色彩可调Yb, Er共掺杂NaYF4上转换荧光材料的 合成及包装防伪应用

采用阴离子表面活性剂柠檬酸三钠和阳离子表面活性剂氯代十六烷基吡啶共同调介下的水热法,合成Yb,Er共掺杂NaYF_4上转换荧光材料(NaYF_4:Yb~(3+),Er~(3+));研究敏化剂Yb~(3+)和激活剂Er~(3+)在NaYF_4中的掺杂原子百分数(掺杂量)对NaYF_4:Yb~(3+),Er~(3+)上转换材料荧光性能的影响;以合成的NaYF_4:Yb~(3+),Er~(3+)为荧光填料,聚乙烯醇(PVA)为基材,通过流延法,制备了一系列不同荧光特性的复合薄膜。研究结果表明:随着Yb~(3+)含量的提高,NaYF_4:Yb~(3+),Er~(3+)上转换材料发光强度先增大后减小,当Yb~(3+)掺杂量为30%时,荧光强度达到最大;另外,随着Yb~(3+)掺杂量从10%提高到98%,绿色荧光与红色荧光强度的比值(绿红比)逐渐减小,上转换材料发光颜色由绿色变为黄色再变为橙色。随着Er~(3+)掺杂量的增加,荧光强度同样先增大后减小,当Er~(3+)掺杂量为1%时,荧光强度达到最大;且Er~(3+)掺杂量的增加同样会使绿红比降低。所制备的复合薄膜透明性好,且具有易调控、易识别、难察觉的上转换荧光特性,预期在包装防伪领域有很好的应用前景。

Synthesis of Yb, Er Co-Doped NaYF4 with Tunable Up-Conversion Emission for Anti-Counterfeiting Application

Yb, Er co-doped NaYF4 (NaYF4: Yb3+, Er3+) up-conversion phosphors (UCPs) were synthesized through hexadecylpyridinium chloride and tri-sodium citrate binary cationic/anionic capping agent assisted hydrothermal reaction. The effects of doping amount of sensitizer (Yb3+) and activator (Er3+) on luminescence properties of NaYF4: Yb3+, Er3+ were systematically investigated. A series of luminescent polymer composite films were prepared by aqueous solution casting method employing poly(vinyl alcohol) (PVA) as a matrix polymer and different kind of UCPs as the filler. It was found that the fluorescent intensity of the UCPs was firstly increased and then decreased with the increasing of Yb3+ doping amount. With the doping amount of Yb3+ kept at 30%, the resultant UCPs showed the strongest fluorescent intensity. Besides, the increasing of Yb3+ doping amount from 10% to 98% led to the decrease of the green to red emission ratios and the resultant UCPs exhibited different emission colors ranging from green to yellow and then to orange. The effect of Er3+ doping amount on the fluorescent property of UCPs was also examined. The tendency was similar to that of Yb3+ doping amount effect. With the increasing of Er3+ doping amount, the fluorescent intensity of the UCPs was firstly increased and then decreased. With the doping amount of Er3+ kept at 1%, the resultant UCPs showed the strongest fluorescent intensity. The doping amount of Er3+ also affected the green to red emission ratios, which endowed the UCPs with different up-conversion emission. The transparent PVA composite films with tunable up-conversion emission may find practical application in the field of anti-counterfeiting packaging.