Photoluminescence Tuning in Stretchable PDMS Film Grafted Doped Core/Multishell Quantum Dots for Anticounterfeiting

The development of new luminescent materials for anticounterfeiting is of great importance, owing to their unique physical, chemical, and optical properties. The authors report the use of color-tunable colloidal CdS/ZnS/ZnS:Mn²⁺/ZnS core/multishell quantum dots (QDs)-functionalized luminescent polydimethylsiloxane film (LPF) for anticounterfeiting applications. Both luminescent QDs and as-fabricated, stretchable, and transparent LPF show blue and orange emission simultaneously, which are ascribed to CdS band-edge emission and the ⁴T₁ → ⁶A₁ transition of Mn²⁺, respectively; their emission intensity ratios are dependent on the power-density of a single-wavelength excitation source. Additionally, photoluminescence tuning of CdS/ZnS/ZnS:Mn²⁺/ZnS QDs in hexane or embedded in LPF can also be realized under fixed excitation power due to a resonance energy transfer effect. Tunable photoluminescence of these flexible LPF grafted doped core/shell QDs can be finely controlled and easily realized, depending on outer excitation power and intrinsic QD concentration, which is intriguing and inspires the fabrication of many novel applications.