Fig. 4. (a) Digital photography of PU:Eu3+ complex-3 wt% film when exposed to UV light at 365 nm, (b) EDX spectrum, (c) S, (d) C, (e) O, (f) N and (g) Eu element distribution map of the surface of PU:Eu3+ complex-3 wt% film, the photoluminescence (h) excitation and (i) emission spectra of PU:Eu3+ complex films (Eu3+ complex content: 1, 2, and 3 wt%).
