Electroabsorption Spectra of the Vanadyl Phthalocyanine Films

Under electric fields close to 10 6 V/ cm several electronic absorptions of the vanadyl phthalocyanine films in the visible and near infrared regions were found to occur with significant electric dipole-moment and polarizability increases, while the rest of the transitions were accompanied by only polarizability increases. The former pointed to the involvement of the charge transfer (CT) excitons, and thus had greater probability of charge-carrier generation as compared with absorptions to the Frenkel exciton states (the latter cases). Additionally, several very weak absorptions were reaffirmed and ascribed to transitions to the CT states. The characterization of phase change in the VOPc films was also illustrated.