Mie-Resonant Rutile TiO2 Nanospheres for Unclonable Structural Colors

Jeong Bin Moon, Seung Jea Lee, Seung Hyun Kim, Yechan Chang, Hyerim Hwang, Gi Ra Yi

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Monodisperse carbon-embedded rutile TiO2nanospheres were synthesized through the sol-gel reaction of titanium alkoxide in concert with dodecylamine and the subsequent thermal annealing process in inert gas. Since dodecylamine was uniformly carbonized in nanospheres, the growth of rutile crystals was limited to ∼50 nm in the thermal annealing process, which enabled us to keep the spherical shape of nanospheres. Due to the size and shape uniformity, colloidal films of these rutile TiO2nanospheres showed unique Mie-resonant structural colors, in which multiple scattering was suppressed due to carbon embedded in nanospheres. Due to the high refractive index of rutile TiO2, there were multiple backscattering peaks in the visible region, which make it extremely difficult to replicate the colorimetric information when they were utilized as encryption inks. Finally, we demonstrated that IR-reflective carbon-embedded rutile TiO2nanospheres can be used as automotive paints, which can be distinguishable at night for light detection and ranging (LiDAR) systems.

Original languageEnglish
Pages (from-to)7897-7905
Number of pages9
JournalChemistry of Materials
Volume34
Issue number17
DOIs
StatePublished - 13 Sep 2022

Bibliographical note

Funding Information:
This work was supported by the National Research Foundation of Korea (NRF) (2017M3A7B8065528, 2021R1A2C3013800, 2019K1A3A1A21032033), the Korea Toray Science Foundation, and Samsung Electronics.

Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.

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