New Technique Boosts Output of Green LEDs

Achievement date: 
2013
Outcome/accomplishment: 

A team with the Lighting Enabled Systems & Applications ERC (LESA) have pioneered a technique that’s allowed several improvements to the brightness and quality of green light-emitting diodes, or LEDs. Smart Lighting is an NSF-funded Engineering Research Center (ERC) based at Rensselaer Polytechnic Institute.

Impact/benefits: 

High-efficiency green LEDs have proven challenging for researchers to build. Once green LEDs are as easy to design and manufacture as blue and red LEDs, it should lead to development of a new generation of low-cost, high-performance displays and lighting applications.

Explanation/Background: 

To achieve the marked green LED improvements, the ERC researchers used a special pattern in the LED device, at the nano scale (a range of measurement usually considered to be in the range of zero to a few hundred nanometers). This pattern was placed between the LED’s sapphire base and the layer of gallium nitride (GaN) that gives the device its green hue when lit.

Using the nano-patterning technique, the LESA team at Rensselaer was able to create notable increases in light output and measures of overall efficiency. The innovation puts lighting technologists a few steps closer to realizing the ultimate achievement in LEDs, creating a “true white” LED by combining red, green, and blue. Currently, “white” is created by adding yellow phospors to blue LEDs, resulting in a bluish tint to LED devices marketed as white. Once green LEDs are perfected and inexpensive, they can be mixed with red and blue LEDs to accurately reproduce virtually every color visible to the human eye.