Herein, we report
a siloxane-encapsulated upconversion nanoparticle
hybrid composite (SE-UCNP), which exhibits excellent photoluminescence
(PL) stability for over 40 days even at an elevated temperature, in
high humidity, and in harsh chemicals. The SE-UCNP is synthesized
through UV-induced free-radical polymerization of a sol–gel-derived
UCNP-containing oligosiloxane resin (UCNP-oligosiloxane). The siloxane
matrix with a random network structure by Si–O–Si bonds
successfully encapsulates the UCNPs with chemical linkages between
the siloxane matrix and organic ligands on UCNPs. This encapsulation
results in surface passivation retaining the intrinsic fluorescent
properties of UCNPs under severe conditions (e.g., 85 °C/85%
relative humidity) and a wide range of pH (from 1 to 14). As an application
example, we fabricate a two-color binary microbarcode based on SE-UCNP
via a low-cost transfer printing process. Under near-infrared irradiation,
the binary sequences in our barcode are readable enough to identify
objects using a mobile phone camera. The hybridization of UCNPs with
a siloxane matrix provides the capacity for highly stable UCNP-based
applications in real environments.
We report on the effect of linkage between quantum dot (QD) and siloxane matrix by preparing two different QD/siloxane films. One has chemical linkages between QD and siloxane matrix, and the other has no chemical linkages between QD and siloxane matrix. The QD/siloxane (methacryl) film, which has the chemical linkages, exhibits no degradation of photoluminescence (PL) quantum yield (QY) under heat or moisture condition for over 1 month, while the QD/siloxane (epoxy) film, which has no linkages, shows drastic decreased of PL QY. The chemical linkages between QD and siloxane matrix that makes effective siloxane passivation layer intact on the surface of QDs in QD/siloxane (methacryl) film. Given its exceptional stability with the help of linkages between QD and siloxane matrix, we expect that the QD/siloxane (methacryl) film is best fitted in PL‐type down‐conversion layer for display applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.