A Clear LED emitting different coloured light?

  • Context: Undergrad 
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Discussion Overview

The discussion centers on how a clear LED emits different colors of light, focusing on the underlying principles of LED operation, including the role of semiconductor materials and the control of power and current.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant suggests that the chip controlling the LED adjusts power to influence electron energy levels, thereby affecting emitted colors.
  • Another participant clarifies that the color of an LED is determined by the properties of the semiconductor chip rather than the plastic cover.
  • A participant inquires about the specific properties that affect color, seeking a fundamental understanding of LED operation.
  • It is proposed that the band gap of the semiconductor material is a key property determining color, with multi-color LEDs containing several different materials, each producing a fixed color whose brightness can be varied by current control.
  • A comparison is made to computer and TV displays, where varying brightness of red, green, and blue components creates a full spectrum of colors.
  • A reference is provided for further reading on semiconductor materials related to LED color determination.

Areas of Agreement / Disagreement

Participants generally agree on the role of semiconductor properties in determining LED color, but there is no consensus on the specifics of how power adjustments influence color emission.

Contextual Notes

Some assumptions about the relationship between power, electron energy levels, and color emission remain unaddressed, and the discussion does not resolve the complexities of how the eye perceives color.

Johnahh
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Am I right in thinking the chip controlling the LED is applying more or less power to make electrons go to different energy levels to emit different colours of light?
If anyone could clear this up for me it would be much appreciated.
 
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The color of an LED is determined by the properties of the chip producing the light, not the color of the plastic cover.
 
Thanks for the reply but what properties affect the colour? I was after the fundamentals of how the LED works.
Thanks
 
The basic property is the band gap in the semiconductor material that the LED is made from. Multi color LEDs have several LEDs made from different materials inside one package. Each one has a fixed color, but the brightness can be varied by controlling the current through it.

This is the same principle as the way computer or TV displays work, by changing the brightness of the red green and blue components of the light to produce the effect of any color.

To fully understand how this works, you also need to know how the eye (and brain!) detects the light and "decides" what color it is.
 

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