How OLEDs Work?

In the 1980's all were fond of TV’s no matter what color picture it gave. Earlier TVs were powered by CRT’s - Cathode Ray Tubes. These TV’s were too heavy to lift. As time is passing, new technologies are emerging. After CRTs, LCD screens were introduced and now the OLED screen both are light in weight. But OLED is best from all.

Let’s See What is OLED?

First understand What is LED?

LED’’s are small colorful indicator lights that you see in every electronic device these days. They are light in weight, energy efficient and more reliable than CRT’s.

OLED is an advanced version of LED, where light is emitted by organic particles. Do not get confused with the word “Organic”. This word is not related to nature, it is related to chemistry here. In 12th class or before that everyone in chemistry must have read this word Organic that means particles that are based around carbon atoms.

OLED, the organic light emitting diodes technologies provides thinner brighter and more colourful TV sets. They give beautiful picturisation of curved screens as well.

Now the question is How OLEDs Work?

Unlike conventional diodes, LED; OLED also works in the same manner. The only difference is that instead of using n type and p type prototypes in OLED organic molecules are used to produce their electrons and holes.

A simple Organic Light Emitting Diode is made of six different layers. First the OLED is protected with protective glass or plastic.

The top one is Seal - This layer is made of organic molecules or polymers.

The bottom layer is called Substrate - This layer is made of clear plastic, glass or foil.

In between these two layers are cathode and anode layers.

The Anode - is transparent. It removes electrons and adds electron Holes when current flows through the device.

The Cathode - This layer may or may not be transparent depending on the type of Organic Light Emitting Diode. It injects electrons when current flows through a device.

In between cathode and anode there are two layers.

The emissive - The layer next to the cathode from where the light is immersed. This layer is made up of organic plastic molecules, one different from conductive layers.

The conductive - The layer next to the anode. This layer is made up of organic plastic molecules that transfers holes from the anode.

Note: redesign this image, as I have just copied it from other website as an example to show you.

How actually an OLED emits light?

Attach a voltage across anode and cathode terminal.
Once the voltage passes across the anode and cathode, the cathode receives electrons from the power source and the anode starts losing them. Thus electricity starts to flow.
Now added electrons are becoming negatively charged similar to N-layer in a junction diode. On the other hand the conductive layer is becoming positively charged similar to the P-type layer.
At the boundary between the emissive and conductive layer the electrons find the electron holes giving up energy in the form of a photon of light.
This is how OLED emits light
Next the color of the light depends on the type of organic molecule in the emissive layer.

Last but not the least, the intensity of the light depends on the amount of electrical current applied. The more the current the brighter is the light.

Benefits of OLED Displays

Lower Power Consumption
No backlight required
These are flexible and lighter than traditional LCDs
They emit real colors
OLED temperature displays can operate in a broader temperature range.

Types of OLED

There are different types of OLED.

Transparent OLED - This OLED uses transparent components like substrate, anode and cathode. When turned on it’s OLED display can be either used as an active or passive matrix design.

Top Emitting OLED - These OLED’s have either opaque or reflective substrates They are best used for active matrix designs..

Foldable OLED - As the name suggests foldable OLEDs are made of flexible metallic foils or plastics. Foldable OLEDs are durable and very light in weight.

White OLED - White OLED emits white light i.e more brighter and energy efficient. In future these lights can replace fluorescent lights used in homes and buildings.