Upconversion Nanoparticle-Integrated Bilayer Inverse Opal Photonic Crystal Film for the Triple Anticounterfeiting

Abstract

Optical anticounterfeiting plays a vital role in information security because it can be recognized by the naked eye and is difficult to imitate. Herein, a hydrophilic modified upconversion nanoparticle (M-UCNP)-integrated bilayer inverse opal photonic crystal (IOPC) film was designed in which the luminescent M-UCNPs were deposited on the surface of the optimized bilayer structure with double photonic stop bands. The structure which can modulate light to produce structural colors can also enhance the upconversion luminescence (UCL) to improve the anticounterfeiting effect synergistically. On the one hand, the reflection colors from green to blue were observed in the specular angles on the front (540-layer) of the film. Meanwhile, the scattering colors under nonspecular angles from red to blue on the back (808-layer) appeared in the natural light. On the other hand, the bilayer structure in which the 808-layer functions as a “secondary excitation source” to improve the intensity of the excitation light on M-UCNPs and the 540-layer reflects the emission light of the M-UCNPs to enhance the UCL intensity endows the film with good night vision ability. Finally, the dual-mode structural colors and enhanced UCL of the patterned film work together to realize triple anticounterfeiting in banknotes.

Achieving Functionality and Multifunctionality through Bulk and Interfacial Structuring of Colloidal-Crystal-Templated Materials

“…Here, high complexity has been achieved by preparing Janus-like bilayer 3DOM films with two different pore sizes to achieve different coloration from the front and the back of the film, and by integrating luminescent components, including upconversion nanoparticles. 106 Specific patterns can be inscribed into the polymeric 3DOM films by UV laser irradiation at various stages during the film assembly and processing. 3DOM particles with structural color have been used as barcodes in various applications, including cell capture, such as binding and detection of circulating tumor cells.…”

“…Besides providing structural color for display and sensing, 3DOM materials have been of interest for anticounterfeiting. Here, high complexity has been achieved by preparing Janus-like bilayer 3DOM films with two different pore sizes to achieve different coloration from the front and the back of the film, and by integrating luminescent components, including upconversion nanoparticles . Specific patterns can be inscribed into the polymeric 3DOM films by UV laser irradiation at various stages during the film assembly and processing.…”

Luminescent Color Controller-Based Bilayer PC-UCNPs-PC Dynamically Modulate Photon Propagation

“…In this regard, we reason that the emission color can be tuned along with the variation of PBG directly. To date, remarkable progress has been made in the control of spontaneous emission of light emitters by PCs. − However, there are few reports of dynamic modulation of UCNP emission colors by PCs. Recently, Wu et al prepared PDMS-UCNPs/PS–PDMS PC structure with angle-dependent emission colors .…”

Defect elimination to enhance photoluminescence and optical transparency of Pr-doped ceramics for self-calibrated temperature feedback windows

“…Currently, transparent window materials that can realize temperature feedback mainly include thin films composed of luminescent particles [16,17], Ln-doped glasses or polycrystalline ceramics [13,[18][19][20]. However, conventional thin films and glass mediums suffer from poor physical, chemical, thermal, and optical stability, posing an embarrassment that makes them unsuitable to be served in some harsh cases [21,22].…”