III-V materials are widely used for LEDs. Depending on the material bandgap, InGaN and AlGaInP alloys are used for visible spectrum LEDs, while AlGaN alloys are used for UV LEDs. The state-of-art data shows that in the green spectral range (where human eyes are most sensitive to), the external quantum efficiency (EQE) of conventional LEDs drop for both families of materials. This phenomenon is known as ‘green gap’. This document provides a brief background into the technical challenges that inspired the Green Gap E241 project.