LEDs

LEDs: Small miracles of light for a bright and sustainable future

Light-emitting diodes, known by the acronym LED for "Light Emitting Diode", are revolutionising the way we see and use light. A milestone in lighting technology, they are characterised by their remarkable energy efficiency, longevity, and versatility.

What are LEDs?

LEDs (Light Emitting Diodes) are electronic semiconductor devices that emit light when current flows in the forward direction. They belong to the category of active components because they can control the flow of current and convert electrical energy into light energy.

An LED is made of a semiconductor material, usually comprising gallium nitride (GaN) or gallium arsenide phosphide (GaAsP). Through the process of electroluminescence, LEDs produce light when electrons and holes recombine in the semiconductor layer. In the process, the energy of the electrons is released in the form of photons (light quanta).

What is the advantage of LEDs?

LEDs offer several advantages, including high energy efficiency, long life, low energy consumption and fast switch-on behaviour. They are available in a variety of colours, including red, green, blue, and white, and can be used for different applications, such as lighting, display and signalling, screens, automotive lighting, TV backlighting and more.

In addition, the development of power LEDs (high-power LEDs) also enables the use of LEDs in general lighting, as they can produce enough brightness to replace conventional incandescent lamps. LED technology has made significant progress in recent years and is increasingly used in various applications due to its efficiency and versatility.

How does a light-emitting diode work?

A light-emitting diode (LED) belongs to the group of III/V semiconductor devices. This means that it consists of materials that belong to the third and fifth groups of the periodic table. The LED consists of a semiconductor crystal, also called an LED chip, which is the central element. The semiconductor crystal generates light through physical processes.

The functioning of a light-emitting diode (LED) is based on the principle of recombination of electrons and electron holes. The semiconductor crystal of the LED consists of an n-doped layer with an excess of electrons and a p-doped layer with electron holes.

When a voltage is applied in the flow direction of the LED, the excess electrons from the n-doped layer migrate to the p-doped layer. There they meet the electron holes and recombination occurs, in which electrons and electron holes combine. This releases energy in the form of light flashes, i.e. photons.

The LED chip conducts these light flashes to the outside, whereby the inner sides of the reflector well amplify the emerging light and increase the light yield. This process of recombination and light emission continues if the voltage source supplies electrons. In addition to light emission, a small amount of waste heat is also produced during recombination.

How are the bright colours of LEDs created?

The blaze of colour we see in light-emitting diodes (LEDs for short) comes from science. Different semiconductor materials produce different colours of light when excited to glow by electricity. Wondering which materials are responsible for which colours? Here is a brief overview:

1. gallium arsenide (GaAs): from red to infrared.

2. gallium phosphide (GaP): red and yellow

3. gallium nitride (GaN): from green to blue and ultraviolet

4. indium gallium nitride (InGaN): blue, green, white

5. aluminium gallium indium phosphide (AlGaInP): red, orange, and yellow

6. aluminium gallium nitride (AlGaN): ultraviolet

The colour of an individual LED depends on the exact composition of the semiconductor material and is controlled by special doping processes and structuring techniques during manufacture. Mixing different materials creates the colourful RGB LEDs (red, green, blue), which can produce a variety of colours by adjusting the intensity of the individual colours.

It should be noted here that other factors such as the internal phosphor layer (for white LEDs) or the use of phosphor converters (for coloured LEDs) also play a role. They can influence the spectrum of the light produced and enable an even wider range of colours.

Get creative: DIY projects with LEDs

LEDs are not only technologically fascinating, but also super useful and versatile for all your DIY projects. Let's look at some examples:

Lighting: you've probably seen LEDs in DIY lighting projects before. Be it to install LED strips for atmospheric indirect lighting in your rooms, in cabinets, on shelves or as backlighting for your TV.

Decoration: LEDs are the secret weapon for DIY decoration projects. For example, you can use them for homemade fairy lights, glowing accents in glass bottles or to illuminate artwork and wall decorations.

Arduino projects: LEDs are often the shining star in Arduino projects. They help you create visual effects and serve as indicators and signals in your DIY electronics projects.

Costumes and props: LEDs can be used to create glowing effects in your DIY costumes and props. Embed them in clothing, masks, hats or accessories and you're sure to stand out!

Jewellery and accessories: Built-in LEDs give your DIY jewellery and accessories a

What is the difference between a diode and an LED?

Both - diode and LED - are important components in electronics, but they have different tasks and functions.

A diode is an electronic component that allows current to pass in one direction and blocks it in the other. It essentially acts as a kind of electronic check valve. This feature is particularly useful in many electronic circuits where it is important to control the direction of current to prevent damage to other components or to generate direct current (DC) from alternating current (AC).

A light emitting diode, or LED, is a special type of diode that produces light when electric current flows through it. It has the same unidirectional properties as a normal diode, i.e. it only allows current to flow in one direction, but has the additional property of emitting light when current flows through it. This light can have different colours depending on the semiconductor material used in the LED.

In summary, all LEDs are diodes because they only allow current to flow in one direction, but not all diodes are LEDs because not all diodes can emit light. LEDs are specifically designed to emit visible light, which distinguishes them from regular diodes.

Notes on the use of LEDs that you should observe:

Voltage and current conditions:

LEDs are semiconductors and therefore sensitive to voltage and current conditions. Exceeding the maximum permissible voltage or current can damage the LED or shorten its life. Therefore, it is important to use a suitable series resistor or constant current driver to ensure the correct voltage and current.

Heat dissipation:

Even though LEDs are more efficient and generate less heat than conventional incandescent lamps, they can still become warm during continuous operation. Adequate cooling is important, especially with high-power LEDs, to prevent overheating and extend the life of the LED.

Dimmability:

Not all LEDs are dimmable. If you want to dim an LED, you must make sure that both the LED and the dimmer are suitable for this. Otherwise, flickering or premature failure of the LED may result.

Correct disposal:

LEDs contain electronic components and sometimes substances that can be harmful to the environment. Therefore, they should not be disposed of in regular household waste. Many countries offer special recycling programmes for LEDs and other electronic products.

FAQs on light-emitting diodes (LEDs):

What does the abbreviation "LED" mean?

LED stands for "light emitting diode". These special diodes produce light when an electric current flows through them.

Are LEDs environmentally friendly?

Yes, LEDs are generally considered to be more environmentally friendly than many other types of lighting. They use less energy, which results in lower CO2 emissions, and they have a longer lifespan, which means they are replaced less often, creating less waste. However, it is important to dispose of LEDs properly at the end of their life, as they may contain materials that can be harmful to the environment and human health.

Can LEDs light up in all colours?

Yes, LEDs can glow in a variety of colours depending on the semiconductor material used. Red, green, blue, yellow, and white are common colours, and different hues and brightnesses can also be produced. In addition, there are RGB LEDs (red, green, blue) that can produce a very wide range of colours by mixing the three colours.

Why do LEDs not get hot?

Unlike conventional incandescent lamps, which convert most of the energy they consume into heat, LEDs convert most of the energy directly into light. Therefore, they generate less heat. Nevertheless, high-power LEDs can get hot when used continuously. However, the heat is usually dissipated by a heat sink on the LED chip, so the lamp itself becomes only moderately warm.

Can I dim LEDs?

Yes, many LEDs are dimmable, but not all. Whether an LED is dimmable or not depends on its specific design and the driver used to regulate the current. With dimmable LEDs, it is important to use a suitable dimmer, as not all dimmers are compatible with LEDs. This should be stated in the product information of the LED. It is always advisable to follow the manufacturer's instructions to ensure that the desired LED and the dimmer used are compatible.