| 概 要 |
The main subject of this presentation is Raman spectroscopy of charge transfer complexes (CT) of tetrathiafulvalene (TTF) derivatives: bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) and bis(ethylenethio)tetrathiafulvalene (BET-TTF) in a form of single crystals and also polycrystalline films or layers. Single crystals of the CT complexes were obtained by electrocrystallization, and films or layers were obtained by electrodeposition. The interest in preparation and investigations of thin films arises from the fact, that it is difficult to use the CT complexes as single crystals in the electronic and optoelectronic industry.
Using Raman spectroscopy the frequency of the C=C stretching modes in donor molecules in a series of beta-phase of BET-TTF based CT complexes and salts were characterised. The observed bands were attributed to the C=C stretching modes on the basis of the Density Functional Theory (DFT) calculations. The shift of observed frequency of these modes is approximately linearly dependent on the charge on the BET-TTF donor molecule, which allows establish the correlations between them.
For CT complexes showing the metal-insulator phase transitions the Raman study in the temperatures above and below temperatures of these transitions were performed. In that way the hypothesis, that those phase transitions are caused by the charge ordering were verified.
The morphology of the electrodeposited films and layers strongly depend on the current density used during the electrodeposition. It was found also that the stoichiometries of the CT complexes grown on a silicon electrode are independent on the current density. Potential practical importance may have the electrodeposited layers of TTF[Ni(dmit)2]2, (BEDT-TTF)[Ni(dmit)2]2 and BET-TTF[Ni(dmit)2]2 because these complexes form continuous films covering all the silicon electrode, and also films of the (BEDT-TTF)2PF6 complex showing unidirectional orientation.
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