Cover Picture: Phys. Status Solidi RRL 7‐8/2009

The Rapid Research Letter by Regina Mueller‐Mach et al. on p. 215ff. gives a first account of a novel concept for making light emitting diodes (LEDs) at wavelengths at which neither InGaN nor AlGaInP ones are efficient, the so‐called yellow gap: A nitride phosphor with peak emission at 590 nm in the form of a dense ceramic – Lumiramic™ – is attached to a highly efficient blue emitting InGaN diode, so that all blue light is converted, i.e., full conversion is achieved. A total external quantum efficiency (amber photons per electron) of 32% has been reached; despite the huge quantum deficit and the low lumen equivalent, this results in 300% efficiency as compared to the best direct AlGaInP LED.