Studies on Molecular Conductors: From Organic Semiconductors to Molecular Metals and Superconductors

The field of molecular conductors was pioneered by works on the semiconducting properties of phthalocyanines and condensed aromatic hydrocarbons in the middle of the last century. Around three decades ago, the first organic superconductor was reported. Since then, various new molecular superconductors based on multichalcogen π molecules such as bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF), dimethyl(ethylenedithio)diselenadithiafulvalene (DMET), BETS (or BEDT-TSF = bis(ethylenedithio)tetraselenafulvalene), and [M(dmit)(2) ] (M = Ni, Pd; dmit = 4,5-dimercapto-1,3-dithiole-2-thione) including unprecedented antiferromagnetic and field-induced organic superconductors and the first single-component molecular metals were developed by the members in the Department of Chemistry of the University of Tokyo along with outside collaborators. Studies on the physical properties--especially optical properties--of various types of molecular conductors are also extensively examined.