Dual-stimuli responsive photonic barcodes based on perovskite quantum dots encapsulated in whispering-gallery-mode microspheres

Micro/nanoscale photonic barcodes hold great potential for broad applications in items tracking, multiplexed bioassays and anti-counterfeiting. The ever-increasing demand in advanced anti-counterfeiting applications calls for micro/nanoscale barcodes with accurate recognition, large encoding capacity and high security level. Here, we proposed a strategy to construct the dual-stimuli responsive photonic barcodes based on the perovskite quantum dots (PQDs) doped polymer whispering-gallery-mode (WGM) microcavities via swelling-deswelling method. Benefiting from the well-defined spherical microcavities, the photoluminescence (PL) spectra of as-prepared composites exhibit a series of sharp peaks characteristics resulting from the effective WGM modulation, which constitutes the fingerprint of a specific resonator and thus allows a definition of photonic barcodes. On this basis, we achieved responsive photonic barcodes based on the volatile polar-solvent-controlled luminescence in the microspheres benefitting from the space-confined microcavities and the ionic feature of the PQDs. Moreover, the light-controlled photonic barcodes have further been acquired through reversibly regulating the inactivation and activation of the energy transfer (ET) process between the PQDs and photochromic dyes. The well-established protocols of PQDs@WGM enable the development of distinct responsive barcodes with multi-responsive features, which will pave an avenue to new types of flexible WGM-based components for optical data recording and security labels.