We have studied the electronic structure of potassium-doped copper phthalocyanine (CuPc) using photoemission spectroscopy. A detailed analysis of the core-level spectra allows us to propose possible lattice sites for the potassium ions. None of the films prepared in our studies showed a finite electronic density of states at the Fermi level (EF), which is in contrast to reports in the literature. Possible reasons for this discrepancy are discussed.

The chemistry and electronic structure of the interface between indium metal deposited onto thin films of CuPc ͑copper phthalocyanine͒ have been studied as a function of indium deposition using valence band ͑VB͒ and core level ͑CL͒ photoemission spectroscopy ͑PE͒. Two stages of the In/ CuPc interface formation upon In deposition have been observed. The first stage is characterized by a strong diffusion of the In atoms into the organic film. Metal ions occupy sites close to the pyrolle nitrogens of CuPc and strongly interact with molecules transferring negative charge. Indium diffusion into the organic films stops at a stoichiometry of In 2 CuPc. Subsequently, in the second stage the formation of a metallic indium film occurs on the top of the In 2 CuPc film.

A discrete phenomenological model of antiferroelectric liquid crystals is used to study the structures and phase transitions in bulk samples and thin films. An important ingredient of our investigations is minimization of the free energy with respect to the phase and modulus of the order parameter. A simple version of the free energy, which contains only the nearest-neighbor and the next-nearest-neighbor layer interactions gives a complete phase diagram with all the observed smectic-C* (SmC*) variant phases. In thin free-standing films, surface ordering may lead to suppression of the bulk SmC(*)(alpha) helix and to formation of planar structures. Transitions between these structures are accompanied by the 90 degrees reorientation of the polarization direction. We also discuss the influence of chirality on subphase structures.

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