Charge Conduction Properties at the Contact Interface between (Phthalocyaninato)nickel(II) and Electron Acceptor Single Crystals

Single-component crystals of both (phthalocyaninato)nickel(II) (Ni( Pc )) and 2,5-difluoro-7,7,8,8-tetracyanoquinodimethane (F 2 TCNQ) are typical band insulators. However, the contact interface between them demonstrates metal-like transport properties. Although Ni( Pc ) and F 2 TCNQ are an electron donor and an acceptor, respectively, the combination of these two components does not yield any charge transfer (CT) complex crystals. Infrared spectra show that the highly conductive feature originates from charge injection at the contact interface. The thermoelectric power of the mixed powder reveals that the transport at the contact interface is dominated by the holes in the Ni( Pc ) crystal.