How do white LED lights work?

Phosphor-converted LEDs generate white light by blending light of various colors. In one commercial design (left), light from a blue-emitting LED excites a yellow phosphor. Blue and yellow combine to make white light. White-light-emitting LEDs are an incredibly promising lighting technology.

How can we obtain white light from a semiconductor LED?

LEDs do not directly produce white light. There are two ways in which white light is produced from LEDs as below: Using a blue LED with a phosphor coating to convert blue light to white light by a process called fluorescence. Combining red, blue and green LEDs to produce white light.

What semiconductors are used in LEDs?

The main semiconductor materials used to manufacture LEDs are:

• Indium gallium nitride (InGaN): blue, green and ultraviolet high-brightness LEDs.
• Aluminum gallium indium phosphide (AlGaInP): yellow, orange and red high-brightness LEDs.
• Aluminum gallium arsenide (AlGaAs): red and infrared LEDs.

How do LED lights work chemistry?

When a current is applied to the LED, the electrons in the n-type layer and the electron ‘holes’ in the p-type layer are driven to an active layer between the two. When the electrons and electron ‘holes’ combine, energy is released, and this is seen as visible light.

What does white LED lights mean?

“Cool” white LEDs emit more blue, and the radiation is classified as hotter, although again, humans have an alternative perception that determines the light is cooler.

What is bright white LED?

Bright white (4,000 to 5,000 Kelvin) is between white and blue tones. With a less cozy and more energetic feel, bulbs with this color range are best for work spaces (such as a home office or garage) and kitchens with chrome fixtures. Daylight (5,000 to 6,500 Kelvin) has a more bluish tone.

How does the white light produce in the tube?

Why a Tube Light produces White Light? The electricity causes tiny particles, called electrons, to travel at high speeds between the poles. Since the human eye is unable to see this radiation, the glass tube is coated with a fluorescent material which changes it into white light.

Which semiconductor is suitable for LED and why?

Answer: The particular semiconductors used for LED manufacture are gallium arsenide (GaAs),gallium phosphide (GaP), or gallium arsenide phosphide (GaAsP). The different semiconductor materials (called substrates) and different impurities result in different colors of light from the LED.

How are LEDs manufactured?

The semiconductor material is “grown” in a high temperature, high pressure chamber. Elements such as gallium, arsenic, and/or phosphor are purified and mixed together in the chamber, which then liquefies into a concentrated solution. Once the elements are mixed, a rod is placed in the solution and slowly pulled out.

Which semiconductors are preferred to make LED and why?

Explanation: Semi-Conductors with a heavily doped forward-biased p-n junction having a band-gap of Energy 1.5eV are the most appropriate choices to make the LED.

Is LED light white light?

Unlike incandescent lamps, LEDs are not inherently white light sources. Instead, LEDs emit nearly monochromatic light, making them highly efficient for colored light applications such as traffic lights and exit signs. However, to be used as a general light source, white light is needed.

What are the uses of white LEDs?

The recent development of white LEDs is what has brought it into the public eye as a replacement for other white light sources. Common uses: indication lights on devices, small and large lamps, traffic lights, large video screens, signs, street lighting (although this is still not widespread) Large LED array designed for use as a street lamp.

How is the colour of light emitted from a semiconductor produced?

Pure gallium arsenide releases energy in the infra read portion of the spectrum. To bring the light emission into the visible red end of the spectrum aluminium is added to the semiconductor to give aluminium gallium arsenide (AlGaAs). Phosphorus can also be added to give red light. For other colours other materials are used.

What are the different types of LED light emitting diodes?

There are still different subtypes of light emitting diodes. SMD LED’s and COB LED’s are mainly used for LED illuminants and luminaires. The abbreviation SMD stands for surface mounted device. SMD LED’s can be mounted directly on the printed circuit board in the light source.

What are phosphors in led’s?

Phosphors are used to help filter the light output of the LED. They create a more pure “harsh” color. Engineers had to figure out how to control the angle the light escapes the semiconductor, this “light cone” is very narrow.