RESUMEN
Heterostructures are central to the efficient manipulation of charge carriers, excitons and photons for high-performance semiconductor devices. Although these can be formed by stepwise evaporation of molecular semiconductors, they are a considerable challenge for polymers owing to re-dissolution of the underlying layers. Here we demonstrate a simple and versatile photocrosslinking methodology based on sterically hindered bis(fluorophenyl azide)s. The photocrosslinking efficiency is high and dominated by alkyl side-chain insertion reactions, which do not degrade semiconductor properties. We demonstrate two new back-infiltrated and contiguous interpenetrating donor-acceptor heterostructures for photovoltaic applications that inherently overcome internal recombination losses by ensuring path continuity to give high carrier-collection efficiency. This provides the appropriate morphology for high-efficiency polymer-based photovoltaics. We also demonstrate photopatternable polymer-based field-effect transistors and light-emitting diodes, and highly efficient separate-confinement-heterostructure light-emitting diodes. These results open the way to the general development of high-performance polymer semiconductor heterostructures that have not previously been thought possible.
RESUMEN
We describe in this paper an easy route to the synthesis of a novel surface-functionalized conducting polyaniline-chitosan nanocomposite. A stable colloidal dispersion was prepared when aniline was polymerized in the presence of chitosan as the steric stabilizer. TEM study shows that these surface-functionalized polyaniline-chitosan nanoparticles have rice-grain morphologies. The effect of reaction parameters on the mean size of the polyaniline-chitosan nanoparticles was studied. The steric electrostatic interaction between segments of these two polymers explains the excellent storage stability of the polyaniline-chitosan dispersion. Reaction parameters were optimized in order to get stable polyaniline-chitosan dispersion. The chemical structures of polyaniline-chitosan nanocomposite were characterized. FT-IR spectra of the polyaniline-chitosan nanocomposite show that there exist a certain interaction between polyaniline and chitosan. X-ray photoelectron spectroscopy spectra show that chitosan is largely present at the surface of polyaniline-chitosan nanoparticles. The electrical conductivity of the polyaniline-chitosan nanocomposite increases with increasing the amount of polyaniline to a high value of 0.25 S/cm.