MODULATED PHOTOCURRENT OF EVAPORATED COPPER PHTHALOCYANINE THIN-FILMS

The photoelectrical behavior of evaporated copper phthalocyanine (CuPc ) thin film sandwich-type and coplanar-type cell were investigated usi ng a modulated photocurrent measurement technique. The modulated photo current sandwich-type cell showed a minimum value at the equilibrium p oint of photovoltage and applied voltage, and a phase shift of the mod ulated photocurrent showed a drastic change of 180 degrees in the vici nity of this point. As for the crystalline growth and decreasing the g rain boundary, the amplitude of the modulated photocurrent increased w ith the increase of substrate temperature at deposition times. A varyi ng point of the phase shift in the long wavelength region of the copla nar-type cell is considered corresponding to the energy band gap of th e CuPc, of which value is determined to be 1.65 eV. (C) 1998 Elsevier Science S.A. All rights reserved.