CSIR – National Institute for Interdisciplinary Science and Technology (NIIST)

Council of Scientific & Industrial Research (CSIR), Govt.Of India Thiruvananthapuram.

Nanosheets of Organic Molecular Assembly from Aqueous Medium Exhibit High Solidstate Emission and Anisotropic Charge Carrier Mobility

Samrat Ghosh, Divya Susan Philips, Akinori Saeki and Ayyappanpillai Ajayaghosh, Adv. Mater. 2017, 29, 1605408. Full Text: Link

The past 30 years have seen a quantum leap in the field of supramolecular chemistry ‒ a field that was crafted and moulded in the human hands with the inspiration from Mother Nature. Nature has most of its beautiful assemblies stabilized in water and are highly functional, be it the DNA or the photosystems, both of which sustains life on earth. Thus, water being inexpensive, ubiquitous and environmentally benign, forms the most ideal choice for self‒assembly. In this report, Ajayaghosh and his team report the development of two-dimensional (2D) semiconducting nanosheets by the self- assembly of an organic molecule in water medium. The 2D nanosheet formed is highly fluorescent in the solid state with enhanced charge carrier mobility. The amphiphilic molecule is designed in such a way to have a water loving and water hating side chain, leading to high anisotropic molecular arrangements. They exhibit high solid state fluorescence quantum yield of 0.54 with superior anisotropic charge carrier mobilty of 0.33 cm2/Vs. This value is among the highest reported for various supramolecular assemblies and the observed anisotropy is attributed to the preferential edge-on orientation of the molecule as concluded from the linear dichroism and Grazing Incidence X-ray Diffraction measurements.