Photoinduced ferroelectric hysteresis curve in organic CuPc photoconductor/inorganic BaTiO3 ferroelectric heterojunction photomemory

Photoinduced switching of the ferroelectric $\mathrm{P–E}$ hysteresis curve has been achieved in organic photoconductor (PC) copper phthalocyanine (CuPc)/inorganic ferroelectric (FE) ${\mathrm{BaTiO}}_3$ (BTO) heterojunction photomemory in the visible ray region. Light irradiation could switch the remanent polarization of ferroelectric BTO in this heterojunction up to 3 μC/cm², almost full remanent polarization of BTO single layer, whereas remanent polarization of that without light irradiation was almost zero. We have also investigated the effect of CuPc thickness on the photoinduced change of ferroelectric $\mathrm{P–E}$ hysteresis curve, and found that the insulating dark resistance of the organic photoconductor CuPc film layer plays an important role for high efficiency of PC/FE heterojunction photomemory. The efficiency of this heterojunction photomemory reached up to 500%.