PHOTOGENERATION MECHANISM OF CHARGED CARRIERS IN COPPER-PHTHALOCYANINE THIN-FILMS

The photogeneration properties of copper-phthalocyanine (CuPc) thin films were investigated by measuring photo-induced displacement currents for metal/CuPc/SiO2/Si devices. The impurity effect that the quantum efficiency (QE) of photogeneration in the layer including impurities is larger than that in the intrinsic layer was quantitatively estimated from this method. The QE increase has been found to be due to the charge transfer reaction from an electron-hole pair generated by photon absorption to an impurity. The QE difference between two layers is discussed in relation to the formation process of bound pairs of opposite charges.