Introduction . The III-nitride light-emitting diodes (III-N LEDs) coated with phosphors are currently the most efficient white light sources for general lighting1 , 2 , 3 , 4. The most efficient violet III-N LEDs reach approximately 80% of both external quantum efficiency and wall plug efficiency5 , 6 , 7 , 8. However, there is one crucial disadvantage of using LEDs for general lighting. The electric power in the electrical grid is distributed as alternating curre...