LEDs seem to reach a point where more electricity no longer imparts the same kick and light production levels-off. Now a team of researchers from California and Japan has devised a new design for green and blue LEDs that avoids much of this vexing efficiency droop. The findings will be presented at the Conference on Lasers and Electro-Optics (cleo:2012), taking place May 6-11 in San Jose, Calif. UCSB researchers have found that by changing the orientation of the crystal structure in semiconductor films, the team created LEDs with high efficiency and extremely low droop. Droop, which is a dramatic drop in efficiency at high currents, is one problems limiting the growth of the solid-state lighting market.
The UCSB researchers’ LEDs have non-traditional, tilted crystal orientations that they claim decreases the effect of the field. In this way the researchers were able to produce LEDs that exhibited some of the lowest reported measures of droop. Using this approach the team was also able to fabricate LED chips that are smaller than standard commercial LEDs. So manufacturers could theoretically use fewer LEDs running at higher power to produce the same light output. Ultimately this could cut down on manufacturing costs.