Current-Induced Low-Resistance State and Its Crystal Structure of a TTF-Based Dimeric Donor Salt

Abstract

A bromide salt of a TTF-based cross-cyclophane-type donor displayed characteristic nonlinear voltage-biased conductivity. As the applied voltage was increased, the passing current was enhanced abruptly at 54 kV.cm-1, exhibiting hysteretic behavior. X-ray analysis of the current-induced low-resistance state of the crystal, which has P41 symmetry, revealed that the degree of charge disproportionation of the dimeric donor in the crystal substantially decreased during the current application. This result is interpreted as indicating that the class I mixed-valence state of the cation-radical salt of the dimeric donor was converted into the class III state by the application of the large current.

A Mechanism of DC-AC Conversion in the Organic Thyristor

“…After this discovery, the nonlinear conduction in organic conductors has received a renewed attention [5,6,7], although many of organic materials were recognized for non-ohmic conductors long before. [8,9,10,11,12,13] The current oscillation has been also searched and discovered in various strongly correlated systems [14,15]. …”

Molecular-based light-activated thyristor

“…14 In the current-voltage ͑I-V͒ characteristics, field-induced switching effects have been discovered recently in several molecular conductors. 5,[15][16][17] The fieldinduced switching effect can, in general, be attributed to the differential-negative-resistance ͑DNR͒ effect in the I-V characteristic curve of materials. 18,19 The structural change upon the switching has been investigated for a few molecular conductors using x-ray crystallographic methods.…”

“…18,19 The structural change upon the switching has been investigated for a few molecular conductors using x-ray crystallographic methods. 16,20 These studies have shown that the relaxation of charge ordering or disproportion of electrons takes place in a high conductivity ͑HC͒ state in the materials showing the DNR effect.…”

Low‐Field Negative‐Resistance Effect in a Charge‐Ordered State of Thiazyl‐Radical Crystals

“…[2] In fact, current-voltage characteristics of organic materials have been studied extensively, and nonlinear electrical transport phenomena, such as a switching effect with a so-called negative-(differential)-resistance effect, have been already discovered as a characteristic feature of organic semiconductors. [3][4][5][6][7] However, these effects were found to occur at low temperature in a high electric field, in an insulating state caused by charge ordering, neutral-ionic transition, and on-site Coulomb repulsion (Mott-Hubbard insulator). Thus, it is very important to develop organic materials that exhibit this nonlinear behavior under mild conditions.…”

“…In addition, the E T value obtained for [NT] 3 [GaCl 4 ] is much lower than those of the other organic materials that show nonlinear conductivity. [3][4][5][6][7] Lowering the temperature from 290 K, the values of E T and J T exhibit a significant increase and decrease, respectively, making the negative-resistance effect more drastic.…”