Jung Il Jin

High‐Temperature Ferromagnetism of a Discotic Liquid Crystal Dilutely Intercalated with Iron(III) Phthalocyanine

Room-temperature ferromagnetism of an organic discotic liquid crystalline compound (DLC) is achieved by intercalation at low levels with paramagnetic iron(III) phthalocyanine (see figure). These ferromagnetic DLCs are very similar to the so-called dilute magnetic semiconductors of inorganic nature. It is expected that this novel approach will open up a new way of preparing the high-temperature organic ferromagnetic compounds needed for molecular spintronics.

p-type doping in organic light emitting diodes based on fluorinated C60

We report on hybrid organic light emitting diodes based on spin coated PVK (poly(vinylcarbazole))/poly-TPD (poly(triphenyldiamine)) formulation electron blocking and conjugated peptide emitter layers while the hole blocking, BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), layer is vacuum sublimed. The device structure is realized through the use of fluorinated C60 as a p-dopant in a cross-linked hole transporting formulation. The lowering of the turn-on voltage is demonstrated using a conjugated peptide as the emitter layer. We suggest that fluorinated C60s could play a major role as tunable dopants in organic electronics.

Reversible polarization gratings on thin films of polyoxetanes bearing 4-(N,N-diphenyl)amino-4′-nitroazobenzene chromophores

Polarization gratings were fabricated by the two-beam coupling method on the surface of a series of polyoxetanes containing 4-(N,N-diphenyl)amino-4′-nitroazobenzene pendants with the azobenzene chromophores either side-on attached or end-on attached through short or long spacers to the main chain. The dynamics of formation of the gratings or writings was studied in relation to the diffraction efficiency. The erasing behavior of the gratings was also examined, irradiating a linearly polarized single beam. The temporal stability of the diffraction efficiency was further studied after removing the coupled excitation beam. Both the mode of attachment of the chromophore to the main chain and the length of the side-chain spacer greatly influenced the dynamic properties of the diffraction gratings. The presence of a long side-chain spacer and side-on attachment of the chromophore resulted in faster writing and erasing behavior. A preliminary study by solid-state 13C NMR of the relaxational behavior of the main-chain CH2 groups and the pendant chromophores provided a reasonable picture to help explain the photo-induced reorientation and relaxation of the azo chromophores at the molecular level.