Luminescent polystyrene films, a novel way to reduce styrofoam residues

Polystyrene (PS) films doped with blue, yellow and red organic pigments have been deposited on glass and on commercial LED chips by spray pyrolysis using recycled PS as precursor, at deposition rates between 100 and 200 Å/s. Doped films have roughness between 100 and 2500 Å depending on the kind of pigment used; the surface morphology shows that the organic pigments incorporate into the polystyrene host forming globular particles of about 2 μm in diameter. The organic pigments used have luminescent emissions peaked at 440, 509 and 590 nm. The introduction of the proper combination of pigments on the PS film deposited on the LED chips renders a white light emission with (0.29, 0.37) and (0.30, 0.33) CIE (Commission international de l' éclairage) color coordinates. It was determined that the exposure to violet light degrades the luminescent characteristics, however, blue light is not energetic enough to cause a degradation of the luminescent layer over similar period of time.