Transient/persistent switching of Cu-DCNQI by light and pressure

In Cu(2,5-DMe-DCNQI)2 (DCNQI: N,N′-Dicyanoquinonediimine) crystals with metal-like conductivity, phase transitions to an insulating state can be induced by deuteration (internal pressure) and external pressure. A reentry to the metallic state at lower temperature is observed in alloyed Cu-DCNQI systems. R-silence during metallic conductivity is lifted in the insulating state. The correlation of ESR and conductivity allows a quantitative detection of the gradual onset of the phase transition. Because of large hysteresis effects of σ- and ESR-measurements, switching by light and pressure is possible. These features point to prospective application for molecular electronic devices as cystalline (2,5-DMe-DCNQI)2Cu films represent, due to the crystal structure, conducting networks in molecular dimensions switchable from a 3-d to an 1-d conductivity behaviour. This might be realized spatially resolved in nanostructures if electron beam lithography is applied.