February 2019
Vol 5, Issue 2

About The Cover

Cover image expansion

ONLINE COVER Phosphorescence—which, unlike fluorescence, involves reemission of light on a slower timescale—is used in glow-in-the-dark products, including illuminating emergency signs. It is also used for information storage purposes such as stamp detection. Easier and less expensive fabrication methods for phosphorescence systems have been created via organic emitters but achieving visible organic phosphorescence under ambient conditions remains challenging. In a new study, Gmelch et al. report a "new milestone" in organic luminescent labeling. They used a simple device structure made of highly available materials, through which ultrathin, flexible and transparent luminescent coatings could be generated. Their labeling device is fast and capable of printing more than 40 cycles of information onto any substrate of any size at high resolution (more than 700 dpi). Using light alone, any luminescent image can be printed and erased without the need of ink, via their approach. This concept say Gmelch et al., represents a way to produce luminescent on-demand tags and is a promising replacement for conventional labeling techniques. [CREDIT: MAX GMELCH AND HEIDI THOMAS/TECHNISCHE UNIVERSITÄT DRESDEN (TUD)]