The Faces of Ultraviolet (slate.com)

There are at least some sunscreens with ingredients (such as titanium dioxide) which will help reflect some UV light. I suspect it is the combination of absorbing molecules and reflective materials which will make up a better sunscreen.

I suspect many cell phone cameras do have a UV filter, however it would be filtering out the UV. If UV does make it to the sensor then you could do the filtering and band shifting in software.