The rise of
counterfeits is a serious problem affecting all types of products
ranging from legal documents, currencies, to high-end branded
goods. For example, UV-to-visible down-conversion fluorescent dyes have
been used as security features in many applications like currencies,
identity cards and banking accounts. Though various measures have been
implemented to identify the originals, some of these measures can be
very easily duplicated. The stability of these counterfeits materials
may also be an issue.
Our NIR-to-visible up-conversion nanoparticles can be developed into a new generation of
anti-counterfeiting inks. Our nanoparticles may be a replacement to the
fluorescent dyes that are currently used in currency notes. The
nanoparticles can also be dispensed though ink-jet printing. Our
nanoparticles may easily be dispersed in proper solvents.