this technology. He uses light through a neutral density filter to illuminate nanotube field emitters to stimulate the phosphor.

Although the prototype in Professor Shimoi’s lab has yet to achieve 60-lumens per watt, it is similar in design to the flat version of the old cathode ray tube. Not expected for a commercial release before 2019, the nanotube prototype is like a lighting lamp, but with a power consumption of 1/100th of standard LED devices.

LEDs are all the rage today, owing their advantages over fluorescent and incandescent lighting because of the very low power consumption of LED based devices. With large-scale lighting, however, several LEDs have to be used together, which complicates the engineering and thermal design. On the other hand, the nanotube design is flexible enough to be formed into flat panels of any size.

Incandescent bulbs are the least efficient at a mere 15lumens per watt. In comparison, LEDs and fluorescent bulbs both produce about 100 lumens per watt. The difference is LEDs are point sources of light, whereas fluorescent bulbs spread their light over a much larger area. Organic cousins of LEDs, the OLEDs, produce about 40 lumens per watt but have the advantage of being incorporated into panels. According to Shimoi, simulating large phosphor-covered panels with electron field emitters made of carbon nanotubes will be more efficient. With their much lower power requirements, and producing 60 lumens per watt, these phosphors will potentially be brighter than OLEDs that produce only 40 lumens per watt.

Shimoi is currently working on reducing the energy loss by heat. The device employs highly crystallized carbon nanotubes and phosphors. These are coated with ITO particles. Shimoi is attempting to increase the electrical conductivity to reduce energy loss by heat. The process involves optimization of the crystallization of the carbon nanotubes along with the design of the lighting device.

Where typically, carbon nanotubes are made using semiconductor diode junctions, Shimoi has made them into excellent field emitters of electrons so that they can stimulate phosphors. Furthermore, production of these nanotubes does not require expensive clean rooms or high-temperature ovens. The nanotubes are single-walled and are grown by arcing.

Are OLEDS better than LEDS?

Chances are, you still own a TV that is bulky, has a picture tube and is kept on a table. Well, with advancing technology, TVs have become slimmer and lighter, can hang on the wall and do not have a bulky picture tube.

The new TVs have an LCD or a Liquid Crystal Display in place of the earlier picture tube. Now, unlike the picture tube, LCDs have no light of their own, and have to be lit with a backlight. Until recently, most LCD TVs were backlit with plasma discharge tubes or CCFL lamps.

The CCFL lamps are placed directly behind the LCD panel and this adds to the overall thickness of the TV. Another newer method of lighting up the LCD panel is with LEDs and these are placed all around the panel, just beneath the bezel of the screen. Some models, especially the larger sized TVs place the LEDs behind the panel.

According to the TV manufacturers, LED models provide a better contrast (difference between black and white parts of the picture). This is because LEDs can be turned off completely to render a complete black portion. With CCFLs, there was no turning off, and the blacks produced were not so deep.

With further advancement of technology, there is a new kid on the block, called OLED or Organic Light Emitting Diode. This is a thin layer of film made from an organic compound which emits light in response to an electric current. Unlike an LCD, an OLED screen needs no backlighting, making it the thinnest of all the screens for a TV; a screen, which can be rolled up.

Other advantage of OLEDs is its very high switching speed, which produces practically no blur when there is fast movement in the picture. Moreover, OLEDs can be switched off to produce black color, and there is no leakage of light from the neighboring OLEDs. This allows OLEDs produce the highest dynamic contrast among all the displays. Does that mean OLEDs are better than LEDs?

As the technology is relatively new, there are some primary difficulties that OLEDs face today. The first is OLEDs are still not as bright as LEDs are, and that makes them harder to see in sunlight or even in broad daylight. Additionally, with the present structure of the OLEDs, producing blue light is harder. This makes the images just passable.
Another issue with the OLEDs is their lifespan. At present, the OLED has the shortest lifespan among LED, LCD and other technologies commonly available on the market. The average lifespan of an OLED is only 14,000 hours, which means if you watch eight hours of TV every day, the OLED screen will last only five years.

Although OLEDs are good at displaying high contrast, they hog quite a bit of power when displaying all whites. Moreover, similar to the old cathode ray tubes or picture tubes, OLEDs are prone to burn-in, meaning if you let the picture remain static for long, a shadow of the picture remains on the screen.

The last disadvantage of OLEDs is their prohibitive cost.