March 12, 2014
Researchers Develop Brighter LEDs That Use Less Energy
redOrbit Staff & Wire Reports - Your Universe Online
However, LEDs do have one specific weakness – they are extremely sensitive to variations and spikes in power, and require a driver that ensures a constant supply of power at all times. This driver, which converts alternating current to direct current with a reduced voltage, has a profound influence on the light yield and lifetime of the LED lamp. As a result, the demands placed on the driver electronics are significant, prompting researchers at the Fraunhofer Institute for Applied Solid State Physics (IAF) in Freiburg to focus their work on voltage transformers with gallium nitride (GaN) transistors.
Components made of GaN can operate at higher currents, voltages and temperatures than standard silicon transistors.
During their study, the IAF researchers found that the drivers developed using this new semiconductor material were highly robust.
“Heat plays a role both in the brightness and the service life of LED lamps,” said Dr. Michael Kunzer, group manager at Fraunhofer IAF.
Gallium nitride transistors can also switch at high frequencies, something that strongly impacts the size of the coils and condensers built into the drivers for energy storage. In fact, in a GaN-based driver, the switch speed can be made as much as a factor of 10 faster than that of its silicon equivalent, the researchers said.
“Applied to a smaller surface, this means it is possible to make switching cheaper. The whole LED lamp can be made lighter and more compact while delivering the same or even improved illumination,” Kunzer said.
Since the energy storage component plays a decisive role in manufacturing costs, this could have an highly positive effect on the end price of the LED.
Thanks to the new semiconductor material’s useful properties, Kunzer and his team were able to boost the efficiency of the GaN driver to 86 percent – a one to four percentage point improvement over a silicon equivalent.
The researchers were also able to increase the light output of the GaN transistor LED lamps when compared with a silicon equivalent, raising the output from around 1000 lumen to 2090 lumen.
“In principle, the higher the light yield and efficiency, the lower energy consumption,” Kunzer noted. “20 percent of energy consumption worldwide can be attributed to lighting, so it’s an area where savings are particularly worthwhile.”
“If you think that by 2020 LEDs will have carved out a market share of almost 90 percent, then it is obvious that they play a significant role in protecting our environment.”
The researchers will be showcasing their work during the Hannover Messe conference April 7-11.