Time-/environment-dependent multilevel optical encryption through photoluminescence enhancement of perovskite quantum dot/polymer composite via silver epoxy paste

초록

Perovskite quantum dot (PQD)/polymer nanocomposites have garnered significant attention in the field of advanced optical encryption due to their eminent photoluminescence (PL) properties and stability. Nonetheless, the strategies introduced often necessitate sophisticated experimental setup, presenting challenges for the practical application. Herein, we have designed a time/environment-dependent optical encryption methodology which leverages the PL enhancement of cesium lead bromide (CsPbBr<inf>3</inf>) PQD/polydimethylsiloxane (PDMS) film through the application of silver (Ag) epoxy paste (AEP). Following heat treatment under vacuum after AEP application on the film surface, diffused Ag ​+ ​ions efficiently passivated the surface defects of CsPbBr<inf>3</inf> PQDs, leading to an enhanced quantum yield of 20.7 ​%. AEP treatment was further exploited as a multilevel encryption technique by modulating the treatment and environmental conditions. Encrypted information was initially concealed under daylight and masked by fictitious information under UV light. This information was decrypted over time, exhibiting variances in PL intensity as quenching progresses. To prevent information leakage, the decrypted information could be reverted to the fictitious information via a rapid quenching of the AEP-treated film in aqueous environment. This research not only paves a new pathway toward an efficient defect passivation strategy for PQDs but also advances a straightforward, yet sophisticated optical encryption strategy. © 2025 Chongqing University

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