Synthesis and characterization of NaYF₄:Yb, Er up-conversion phosphors/poly(vinyl alcohol) composite fluorescent films

Luminescent polymer composite films were prepared by aqueous solution casting method employing poly(vinyl alcohol) (PVA) as a matrix polymer and NaYF₄:Yb, Er up-conversion phosphors (UCPs) as the filler. A series of luminescent UCP/PVA composite films were obtained by varying the amount of the UCP filler. The effects of UCP incorporation on the structure, morphology, thermal stability and optical properties were also examined. The well-dispersed UCPs in the polymer matrix enhanced the thermal stability of composite films due to hydrogen bonding between the PVA and UCPs. Besides, the incorporation of UCPs did not greatly decrease the transparency of films but imparted fluorescent properties to the polymer matrix. The fabricated UCP/PVA composite films exhibited strong up-conversion photoluminescence upon the 980 nm laser excitation. The UCP/PVA composite fluorescent films may have promising application in anti-counterfeiting packaging and in other optics related fields.