Design and Synthesis of a Variable Filled Band Molecular Conductor

Abstract

New pseudo one-dimensional (1-D) substances are required to understand the salient features associated with unidimensionali-ty. To date a variety of organic (e.g., tetrathiofulvalene (TTF), 7,7,8,8-tetracyano-p-quinodimethane (TCNQ)), inorganic (e.g., K₂Pt(CN)₄Br_0.3·3H₂O(KCP)), and covalent polymers (e.g., poly-(sulfurnitride)(SN)_x) have been studied.¹ However, due to significant differences in the types of bonding, resultant bandwidth, different stoichiometries (Tables I-II), and crystal structures detailed comparisons between these classes of materials are difficult to make. To help clarify the problem we focused our attention at approaching the situation from a different viewpoint, namely, studying the physical properties solely as a function of band filling, i.e., Fermi energy. In contrast with “classical” semiconductors, e.g., silicon, where doping with electron deficient, e.g., gallium, or electron rich, e.g., arsenic, atoms is easily accomplished to vary the Fermi energy, wide variation of the band filling of molecular based materials had not been previously reported.

Table I Prototype 1-D Systems

Table II Representative 1-D Materials