I don't know that it is "cheating" to add an emitter layer.
From my limited i.e. high school understanding of fluorescence it goes something like this....
When electrons from light hit substances they impart energy.
In a fluorescent material this causes the electrons in the material getting hit to get excited and to move away from their core.
When they lose that energy and fall back to their original positions they "emit" light.
Fluorescence occurs when the electrons fall back to their original positions immediately
Phosphorescence occurs when the electrons have a delayed response in falling back to their original positions i.e. phosphorescent watch dials that glow all night, long after their exposure to light has occurred.
Whether the plexi glass is truly fluorescent is another matter, but for true fluorescence I think that adding an emitter is a good idea. I could be completely wrong in this but figured I would add my 0.02 cents anyway

Cary