Highly Secure Plasmonic Encryption Keys Combined with Upconversion Luminescence Nanocrystals

Kisun Park, Minji Park, Ho Seong Jang, Ji Hun Park, Jaekyun Kim, Younghak Cho, Il Ki Han, Dongjin Byun, Hyungduk Ko

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)


This study proposes a novel and highly secure encryption technology based on plasmonic-enhanced upconversion luminescence (UCL). The technology can be realized by a disordered plasmonic nanostructure composed of a transferred metal nanoparticle–UC nanocrystals (UCNC)–metal (tMUM) film using the graphene transfer process, in which the metal nanoparticles that formed on the graphene layer are transferred using Scotch tape. The plasmonic tMUM film strongly enhances the UCL by a factor of 200 mainly because of the excitation of the gap plasmon polaritons. Meanwhile, the UCNCs in direct contact with the metal film result in luminescence quenching caused by a nonradiative process. Herein, a highly secure anti-counterfeit film is developed, which is very hard to duplicate and cannot be reused, using two conflicting features (i.e., emission enhancement and quenching phenomena). The UCL is strongly amplified only when the first (i.e., a random metal nanoparticle array) and second (i.e., UCNCs on a Ag film) codes are very precisely overlapped as designed, thereby generating the originally designed final code. Therefore, our novel high-level security device is expected to be easily applied to protect and identify genuine products.

Original languageEnglish
Article number1800369
JournalAdvanced Functional Materials
Issue number21
Publication statusPublished - 2018 May 24


  • encryption
  • graphene transfer
  • plasmonic enhancement
  • upconversion

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics


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