Forward voltage cut boosts LED efficiency

Osram Opto is claiming “one of the best values in the world in terms of forward voltage for blue high-current chips” following improvements in epitaxy, leading to up to 8% efficiency improvement.

Some devices have been getting the new die since August. Its blue Oslon Square now has a typical forward voltage of 2.87V instead of the data sheet value of 3.05V, for example. This drops to 2.78V at 85°C and, depending on operating point, efficiency gains of 6-8% are available.

The changes can be applied to any of its ‘UX:3’ process branded chips, white or blue, and there are further efficiency gains in the pipeline.

“In the laboratory we have already succeeded in further reducing the forward voltage by as much as 30mV”, said Osram epitaxy expert Dr Joachim Hertkorn – improving efficiency by another 1%. “In view of the speed with which this first step has been implemented, we are confident that the improved process can be transferred to production by the summer of 2015. Any further reductions in forward voltage will then only be marginal owing to the laws of physics.”