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How to Color LEDs

How to Color LEDs. Slide By Adam Bull. The approach is based on encapsulating semiconductor quantum dots and engineering their surfaces Doing so will effectively emit visible light when excited by near-ultraviolet light emitting diodes (LEDs). How to Color LEDs. Slide By Adam Bull.

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How to Color LEDs

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  1. How to Color LEDs Slide By Adam Bull

  2. The approach is based on encapsulating semiconductor quantum dots and engineering their surfaces • Doing so will effectively emit visible light when excited by near-ultraviolet • light emitting diodes (LEDs). How to Color LEDs Slide By Adam Bull

  3. How to Color LEDs • The quantum dots strongly absorb light in the near UV • range and re-emit visible light that has its color • determined by both their size and surface chemistry. Slide By Adam Bull

  4. How to Color LEDs • The discretized nature of quantum dot bands means that • the energy separation between the valence and conduction • bands (the band gap) can be altered with the addition or the • subtraction of just one atom, making for a size dependent • Band gap. • Predetermining the size of the QLEDs dots would • fix the emitted photon wavelength at the appropriate • specified color, even if it is not naturally occurring, • an ability limited only to dots. • The extremely small size and versatility of form for quantum dots allows them to be inserted into any medium necessary, paint, water, plastics and more. Slide By Adam Bull

  5. General Applications of LEDs • Traffic Lights • Currently Being Installed in California Architectural Lighting Used for Exterior and Interior Lighting The GardenLED Series by LEDtronics Only Requires Only 12-Volts DC to Operate • Remote Controls • Infrared LEDs • Sources: • “LED Uses 12 Watts of Power” By Loretta Conley <http://www.ledtronics.com/product_news/mae_article_020005.htm> • “California 'Green Lights' Energy Savings With New Traffic Signals” By Rob Schlichting <http://www.energy.ca.gov/releases/2002_releases/2002-03-14_led_signals.html> • Mills, Evan (2005). "The Specter of Fuel-Based Lighting". Science 308: 1263-1264. <http://en.wikipedia.org/wiki/LED#Blue_and_white_LEDs> Slide By Joe Iannucci

  6. General Applications of LEDs • Christmas Lights • Use About 1/10 of the Electrical Current Used By Incandescent Lights • Dot Matrix Arrangements • Used for Message Displays • Sources: • “What are LED Christmas Lights?” By Bryan Pedersen <http://www.wisegeek.com/what-are-led-christmas-lights.htm> • Mills, Evan (2005). "The Specter of Fuel-Based Lighting". Science 308: 1263-1264. <http://en.wikipedia.org/wiki/LED#Blue_and_white_LEDs> Slide By Joe Iannucci

  7. Applications of LEDs with Quantum Dots • Screens and Displays • Still in Development • Quantum dot-Organic Light-Emitting Devices (QD-OLED) Will Replace Liquid Crystal Displays (LCD) • Unlike LCDs, Quantum Dots Generate Their Own Light and Can be Tuned to Emit Any Color • Displays Thin and Very Bright • Sources: • “Quantum-Dot LED May Be the Future of Screens” < Slide By Joe Iannucci

  8. Applications of LEDs with Quantum Dots • White Light LEDs • Used to Emit White Light in Laptops, Car Interiors, Building Interiors, and Flashlights • Sources: • “Mighty Small Dots” <http://www.llnl.gov/str/Lee.html> Slide By Joe Iannucci

  9. White Light LEDs • Researchers at Vanderbilt University Have Recently Created a True White Light LED • Before This Development, White LEDs Had a Blue Tint • How Does It Work? • Extremely Small Quantum Dots Coat a Blue LED • Quantum Dots Glow White in Response to the Blue Light • Creates Light Similar to That Created by Common Incandescent Bulbs • Sources: • “Quantum Dots That Produce White Light Could Be the Light Bult’s Successor” By David F. Salisbury <http://www.physorg.com/news7421.html> • Mills, Evan (2005). "The Specter of Fuel-Based Lighting". Science 308: 1263-1264. <http://en.wikipedia.org/wiki/LED#Blue_and_white_LEDs> Slide By Joe Iannucci

  10. Advantages of LEDs • Can emit light of an intended color without the use of a filter. • Design of the package allows light to be focused. • Insensitive to vibration/shock. • Hard to break. • Long life span and give off less heat. Slide By Ryan McCombs

  11. Disadvantages of LEDs • Currently more expensive than traditional lighting. • “Performance largely depends on the ambient temperature of the operating environment.” Slide By Ryan McCombs

  12. Why use Quantum Dot LEDs? • Can be tuned to emit at any visible or infrared wavelength (color). • Can be fabricated into a great variety of forms and media. • Allows for incredible flexibility of form, letting quantum dots operate in matrixes, sheets, films, water solutions, gels, inks, and three-dimensional arrays. Slide By Ryan McCombs

  13. Advantages over Organic Light Emitting Diodes • Retain high quantum yields. • Retain luminosities over long lifetimes. • OLEDs have poor photostability and a short lifetime. Tiny quantum dots in a glass tube produce white light when stimulated by an ultraviolet laser beam. www.livescience.com Slide By Ryan McCombs

  14. Other Advantages of QLEDs • The Department of Energy has estimated that LED lighting could reduce U.S. energy consumption for lighting by 29 percent by 2025, saving the nation's households about $125 million in the process. • Infrared radiation in light bulbs produces large amounts of heat which accounts for low energy efficiency Slide By Ryan McCombs

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