PL intensity of YAG:Ce3+ phosphor powder enhanced by Ag NPs with soluble and cracked polymer spacer

For the purpose of enhancing the photoluminescence (PL) intensity of YAG:Ce3+ phosphor powder by Ag nanoparticles (NPs), PVA and PVP polymer solutions were drop – coated onto the phosphor substrate to form the polymer spacers in this experiment. Due to the solubility and cracking performance, a short distance between Ag NPs and phosphor could be achieved. Two optimized structures of “phosphor substrate – PVA spacer – Ag/PVP layer” and “phosphor substrate – PVP spacer – Ag/PVP/PVA layer” were prepared. Their morphology, absorbance, PL intensity and distribution of elements were examined and compared. PVA spacer had a smooth surface while PVP spacer had large amounts of cracks. The sample with PVA spacer had a localized surface plasma resonance (LSPR) wavelength near 440 nm, while the sample with PVP spacer had a shorter LSPR wavelength near 430 nm, which was farther away from the exciting and emission wavelengths of YAG:Ce3+ phosphor. The samples with PVA and PVP spacers realized strongest PL intensity enhancement of 1.75 – fold and 2.08 – fold, respectively. That the sample with PVP spacer achieved higher enhancement ratio could be attributed to the dissolution of PVP spacer and its cracks, which supplied the channels for Ag NPs transporting closer to the phosphor substrate. The distribution of Ag element in the thickness direction testified it. The result demonstrated that the distance between Ag NPs and phosphor had more important effect on the PL intensity enhancement than the matching degree between LSPR wavelength and exciting (emission) wavelength of phosphor. It also indicates that soluble and cracked polymer spacer has its feasibility for industrial production in the area of PL intensity enhancement by LSPR owing to its simple preparation and low cost.