Micro-/Nanotechnology - Optics

Seeing in the Dark: Supramolecular Nanocomposite Optical Filter

A nanocomposite possessing high NIR-transparency is developed, and shown to be applicable for NIR photography, security, and forensic-related applications.

Researchers develop a novel nanocomposite that possesses high near-infrared (NIR)-transparency, and exhibits good thermal- and photostability for practical applications.

Night vision photography, security imaging, and forensic applications all require visibly opaque, NIR-transparent materials. Molecular gel chemistry is at the forefront in development of novel soft materials for organic electronic and solar energy conversion applications.

Schematic illustration of the preparation of NIR transmitting filter. More information here.

In the pursuit of self-assembled materials applicable for such image-based applications much progress has been made; however, the need for better results is immense. Molecular assemblies and organogels have begun to solicit research focus, motivated by the desire to push the boundaries of soft materials research.

In a recent Advanced Materials Communication, by Ayyappanpillai Ajayaghosh and co-workers, a self-assembled black gel from a π-conjugated D–A molecule based on a diketopyrrolopyrrole (DPP) chromophore is developed. The DPP core offers broad absorption in the visible region, and has the ability to form both H- and J-type aggregates in the solid state, therefore potentially broadening the range to the visible region.

The applicability of the gel was tested by modifying a standard digital camera. The NIR reflecting filter was replaced with a DPP-composite filter. The spectral response was measured, and shown to be responsive to NIR light, which is important for applications in security and forensic science.

In conclusion, this novel black organogelator is applicable for optical filter applications, providing a foundation for other supermolecular gelators to be developed for a range of applications.

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