Role of carbon quantum dots and film thickness on enhanced UV shielding capability of flexible polymer film containing carbon quantum dots/N-doped ZnO nanoparticles

We report a simple method for preparing flexible polymer film containing carbon quantum dots/N-doped ZnO (CQD/N-ZnO) nanoparticles, as UV shielding material. The polymer film showed an enhanced UV shielding capability with increasing of CQD/N-ZnO nanoparticles. The maximum of 47% of UV shielding capability was achieved with 1 wt.% of CQD/N-ZnO nanoparticles and two-order enhancement was achieved by controlling film thickness to 250 mu m. It was found that CQDs plays important role to promote compatibility of hydrophilic ZnO into hydrophobic polymer matrix without disturbing the transparency of the film. An excellent UV shielding capability of 85% and 92% was witnessed in 250 mu m thick polymer film under a UV lamp and direct daylight, respectively.