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

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.