Owing to the existence of Ag NCs, these Ag NC composite polymer fibers emit pink luminescence. Fig. 3a shows the evolution of luminescence spectra of the Ag(I)-rich electrospun polymer fibers with UV light irradiation. It can be found that there is no photoluminescent band observed before UV light irradiation, and with irradiation time increasing, a peak at 576 nm appeared and gradually increased, indicating that Ag NCs were accumulating. The luminescence peak displayed a 14 nm redshift within the photo-induced reduction process, which is mainly derived from the size growth of Ag NCs. As reported earlier, the maximum emission wavelength exhibited redshifts as the size of Ag NCs increased [34]. The peak intensity reached maximum when the irradiation time was 100 min (Fig. 3b), indicating the optimal irradiation time of 100 min for the highest luminescence. In addition, it is observed a peak increasing in intensity but static in peak position at 690 nm, nevertheless, the 690 nm peak could be found in a few literatures [1], [44] and [45]. So far, we can't give any reasonable explanations on the 690 nm peak.