The electrical conductivities of three organic polyiodide chain complexes, a-cyclodextrin-KI-1,. 4 H,O amylose-iodine and (coumarin),-Kt-J, are observed to be decreased at high pressure upto 80 Kilobars along the direction of iodine chains. The lowering of conductivities a t high pressures and the Arrhenius-type temperature dependences arc explained with disordered semiconductor model. The disordered environment of polyiodide chain which lead to weak or strong localization of the charge carriers is discussed. The charge carriers move by thermally-activated hopping with the energies away from the Fermi energy level.
The electrical resistivities of three organic polyiodide chain complexes, namely a-cyclodextrin-KI-I, s 4 H,O, amylose-iodine, and (coumarin)4-KI-I, are found to increase at high pressures up to 80 kbar. The increase in the resistivities a t high pressures and the Arrhenius-type temperature dependence of resistivities can be explained only with trap limited conduction. The effect of trapping is enhanced a t high pressures. Pressure increases either the density of traps or their depth or both.Es wird gefunden, daO der elektrische Wideistand der drei organischen Polyjodidkettenkomplexe, a-Zyklodextrin-KI-I, .4 H20, Amylose-Jod und (Kumarin),KI-I, mit hohen Driicken bis 80 kbar ansteigt. Der Anstieg des Widerstands bei hohen Driicken und die Temperaturabhangigkeit des Widerstands vom Arrhenius-Typ lassen sich nur mit einer Haftstellen-begrenzten Leitfahigkeit erklaren. Der EinfluB der Haftstellen wird bei hohen Driicken vergroI3ert. Druck erhoht entweder die Haftstellendichte oder ihre Tiefe oder beides.
It is found in this study that four amino acids, namely asparagine, arginine, histidine and
glutamine form two-dimensional conducting systems which are charge transfer
complexes (CTCs) with organic acceptors like TCNQ, TCNE, chloranil, DDQ,
TNF and iodine. It is verified using optical absorption edges that these are 2d
conductors like transition metal dichalcogenides obeying absorption functions
different from 1d and 3d conductors. This 2d nature is related to the network of
intermolecular H-bonding in these complexes, which leads to a global H-bonded
network resulting in the absence of local deformation due to the relaxation of
strain.
The charge transfer complexes of organic donors TTF and TMTSF have been prepared and studied with infrared spectroscopy. The nature of transition has been studied by analyzing features of absorption. TTF-TCNQ was found to be a Peierls semiconductor and not metallic. This shows that the mean field transition temperature is operative in TTF-TCNQ. TMTSF-TCNQ and TMTSF-DDQ showed lesser band gap than that of TTF-TCNQ. TTF-DDQ and TTF-I 2 also showed very small band gap and were more conducting than TTF-TCNQ. The band gaps could be assigned to either the Peierls gap or the pinning gap of charge density waves.
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