Department of Materials and Metallurgical Engineering, South Dakota School of Mines and Technology, 501 St Joseph Street, Rapid City, SD 57701, USA.
Nanotechnology. 2012 May 11;23(18):185305. doi: 10.1088/0957-4484/23/18/185305. Epub 2012 Apr 13.
Two methods of direct-write printing for producing highly resolved features of a polymer impregnated with luminescent upconversion phosphors for security applications are presented. The printed polymer structures range in shape from features to text. The thin polymer features were deposited by direct-write printing of atomized material as well as by screen-printing techniques. These films contain highly luminescent lanthanide-doped, rare-earth nanocrystals, β-NaYF₄:3%Er, 17%Yb, which are capped with oleic acid. This capping agent allows the nanocrystals to disperse throughout the films for full detailing of printed features. Upconversion of deposited features was obtained using a 980 nm wavelength laser with emission of upconverted light in the visible region at both 540 and 660 nm. Features were deposited onto high bond paper, Kapton®, and glass to demonstrate possible covert and forensic security printing applications, as they are printed in various features and invisible to 'naked-eye' viewing at low concentrations of nanocrystals.
介绍了两种用于生产经上转换发光磷光体浸渍的聚合物的高分辨率特征的直写打印方法，用于安全应用。打印的聚合物结构的形状从特征到文本不等。通过雾化材料的直写打印以及丝网印刷技术沉积了薄的聚合物特征。这些薄膜含有高度发光的镧系掺杂、稀土纳米晶体，β-NaYF₄:3%Er, 17%Yb，用油酸进行了封端。该封端剂允许纳米晶体在整个薄膜中分散，以实现打印特征的完全细化。使用 980nm 波长的激光实现了沉积特征的上转换，在可见区域发出 540nm 和 660nm 的上转换光。将特征沉积在高结合纸上、Kapton®和玻璃上，以展示可能的隐蔽和法医安全打印应用，因为它们以各种特征打印，并且在纳米晶体浓度低时肉眼不可见。
