Dual interfacial H-bonding-enhanced deep-blue hybrid copper–iodide LEDs

If you look at the figures provided in the link, you will see that the intensity of the light below 400nm is far lower than anything else that is available.

These are also able to operate for far longer without degrading as opposed to some of the current compromises which use diodes that blast out UV and are then mitigated with flim or a bulb that filters it out.