Characteristics of rectifying devices with thin films of polyphthalocyanine

Chemically and thermally stable thin films of polyphthalocyanine were prepared by a simple evaporation‐polymerization method. The rectifying characteristics of metal/semiconductor/metal (MSM) type sandwich devices with the film were studied. A Schottky type device metal (Cu, Al, Ti)/polyphthalocyanine/Cu shows reproducible rectifying characteristics when Ti is selected as a counter electrode. The reproducibility is improved by pre‐oxidation treatment of the surface of Cu substrate. Best electric parameters for the device are as follows: rectifying ratio = 14; threshold potential difference = 0,61 V; saturation current = 2,5 · 10−6 A · cm−2; barrier height = 0,75 eV; diode ideality parameter = 4,23. Doping of five kinds of quinones [p‐benzoquinone (p‐BQ), tetrabromo‐p‐benzoquinone (p‐TBBQ) tetrachloro‐p‐benzoquinone (p‐TCBQ) tetrachloro‐o‐benzoquinone (o‐TCBQ) 2,3‐dichloro‐5,6‐dicyanobenzoquinone (DDQ)] and 2,5‐cyclohexadien‐1,4‐diylidenedimalodinitrile (TNCR) in thin films of polyphthalocyanine affected electrocharacteristics in some cases. The diode ideality parameter decreases to 2,17 at 0,90 · 10−6 mol · cm−1 of p‐TBBQ, and the rectifying ratio increases to about fourteen times by doping p‐TBBQ and p‐TCBQ. The doped device shows a rectifying response up to 1 kHz.