Evaluation of Electrical Properties of Merocyanine Films Doped with Acceptor or Donor Molecules by Field Effect Measurements

Koji HIRAGA  Masaaki IIZUKA  Shigekazu KUNIYOSHI  Kazuhiro KUDO  Kuniaki TANAKA  

IEICE TRANSACTIONS on Electronics   Vol.E81-C    No.7    pp.1077-1082
Publication Date: 1998/07/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Organic Materials for Optics and Electronics)
doping,  field effect measurement,  electrical conductivity,  carrier mobility,  carrier concentration,  

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The doping effect of acceptor molecule tetracyanoquinodimethane (TCNQ) and donor molecule tetramethyltetraselenafulvalene (TMTSF) in an organic semiconductor was investigated by field effect measurements in merocyanine (MC) films. The electrical conductivity and carrier concentration of TCNQ-doped MC films were increased compared with those of undoped MC film. An efficient doping effect was observed at the doping concentration of approximately 9%. The electrical conductivity, on the other hand, was decreased by doping of the donor molecule TMTSF in MC film. However, no inversion of the conduction type was obtained. Furthermore, the transport mechanism of TCNQ-doped MC film and undoped film was elucidated from the temperature dependence of electrical parameters. These results demonstrate that TCNQ and TMTSF molecules act as acceptor and donor impurities in MC film, respectively, and the doping of these molecules is effective to control the electrical properties of organic semiconductors.