Quantum Dots Enhance LED Lighting

Tiny semiconductor crystals could produce better colors for lighting and computer displays

3 min read
Quantum Dots Enhance LED Lighting

9 December 2009—The next big thing in solid-state lighting may be exceedingly tiny—the quantum dot. Researchers from around the world gathered at the Materials Research Society fall meeting in Boston last week to discuss the progress they're making in using quantum dots to enhance the color and efficiency of light-emitting diodes (LEDs).

Quantum dots are nanometer-size bits of semiconductor material, such as cadmium selenide, that fluoresce when excited by photons or electrons. By choosing a certain material and a certain size, researchers can precisely tune the wavelength of light emitted. In general, a dot that's 2 nanometers in diameter emits blue light, a 4-nm dot emits green, and a 6-nm dot emits red.

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The State of the Transistor in 3 Charts

In 75 years, it’s become tiny, mighty, ubiquitous, and just plain weird

3 min read
A photo of 3 different transistors.
iStockphoto
LightGreen

The most obvious change in transistor technology in the last 75 years has been just how many we can make. Reducing the size of the device has been a titanic effort and a fantastically successful one, as these charts show. But size isn’t the only feature engineers have been improving.

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