Self-assembly of silver and gold nanoparticles in a metal-free Phthalocyanine liquid crystalline matrix: structural, thermal, electrical and nonlinear optical characterization

Abstract

The properties of self-assembled supramolecular structures change remarkably upon the dispersion of a minute amount of metal nanoparticles in them. Here we present, for the first time, investigations of the effect of dispersing alkyl thiol functionalized group-XI metal nanoparticles (silver and gold) in a phthalocyanine-based discotic liquid crystal on their structural, electrical, thermal and nonlinear optical transmission properties, and supramolecular order. Results indicate uniform dispersion of about 0.5-3 % metal nanoparticles in the columnar matrix which results in an increase of the electrical conductivity of the system by two to four orders of magnitude, without disrupting the mesophase. We also show that dispersing metal nanoparticles in these nanocomposites enhances their nonlinear optical absorption, when measured under excitation by nanosecond laser pulses at 532 nm. These results indicate that the present self-assembling supramolecular soft nanocomposites are potential candidates for applications in optoelectronic devices such as thin film transistors, photovoltaic solar cells, and optical limiters.