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Intense hydrochromic photon upconversion from lead-free zero-dimensional metal halides for water detection and information encryption
SCI Impact Factor
32.086
Authors
J. H. Han, T. Samanta, H. B. Cho, S. W. Jang, N. S. M. Viswanath, Y. R. Kim, J. M. Seo, and W. B. Im*
Journal
Adv. Mater.
Status
published
Page
2302442
Year
2023

Hydrochromic materials that change their luminescence color upon exposure to moisture have attracted considerable attention owing to their applications in sensing and information encryption. However, the existing materials lack high hydrochromic response and color tunability. This study reports the development of a new and bright zero-dimensional (0D) Cs3GdClmetal halide as the host for hydrochromic photon upconversion in the form of polycrystals (PCs) and nanocrystals (NCs). Lanthanides co-doped cesium gadolinium chloride metal halides exhibit upconversion luminescence (UCL) in the visible–infrared region upon 980 nm laser excitation. In particular, Yb3+ and Er3+ co- doped PCs exhibit hydrochrmic UCL color change from green to red. These hydrochromic properties are quantitatively confirmed through sensitive detection of water in the tetrahydrofuran solvent via UCL color changes. This water-sensing probe exhibits excellent repeatability and is particularly suitable for real-time and long-term water monitoring. Furthermore, the hydrochromic UCL property is exploited for stimuli-responsive information encryption via cyphertexts. These findings will pave way for the development of new hydrochromic upconverting materials for emerging applications, such as noncontact sensors, anticounterfeit and information encryption.