Via Compound Interest comes a really cool chart and post explaining the basic chemistry in making different colors of LED lights:
… you’ve may well have started seeing Christmas lights starting to appear adorning houses and Christmas trees. How do these lights actually work, and how can they be made to produce such an array of colours? This graphic takes a look at the chemistry.
The colours obtained from LEDs are determined by the semiconducting materials used. As you can see in the graphic, there’s not just one material used for all of the different colours, but a range of possibilities. By using different materials, and adding different impurities to these materials, we can change the size of the band gap – that is, the size of the energy difference between the n-type layer and the p-type layer. The bigger this band gap, the shorter the wavelength of light produced by the LED. So for a red LED, a relatively small band gap is required. For blue LEDs, a larger band gap is needed.
See the entire article for additional information, and here for a PNG image and this link for a PDF of the chart. CC-Attrib-NC-ND 4
(thanks to THB for the tip)
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