Solid‐state lighting (SSL) is now the most efficient source of high color quality white light ever created. Nevertheless, the blue InGaN light‐emitting diodes (LEDs) that are the light engine of SSL still have significant performance limitations. Foremost among these is the decrease in efficiency at high input current densities widely known as “efficiency droop.” Efficiency droop limits input power densities, contrary to the desire to produce more photons per unit LED chip area and to make SSL more affordable. Pending a solution to efficiency droop, an alternative device could be a blue laser diode (LD). LDs, operated in stimulated emission, can have high efficiencies at much higher input power densities than LEDs can. In this article, LEDs and LDs for future SSL are explored by comparing: their current state‐of‐the‐art input‐power‐density‐dependent power‐conversion efficiencies; potential improvements both in their peak power‐conversion efficiencies and in the input power densities at which those efficiencies peak; and their economics for practical SSL.

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The potential of III‐nitride based laser diodes (LDs) for solid‐state lighting (SSL) is discussed. State‐of‐the‐art blue LDs have higher efficiencies at high input power densities when compared to blue light‐emitting diodes (LEDs). This is because the processes that cause the drop in efficiency at high currents for LEDs are not present in the LD operated under stimulated emission. Projections of efficiency improvement show blue LDs have the potential to be nearly as efficient as blue LEDs and provide similar lumen output at much higher input powers. This result provides the possibility that white sources created from blue LD pumped phosphors could someday become a competitive and viable SSL source. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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