Biomedical subjects

Michele Muccini

Publications and source records attributed to Michele Muccini.

3 recordsLinked to original sources

PubMed2006

J-aggregation in alpha-sexithiophene submonolayer films on silicon dioxide.

We report on the observation of J-aggregates in submonolayer films of alpha-sexithiophene grown on silicon dioxide. Photoluminescence spectroscopy reveals that submonolayers are formed by molecules lying flat on the substrate with a head to tail configuration. Excitation energy dependence of photoluminescence shows a red-shifted absorption with respect to isolated molecules and a negligible Stokes shift between absorption and emission. The pronounced structural order of J-aggregates is reflected in the fwhm of the emission bands. From time-resolved and low-temperature photoluminescence experiments, we infer a quantum yield of the J-aggregate between 0.6 and 1. The demonstration of spontaneous formation of J-aggregates of pi-conjugated systems on amorphous silicon-based substrates can be relevant for the development of organic-inorganic hybrid photonic devices.

Journal Article↗

PubMed2006

Effects of surface chemical composition on the early growth stages of alpha-sexithienyl films on silicon oxide substrates.

In organic field effect transistors, charge transport is confined to a narrow region next to the organic/dielectric interface. It is thus extremely important to determine the morphology and the molecular arrangement of the organic films at their early growth stages. On a substrate of technological interest, such as thermally grown silicon oxide, it has been recently found that alpha-sexithienyl aggregates made of flat-lying molecules can simultaneously nucleate besides islands made of molecules standing vertical. In this paper, we investigate the effects due to variations in surface chemical composition on alpha-sexithienyl ultrathin film formation. Flat-lying molecules are no longer detected when Si-OH groups present at the surface are chemically removed but also when the Si-OH or Si-H group density is maximized. This gives evidence that variations in the surface chemical composition can largely affect the nucleation and growth processes of organic/dielectric interfaces. We hypothesize that isolated OH groups can interact with alpha-sexithienyl molecules and anchor them down flat with respect to the surface.

Journal Article↗

PubMed2006

A bright future for organic field-effect transistors.

Field-effect transistors are emerging as useful device structures for efficient light generation from a variety of materials, including inorganic semiconductors, carbon nanotubes and organic thin films. In particular, organic light-emitting field-effect transistors are a new class of electro-optical devices that could provide a novel architecture to address open questions concerning charge-carrier recombination and light emission in organic materials. These devices have potential applications in optical communication systems, advanced display technology, solid-state lighting and electrically pumped organic lasers. Here, recent advances and future prospects of light-emitting field-effect transistors are explored, with particular emphasis on organic semiconductors and the role played by the material properties, device features and the active layer structure in determining the device performances.

Journal Article↗