Lattice Softening Effects in Perovskite Nanocrystals: a Strategy for Lifetime-Encoded Unicolour Security Tags

Sergii Yakunin^a^,^b, Jana Chaaban^c, Bogdan Benin^a^,^b, Ihor Cherniukh^a^,^b, Caterina Bernasconi^a^,^b, Annelies Landuyt^a^,^b, Yevhen Shynkarenko^a^,^b, Sami Bolat^b, Christoph Hofer^d, Yaroslav Romanyuk^b, Stefano Cattaneo^d, Sergey Pokutnyi^e, Richard Schaller^f^,^g, Maryna Bodnarchuk^a^,^b, Dimos Poulikakos^c, Maksym Kovalenko^a^,^b

^aETH Zurich, Laboratory of Inorganic Chemistry, Department of Chemistry & Applied Biosciences, Vladimir-Prelog-Weg, 1, Zürich, Switzerland

^bLaboratory for Thin Films and Photovoltaics, Empa – Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland, Überland Strasse, 129, Dübendorf, Switzerland

^cLaboratory of Thermodynamics in Emerging Technologies, ETH Zürich, Switzerland, Sonneggstrasse, 3, Zürich, Switzerland

^dSwiss Center for Electronics and Microtechnology (CSEM), Center Landquart, CH-7302 Landquart, Switzerland

^eDepartment of Theoretical Physics Nanosystems, Chuiko Institute of Surface Chemistry of National Academy of Sciences of Ukraine, 17 General Naumov Str., Ukraine

^fArgonne National Laboratory, Center for Nanoscale Materials, 9700 South Cass Avenue Bldg 440, Lemont, Illinois 60439, United States

^gDepartment of Chemistry, Northwestern University, United States, Sheridan Road, 2145, Evanston, United States

Proceedings of Internet Conference for Quantum Dots (iCQD)

Online, Spain, 2020 July 14th - 17th

Organizers: Quinten Akkerman, Raffaella Buonsanti, Zeger Hens and Maksym Kovalenko

Oral, Sergii Yakunin, presentation 015
Publication date: 3rd July 2020

The tunability of semiconductors quantum dots (QDs) is generally restricted by Fermi’s Golden Rule — altering the bandgap concomitantly alters photoluminescent (PL) lifetime. Herein, we present a strategy to circumvent this restriction, which can be realized with the soft and flexibile crystal lattice of perovskite nanocrystals (NCs). Through the partial substituion of formamidinium (FA) for ethylenediammonium {en}, “hollow” {en}FAPbBr₃ NCs can be generated and emission wavelength matched to CsPbBr₃ NCs while maintaining drastically different PL lifetimes.^1,2 We attribute this to two potentially co-existing effects: increased phonon-exciton interaction and additional energy levels for the excitonic transition. This unique materials system allows us to push the young yet promising field of lifetime-encoded security tags forward. Our proof-of-principle security system is based on high-resolution electrohydrodynamically printed unicolour multi-fluorescent-lifetime codes that can be deciphered with either commercially available time-correlated single-photon counting fluorescence-lifetime imaging (TCSPC-FLI) microscopy or our time-of-flight (ToF)-FLI prototype. We believe that this innovative approach may provide a new tool for securing global trade against counterfeit goods and currency.

References:

[1] Loredana Protesescu, Sergii Yakunin, Maryna I Bodnarchuk, Franziska Krieg, Riccarda Caputo, Christopher H Hendon, Ruo Xi Yang, Aron Walsh, Maksym V Kovalenko. Nanocrystals of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, and I): Novel Optoelectronic Materials Showing Bright Emission with Wide Color Gamut. Nano Lett., 2015, 15, 3692-3696

[2] Loredana Protesescu, Sergii Yakunin, Maryna I Bodnarchuk, Federica Bertolotti, Norberto Masciocchi, Antonietta Guagliardi, Maksym V Kovalenko. Monodisperse formamidinium lead bromide nanocrystals with bright and stable green photoluminescence. J. Am. Chem. Soc., 2016, 138 , 14202-14205

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