Numerous photochemical applications require UV radiation at wavelengths below 365 nm. At this range, LED technology used to be inferior to classic UV sources (predominantly mercury vapour lamps) as such LEDs were either unavailable or emitting an extremely low output.

Subsequent to the development of new semi-conducting materials, LEDs have caught up considerably. Today there are a number of specialised deep-UV LEDs at wavelengths between 250-365 nm, offering output around 10-50 mW. Where necessary, these can be bundled and used in preparative scale irradiation effectively.