Au nanoparticle scaffolds modulating intermolecular interactions among the conjugated azobenzenes chemisorbed on curved surfaces: tuning the kinetics of cis-trans isomerisation.

π-π Intermolecular interactions among adjacent conjugated azobenzenes chemisorbed on (non-)flat Au surfaces can be tuned by varying the curvature of the Au nanoparticles. Here we show that such interactions rule the thermal cis-trans isomerization kinetics, towards a better control on the azobenzene bistability for its optimal integration as a responsive material.

The role of size and coating in Au nanoparticles incorporated into bi-component polymeric thin-film transistors.

We describe the effect of blending poly(3-hexylthiophene) (P3HT) with Au nanoparticles (AuNPs) on the performance of organic thin-film transistors. To this end we have used AuNPs of two different sizes coated with chemisorbed SAMs of oligophenyl-thiols possessing increasing lengths. The electrical characteristics of the hybrid materials revealed changes in the field-effect mobility depending primarily on the AuNP size, as a result of the variable energy level of the coated metallic nanocluster and by the degree of modification of the P3HT crystalline structure.

Optically switchable organic field-effect transistors based on photoresponsive gold nanoparticles blended with poly(3-hexylthiophene).

Interface tailoring represents a route for integrating complex functions in systems and materials. Although it is ubiquitous in biological systems--e.g., in membranes--synthetic attempts have not yet reached the same level of sophistication. Here, we report on the fabrication of an organic field-effect transistor featuring dual-gate response. Alongside the electric control through the gate electrode, we incorporated photoresponsive nanostructures in the polymeric semiconductor via blending, thereby providing optical switching ability to the device. In particular, we mixed poly(3-hexylthiophene) with gold nanoparticles (AuNP) coated with a chemisorbed azobenzene-based self-assembled monolayer, acting as traps for the charges in the device. The light-induced isomerization between the trans and cis states of the azobenzene molecules coating the AuNP induces a variation of the tunneling barrier, which controls the efficiency of the charge trapping/detrapping process within the semiconducting film. Our approach offers unique solutions to digital commuting between optical and electric signals.

Light-responsive reversible solvation and precipitation of gold nanoparticles.

Photo-irradiation with visible and UV light can be used to reversibly trigger the precipitation and solvation, in organic media, of Au nanoparticles coated with a rigid-rod type azobenzene.