What is OLED Display? Types, Working Principles & More

What is OLED Display?

OLED or Organic Light Emitting Diode refers to a display technology. Instead of using the traditional silicon or gallium materials to make the LEDs, OLEDs use carbon emitting organic layers. It follows the principle of electroluminescence.

Technically, OLED refers to that particular display technology in which a flow of current between the cathode and an anode illuminates the emissive layer made up of organic molecules placed between them.

KEY TAKEAWAYS

• The OLED displays come with several unique features and benefits such as higher resolution, better color, faster response time, better contrast ratios and more. These displays are thinner and more flexible and therefore can even be folded.
• The lifespan of this display is variable and depends on the use cases and not on any mechanical components. Usually, on moderate use, an OLED monitor can last anywhere between 8 to 10 years.
• The most common issue of the OLED displays is screen burn-in and the use of the organic material, both of which can degrade its performance and life.
• This display functions without a backlight following the principle of electroluminescence and therefore consumes less power and displays better blacks.
• There are basically two types of OLED displays namely PMOLED and AMOLED, apart from a few others, and both are much better in performance when compared to traditional LED or LCD displays.

Understanding OLED Display

OLED displays are based on a specific screen technology owned by Universal Display Corporation.

Actually, OLED refers to a solid state device made up of a thin semiconductor that is based on carbon or organic material.

This semiconductor layer emits light when electricity is applied on it from the contiguous electrodes.

One of these electrodes must be transparent in order to allow light escape from the device.

The amount of this electricity applied by the electrodes in the OLED display basically controls the intensity of the light that is emitted.

On the other hand, the color of the light is determined by the kind of emissive material that is used.

In order to create white light, typically red, green, and blue emitters are used by most of the OLED devices and these are arranged in a number of configurations.  For example it can be as follows:

• A simplest and low cost single stack OLED
• A more complex stacked OLED that increases the brightness without increasing the current density and
• A striped OLED pattern in RGB or blue and yellow that allows tuning the color.

Typically, the OLED displays do not need filters and backlights like the LCDs need and therefore are considered to be much more energy efficient. It is also easier to make much thinner than the LCD screens and are, in fact, flexible and foldable!

The OLEDs used in the displays are specially made with an inkjet spraying process.

The substrate material is created in this process following a special dispersion technique in order to coat it with an even layer of conductive molecules.

The same process is followed to add another layer to the matrix but this consists of emissive molecules. If necessary, further layers can be added.

All these are organic layers and are complete with a cathode and an anode inserted between the sandwiched organic layers to make it a self-contained circuit.

After that, the ultimate seal of plastic or glass is applied to finish making an OLED display.

The small OLED displays can display as many as 65k colors while the larger ones can produce 262k colors.

All these displays come with a high contrast rate and the visible portion of it contains 96 x 64 RGB pixels, each of which is made up of red, green and blue OLEDs.

16-bits of resolution can be set in each of these pixels to offer a large range of colors with very high contrast which makes the black look truly black. This is because, as said earlier, in the OLED displays there are no backlights.

You can connect an OLED monitor by using the most common cables such as VGA which carries only analog signals, DVI which carries both digital and analog signals, DisplayPort which delivers both audio and video signals, and HDMI for high-quality audio and video signals.

Types of OLED

Ideally, there are two major categories in which the OLED displays can be grouped namely, the Passive Matrix Organic Light Emitting Diode Displays or PMOLED and the Active Matrix Organic Light Emitting Diode displays or AMOLED.

The main difference between these two types of OLED displays lies in the driving electronics. For one it is the Passive matrix and for the other it is the Active Matrix.

The PMOLED displays typically use a simpler control scheme for every row or line in the display one after the other.

However, each of these lines is basically off most of the time because there is no storage capacitor. Therefore, additional voltage is needed to make them brighter.

However, PMOLEDs are cheaper and easier to produce but are not long lasting or efficient due to the materials used in making them. It is due to the high voltage requirements.

These displays are also limited in size and resolution, also due to their high voltage requirements.

This is why these are used in smaller devices to display small icons and character data.

The AMOLED displays, on the other hand, are typically driven by a Thin Film Transistor or TFT which has a storage capacitor to control the states of the line pixels. This enables creating large size AMOLED displays with higher resolutions.

Nowadays, with the advancement in the OLED screen technology, you will also get Polymer Light Emitting Diodes or PLEDs and Quantum Dot OLEDs or QD-OLED.

The QD-OLEDs however use quantum dots that are nano-crystals that emit lights along with conventional OLED material.

OLED Working Principles

The working process of the OLED displays is basically dependent on the functioning of the six separate layers, two of which have organic properties in them.

The steps involved in this process are:

• The particular organic layers produce light when current is passed through them
• The light then passes through the color refiner and
• The final image is produced on the screen.

Simple as it may sound, the process is quite complex and can be explained in two simple steps as follows:

• The electrical charge applied on the array of layers creates a flow of electrons from the cathode to the anode.
• The electrons are drawn from the conductive layer by the anode and the electrons flowing from the cathode are received by the emissive layer.

This continuous flow of shifting electrons from cathode to anode creates electro fluorescence.

This specific working process makes the traditional LEDs backlight redundant making them more energy efficient which helps in the forming of very thin, transparent and flexible OLEDs.

Typically, the OLED displays follow the same working process as the LED displays but in a slightly different way since it can produce its own light and therefore do not need backlights like the LEDs do.

Advantages of OLED

One of the most significant advantages offered by the OLED displays is its better contrast along with a higher refresh rate which makes them much more attractive than any other type of display technology.

