Thin layers of ET2I3 obtained by in situ crystallization — the role of polymer matrix

Unconventional method of preparation of thin layers of organic crystals by in situ crystallization consists in using a polymer matrix as a reservoir of molecular compounds and also as a medium of crystallization. We discuss an influence of properties of the polymer matrix on the crystallization and properties of the C1-ET2I3 polycrystalline layers, and on their transformation by annealing into the layers of superconducting βt-ET2I3 phase. Polycarbonate, polystyrene and poly(methyl methacrylate) were used as the matrices. The properties and structure of the polycrystalline layers were investigated by means of direct current and microwave conductivity measurements in a broad temperature range, by Raman spectroscopy, AFM and SEM. It was found that in the systems with polymer matrices of lower Tg, the α->βt transformation occurs easier and at lower temperatures, yielding metallically conducting layers which show in some cases an onset of superconducting transition at liquid helium temperatures.