Green high‐power light sources using InGaN multi‐quantum‐well structures for full conversion

We investigate the possibility to obtain efficient green light sources for high-power applications by full luminescence conversion via InGaN/GaN multi-quantum-well (MQW) structures. Using an ultraviolet (UV) light-emitting diode (LED) for optical pumping of a forty-period (40x) MQW structure emitting in the green spectral range, we show that a luminous flux comparable to the best reported values for direct green LEDs can be achieved. The position of the efficiency maximum on the excitation density axis is shifted by an order of magnitude to an equivalent of 28 Acm–2 while maintaining comparable absolute values. We propose the concept of processing suitable platelets placed directly on a pump LED as a general experimental tool to determine absolute efficiency values of structures that cannot be pumped by electrical means (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)