Bio-derived chlorophyll dye doped cholesteric liquid crystal films and microdroplets for advanced anti-counterfeiting security labels

We report the reflection of cholesteric liquid crystal under daylight and chlorophyll fluorescence under UV light. This combination of fluorescent and reflection colors exibhits the features of anticounterfeirting materials in the form of flat inks and microdroplets as well. The working of authenticated/protected QR codes is demonstrated successfully. [Display omitted] •Chlorophyll dye is synthesized from spinach plant leaves emits intense red light under UV light irradiation.•A two-tone system is manifested in which two colors are regulated by two different mechanisms: the color under daylight is governed by the pitch of the cholesteric liquid crystals, although the colour under UV light is still determined by the fluorescent pigments but bio-derived chlorophyll dye.•It exhibits the features of anti-counterfeirting materials in the form of cholesteric flat inks and microdroplets as well.•The functionality of authenticated/protected QR codes has been successfully demonstrated. Herein, we have shown security codes based on an advanced anti-counterfeiting material that are difficult to duplicate and are substantially distinct from the present technology. The anti-counterfeiting material can be made by dispersing green synthesized chlorophyll from spinach leaves into cholesteric liquid crystal (Red, Green and Blue reflections). The resultant anti-counterfeiting material reflects color in daylight (Red/Green/ Blue) due to the reflection property of CLCs and magenta color in UV light due to the fluorescence property of chlorophyll. Furthermore, we have shown that anti-counterfeiting material confined to spherical microdroplets produced by glass capillary microfluidic approach exhibit dual-mode display and security ink properties under daylight and ultraviolet light, including authenticate/non-authenticate QR codes, implying their potential applications in anti-counterfeiting technologies for the protection of valuable objects. These color variations are easily detectable in real time and may be used to create anti-counterfeiting patterns with color changesin both reflection and fluorescence modes. Because of the easy technique, we believe this can give a new platform for numerous security and color-based applications that is more cost-effective and environmentally friendly than traditional approaches.