Here’s Everything You Need To Know About Electroluminescence

What Is Electroluminescence?

Discovered by Captain Henry Joseph Round in 1907, electroluminescence is the emission of light by a material when subjected to an electric current or a strong electric field. 

Electroluminescence is a result of the movement of electrons in a material. When an electric current is applied, electrons are forced to move through the material. Electroluminescence is a very efficient way to produce light. Unlike incandescent lamps, which produce light by heating a filament, electroluminescent devices do not waste energy as heat. This makes them a more energy-efficient lighting source.

How Does Electroluminescence Work?

Electroluminescence works by exciting electrons in a material with an electric field, causing them to emit light particles (photons) as they return to their normal state. Here is a breakdown of the process:

• Electric Current Or Field: The key ingredient is applying an electric current or a strong electric field to the material. This creates an energetic environment for the electrons within the material.
• Electron Excitation: The electric field pushes the material’s electrons to higher energy levels. Imagine them getting bumped up to a more energetic state.
• Relaxation And Photon Emission: Those excited electrons don’t stay hyperactive forever. They tend to relax back down to their normal energy levels. When they do, they release the extra energy they are holding in the form of a light particle, a photon.
• Light Colour: The specific colour of light emitted depends on the energy gap between the excited and relaxed states of the electrons. Bigger gaps produce higher energy photons, translating to bluer or violet light. Conversely, smaller gaps emit lower energy photons, appearing as red or orange light.

There are two main types of electroluminescence:

• Intrinsic: In this case, the material itself has properties that allow its electrons to be excited by the electric field, and no external injection of charges is needed. 
• Charge Injection: This is more common. Here, an external electric current injects electrons into the material, causing them to get bumped to higher energy levels and releasing light as they relax. This is the principle behind LEDs (Light Emitting Diodes) and OLEDs (Organic Light Emitting Diodes).

What Are The Applications Of Electroluminescence In Semiconductors?

Semiconductors are the rockstars of electroluminescence, playing a starring role in many of the applications we rely on every day. Here are some key applications of electroluminescence in semiconductors:

• Light-Emitting Diodes (LEDs): LEDs use electroluminescence in specially designed p-n junctions to create light. By controlling the materials used and the way the junction is formed, engineers can produce LEDs that emit various colours with high efficiency. LEDs are now ubiquitous, used in everything from traffic lights and car headlights to smartphone displays and TVs.
• Organic Light-Emitting Diodes (OLEDs): OLEDs are another major application. They utilise thin films of organic semiconductors that emit light when subjected to an electric current. OLEDs are known for their excellent image quality, high contrast, and thin profile. They are found in high-end smartphones, tablets, and even some televisions.
• LCD Backlighting: Electroluminescent panels made from semiconductors are often used to backlight Liquid Crystal Displays (LCDs). These panels provide a uniform and energy-efficient way to illuminate the LCD screen, making the text and images clear and visible. They are commonly found in laptops, calculators, and other portable devices.
• Solid-State Lighting: Researchers are actively exploring using electroluminescent semiconductors for general solid-state lighting applications. These light sources have the potential to be much more energy-efficient and have a longer lifespan compared to traditional incandescent bulbs.
• Optical Sensors: Electroluminescence in semiconductors can also be used in certain optical sensors. By analysing the light emitted or absorbed by the material under various conditions, these sensors can detect things like presence, pressure, or even gas composition.