Green Light LEDs

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Green Light LEDs

• Andrew Pottorff

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Green Light Challenge

• Green LEDs were previously to hard to manufacture
• Previously made green LEDs werent strong enough
  or bright enough to match red and blue
• Problem was circumvented by aiming the blue light
  at a yellow phosphor to emit green light
• This produces white light, but it is wasteful
  compared to using a white light based off three
  LEDs

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Why?

• Green LEDs allow white light via RGB mix
• Cheaper and more efficient than incandescent
• Allows variation for lighting during different
  times of day
• No toxic heavy metals involved
• Longer lasting

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The Numbers

• Department of Energy estimates the following
• Could save U.S. 120 billion over the next 20
  years
• Reduce emissions by 246 metric tons of carbon
• Emission reduction is equal to 5 of the total
  U.S. total emissions from years 1850-2000

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Old Development

• U.S. Department of Energys NREL (National
  Renewable Energy Laboratory) developed the
  technology to absorb green light
• If layers of lattice dont match up by leaving
  too big a gap, the efficiency falls to almost
  zero
• Combined layers of different lattice sizes in
  order to efficiently absorb light

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New Development

• NREL researcher Angelo Mascarenhas thought to
  reverse the process
• Mascarenhass idea was to send a current through
  appropriately spaced layers of lattice to obtain
  green light
• He managed to produce green light on the very
  first try

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Forward Motion

• NREL wants to produce a fourth color to make the
  white light even whiter
• They would then arrange the four colors in a
  beehive structure so light will look white from a
  distance
• Researchers want to make their LED light
  intelligent
• The lights will dynamically match the ratio of
  colors to the time of day, allowing increased
  visibility

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Sources

• http//www.gizmag.com/first-green-led-light-manufa
  ctured/14761/
• http//www.azom.com/news.asp?newsID18833