Some other significant advantages that you can enjoy while using an OLED display are:

• These are more power efficient displays simply because they do not need any backlights due to the organic material used in the LEDs
• Since they consume less energy, they in turn produces much less heat as well which enhances the battery life of those devices that come with an OLED display
• The images displayed on an OLED display is much more vivid and accurate in colors and are more saturated
• It comes with highest contrast ratio which helps it to display images with deepest and perfect black
• These displays offer a much wider viewing angle as compared to other displays of up to 180 degrees
• The form factor is extremely thin and flexible so much that these screens are foldable
• These specific displays come with super fast response time, often in microseconds, which allows delivering high quality, fast, seamless and crisp motion picture even in 3D applications
• The displays can be configured as larger area for more diffused light sources so that the soft light is directly visible
• It eliminates the need for diffusers, shades, louvers, lenses or parabolic shells because the diffuse light from OLEDs allows using them extremely close to the task surface so that it does not create any glare for the user
• The OLED displays use less total light in order to attain and maintain the required luminance levels.
• The thin form factor of the OLED displays can be attached to any surface such as walls and ceilings which increases the eye appeal and
• These specific displays can control the pixels individually according to the requirement to produce accurate colors and can even be turned off completely to produce perfect blacks.

OLED vs LED

• The OLED displays consume much less power in comparison to the LED displays since they do not have backlights
• The picture quality offered by the OLED displays is much better in comparison to the LED displays.
• The LED displays are much brighter than the OLED displays due to the presence of backlights
• The response time of the OLED displays is much faster as compared with the response time of the LED displays
• The OLED displays are known for their high intensity when compared with the LED displays
• The OLED displays have self-illuminating capabilities but the LED displays need backlights to start the process
• The viewing angle offered by the OLED displays is wider in comparison to the viewing angle of the LED screens
• Images on a LED display is best viewed from the center whereas the images on an OLED display looks good from any sides
• The LED displays have a point light source but in comparison the OLED displays function on a surface light source with diffused light
• The OLED displays generate less heat due to less consumption of energy and it is also easy to dissipate heat from them in comparison to the LED displays
• The images on an OLED display usually have more color uniformity and volume and are also free from dark patches than the images on the LED displays
• The faster refresh rate of the OLED displays than the LED displays make the picture sharper and more seamless
• The OLED displays uses organic light emitting diodes but the LED displays use simple light emitting diodes and
• The OLED displays are known to suffer from screen burn-ins which is not as big an issue with the LED displays.

OLED vs LCD

• An OLED screen displays much better and clearer images with vivid colors as compared to the LCD panels
• It comes with higher contrast ratio to produce perfect blacks in comparison to the LCD screens
• The OED display offers much wider viewing angles than an LCD panel
• The refresh rate of the OLED display is much faster than the LCD screens
• The thin form factor of the OLEDs makes it more flexible than the LCD screens and can even be folded
• The LCD screens are not as power efficient as the OLED displays
• The OLED displays do not need backlights to create light like the LCD screens which makes them more power efficient
• Since the OLED displays consume less power they also produce less heat in comparison to the LCD screens
• The diodes in the OLED displays can be turned off completely to produce accurate blacks but the backlight of LCD screens behind the device do not offer such benefit
• OLED displays emit less blue light in comparison to the LCD screens because there is no backlight
• Due to the presence of backlights in LCDs these displays offer more brightness than OLED displays
• The OLED displays support HDR much better than the LCD screens
• OLED displays excel in terms of uniformity and consistency in comparison to the LCDs which is known for leaking lights from the edges
• The LCDs however do not suffer from screen burn-in or image ghosting as much as the OLED displays do and
• The OLED displays suffer from color issues such as pop, vibrancy and volume more than the LCDs

Does LCD or OLED Last Longer?

The lifespan of a display entirely depends on the hours of use and the advantages offered by each are highly dependent on the use cases as well. Moreover, there is not much data available right now to determine a clear winner among OLED displays and LCD panels.

Ideally, on whatever data and research results are available, the LCD screens have been on the market for a much longer time than the OLED displays which means that there is more data available to support their longevity than the OLED screens.

Based on those reports, it can be said that the LCD panels can perform for about 60,000 hours which is equivalent to around 2,500 days of operation. Ideally, this refers to about 7 years of steady performance in most of the cases.

On the other hand, an OLED display producing 8,300 nits is usually rated for about 40,000 hours when used at 25% brightness or 2,075 nits. However, when it is used at its full capacity, it may come down to 10,000 hours.

The modern OLED displays are expected to perform steadily for about 100,000 hours, which is about 10 hours of usage every day for 10 years but it should be maintained properly.

How Long Do OLED Panels Last?

It can be safely said that the lifespan of the OLED displays depend on how it is used and for how long a day.

If it is used to display static images for a long period of time than displaying constantly moving and dynamic images it may not last long.

Everything basically depends on how many hours you use it. If you watch it for about 6 hours a day, then it can last up to 22 years!

However, there are different claims from different manufacturers of OLED displays.

Some say that their product will last for about 30,000 hours without defects which is equivalent to 27 years but when it is used for 3 hours a day.

However, there are a few specific news blogs that claim that OLED panels from LG may last for as much as 100000 hours.

This is approximately 10 years of usage but OLED displays are also known for their susceptibility to burn-ins.

Questions & Answers:

Conclusion

After going through this article now you know that the OLED displays are fantastic innovative technology that has taken the viewing experience to the next level.

Though it has some significant downsides, the advantages offered by it outweigh them. However, the life expectancy can be varied depending on the usage.