Do you know what is OLED? Do you use it??
Have ever this question appeared in your mind. If yes then great else you should always be curious to know how new tech that govern your entertainment functions.
Today, there are a large number of displays that are manufactured using OLED. The large scale use of OLED has some reason.
Why it is being used in a variety of products? This post answers such similar questions.
The first practical OLED
- Ching W. Tang and Steven Van Slyke, two American physical chemists at Eastman Kodak built the first practical OLED device in 1987. This device was two-layered in structure namely, a hole transporting and an electron transporting layers such that the recombination and light emission occurs in the middle of the organic layer.
Therefore, resulting in a reduction in operating voltage and improvements.
What is OLED?
OLED is a type of display which is now found in many fitness trackers, smartwatches, T.Vs, etc. From CRT to OLED and the progress is going on, display tech has come a long way. OLED stands for ‘Organic LED’.
Yeah, LED here is our ‘Light Emitting Diode’ which we all have used in our life.
So, what ‘Organic’ stuff this LED has?
Don’t worry I’ll soon catch up with this discussion but before that, we will just revise what an LED is?
So, an LED is a display technology which uses minute solid-state devices. Moreover, these devices generate light using electron mobility through the semiconductor.
Therefore, they have nice illumination but this comes with a cost. Though these are smaller in size and thinner but not thin enough to drive each and every pixel.
This is the reason why we do not find any display with sole LED technology.
The screens that we call LED is actually LCD with LED backlight.
Now, OLED also produces light when electricity is applied so you might think both are the same. Yes, their fundamentals are same but OLED as its name suggests making use of organic material [Carbon]. This enables engineers to design even thinner, simpler and efficient display panels.
So, do the OLED display to use OLED as a backlight tool?
The answer is NO, these are so small that they can illuminate each pixel. This is the reason why OLED displays are much better than LCDs and LEDs.
Why OLED is Better Than LCD?
- Superior image Quality.
- Ultra-thin, flexible, foldable and even rollable & transparent [Check out LG’s discoveries]
- OLED’s can survive broader temperature ranges making them durable.
- Even at this level, OLED’s have a simpler design.
- Green Technology
With all these qualities you might be wondering that OLED’s are perfect. Sorry to disappoint you but OLED’s do have drawbacks. Manufacturing OLED is currently expensive.
We can expect the production price to drop in the near future as the OLED’s have a simple design.
Moreover, they have a short lifetime. As they are organic, they tend to degenerate or deteriorate after long hours of usage until now. But due to the advancement in technology, today we can use these OLED gadgets without worrying about its life as they now have a better & sufficient life.
Types Of OLEDs
There are many types of OLED that you can find today.
Passive Matrix OLED also called as the PMOLED is the design type which consumes the most power. In the event of PMOLEDs, strips of cathode and anode are used. These strips are placed perpendicular to each other having the organic material in the middle.
Here the intersection of the cathode and the anode is considered to be the pixel which emits light.
For PMOLED we use an external circuitry system which drives these pixels.
- They are easy to design and manufacture
- Very much efficient
These consume more power than any other type
Furthermore, the reason for PMOLED to consume so much power is its driving force itself, external circuitry. The external circuitry demands power in order to light the pixel. But still, PMOLED used less power as compared to the LCDs.
- Best to display text and icons
- Used in devices with small screen
Active Matrix OLED also was known as the AMOLED is one of the most used OLED display types. Moreover, these are much better than the PMOLED, we will soon see the reason for this.
AMOLEDs have complete layers of cathode, anode and the organic molecules. They are as follows –
- Upper Layer – Cathode
- Middle Layer – Organic Molecules
- Bottom Layer – Anode
All these layers overlap each other. Most importantly, the anode also has a layer which it overlaps, a thin film of transistor [TFT]. This film is the one that distinguishes the AMOLEDs from the PMOLEDs.
This layer is the one which determines which pixel should get involved in forming a particular image.
Advantages of AMOLED –
- Consume Less Energy
- Better refresh rates
- Better video quality
- Larger screens and electronic boards
- Great choice for computer monitors.
The Transparent OLED is a type of OLED that can be manufactured by using any of the above types –
This type OLEDs have the same materials such as the cathode, anode and the substrate. But these materials should be transparent. The structure of the panel is as follows –
- Emissive Layer
- Conductive Layer
Surprisingly, the display can be transparent up to 85% of the substrate when the display is switched off. The factor that makes this display transparent is the collective transparent nature of the individual materials.
Therefore, when we switch off the display, it allows light to travel in both the directions.
Top-Emitting OLEDs have a design similar to that of the Transparent OLED. But the substrate used here is not transparent instead they are reflective or opaque in nature. The Active-Matrix design best suites for achieving such a display.
It might seem weird that there exists something known as a foldable display. Moreover, if you are unaware of a product having this then you should check out the above video, they have Transparent TV too. The basic components used are the same – cathode, anode and the substrate.
Furthermore, here the substrate that we use are flexible in nature then only the product can be foldable. Therefore, substrate usually comprises of metallic foils which are flexible and plastics.
Even though the substrate is foil or plastic, it is durable.
Areas of use –
- In display devices [must in smartphones] to reduce the probability of damage to the screen.
- Due to thin & foldable nature, it can be integrated with clothing etc to add smart features.
OLEDs do have the property of emitting white light. Therefore, White OLED is a display that emits white light. Moreover, these lights are brighter and energy efficient than the Fluorescent lights.
Development in this technology will soon replace the use of fluorescent lights.
- The emitted light has high uniformity
- Less energy consumption
- Has true-colour qualities
- Large scale production is possible.
Gadgets in which you can find OLED in action –
- Lamps/ Lightings
Now, How OLEDs Work??
The following are the core components of the OLED technology –
- Organic Layers
- Conducting Layer
- Emission Layer
The major part of the OLED manufacturing process is the application of the organic layer to the substrate.
There are a total of three ways to achieve the same –
- Vacuum deposition or Vacuum Thermal Evaporation [VTE]
- Organic vapour phase deposition
- Inkjet printing
You can check this post by HowStuffWorks, they have given detailed information on the components and the methods.
Now, we will learn how illuminance practically produces. OLEDs emit light in a similar way as the LEDs do, through the process called Electrophosphorescence.
The battery of the device using OLED applies a voltage across the OLED. This generates an electric current that flows till the anode through the cathode and the organic layer.
The cathode supplies electron to the emissive layer of the organic substrate. Moreover, the anode accepts attracts the electron from the conductive layer of the organic substrate.
Therefore, creating holes in the conductive layer.
The substrate has the emission and the conductive layer. Actual magic happens here, the region between both these layers. This is the region where the electrons meet the holes which result in their union releasing energy in the form of light [photons].
Manufacturers produce vivid light in the visible range by stacking several types of organic films on the OLED.
Thanks for bearing with me throughout this post. I wish you enjoyed a lot from this article and those who were known to OLED learned a lot.
Hence, in summary, OLED is an emerging technology which has many applications.
Moreover, other areas of use cases are also under research and will soon be explored.
So, share this piece of information to your loved ones and have a delightful day.