You want to go in the other direction - ultra violet. There are LEDs that are in the 360-380nm range that don't produce visible light, but will still charge glo

You want to go in the other direction - ultra violet. There are LEDs that are in the 360-380nm range that don't produce visible light, but will still charge glow-in-the-dark materials. The higher the frequency, the less efficient it will be, however, and below 320nm they can be hazardous to skin or eyes.