Understanding the regulatory factors of self-assembly processes is a necessity in order to modulate the nano-structures and their properties. Here, the self-assembly mechanism of a peptide-perylenediimide (P-1) conjugate in mixed solvent systems of THF/water is studied and the semiconducting properties are correlated with the morphology. In THF, right handed helical fibers are formed while in 10% THF-water, the morphology changes to nano-rings along with a switch in the helicity to left-handed orientation. Experimental results combined with DFT calculations reveal the critical role of thermodynamic and kinetic factors to control these differential self-assembly processes. In THF, P-1 forms right handed helical fibers in a kinetically controlled fashion. In case of 10% THF-water, the initial nucleation of the aggregate is controlled kinetically. Due to differential solubility of the molecule in these two solvents, elongation of the nuclei into fibers is restricted after a critical length leading to the formation of nano-rings which is governed by the thermodynamics. The helical fibers show superior semi-conducting property to the nano-rings as confirmed by conducting-AFM and conventional I-V characteristics.

Novel carbon quantum dots (CQDs) with unexplored potential, are interesting nanomaterials for electronic investigations. Formation of surface defect sites in these Q-dots is a consequence of combinations of various carbon hybridizations. In this work nanocomposites of CQDs with an electronically inert polymer, poly vinyl alcohol (PVA), have been electrically characterized. The electronic properties were observed to be tunable by compositions of component materials. A detail conduction mechanism of charge storage within composites' layer has been worked out. The dielectric properties of composites are observed to be dependent on morphologies developed from segregation of CQDs within composites. The composites possess improved dielectric properties compared to individual component materials. Simulation of the dielectric properties reveals that the nanocomposites actually derive qualities of its' component materials.

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The dispersion behavior of chemically modified reduced graphene oxide (CRGO) has been investigated in five different solvents. Herein, we used cationic surfactant CTAB as a dispersing agent to prevent the agglomeration of graphene layers. The main role of the surfactant is to create dangling bonds on graphene layers and those help to exfoliate. In the physical process, ultra-sonication is used to break the π bonds whereas, in the chemical process, surfactant molecules occupy the space between the graphene layers. The dispersion behavior of CRGO in different liquid media has been observed for over a month. The chemically reduced graphene oxide was characterized by Transmission electron microscopy (TEM) analysis and current-voltage (I-V) measurement.