The Photoelectric Properties Of The PZT/Ag₂O-NPs/PZT Composite Films

The photovoltaic effect of ferroelectric thin films has become a worldwide researchfocus recently. Pb（Zrx,Ti1-x）O₃（PZT）, one of the most popular ferroelectric material, with aforbidden bandgap of3.5eV, can only generate a photocurrent by UV light of wavelengthshorter than354nm, and experiences a small photovoltaic efficiency of about0.005%. Inthe present work, we demonstrate a new concept in which the photocurrent effect in PZTferroelectric thin film is enhanced by way of the incorporation of Ag₂O nano-particles（Ag₂O-NPs） that possess a narrow energy gap so as to absorb more energy from the visiblelight spectrum.A serial of PZT/Ag₂O-NPs/PZT compound films were fabricated on the Pt/Ti/SiO₂/Sisubstrate or ITO glass by the RF magnetron sputtering method. The phase structure,surface morphology and optical absorption characteristic were characterized by XRD,AFM, SEM, XPS and UV-VIS spectrum, respectively. The ferroelectric and photoelectricproperties of the composite films were also researched.Experiment result showed that the photoelectric properties of the PZT/Ag₂O-NPs/PZTcompound films not only have certain corresponding relationship with the ferroelectricpolarization field, but also with the size distribution and area density of Ag₂O-NPs. Itindicates that inserting Ag₂O-NPs into the PZT films can effectively improve thephotocurrent under the premise of PZT has enough large rest polarization （Pr）. Thephysical picture explaining the experimental data is quite clear：the narrow bandgapAg₂O-NPs as effective optical absorbing materials, it can produce more photo-inducedcarriers；PZT provides the internal polarization electric field, which can effectivelyseparate and transport photo-induced carriers, so as to output the increased photocurrent.This work sheds light on a new approach to enhance light-electricity conversionefficiency by means of single phase ferroelectric photovoltaic materials, which havepotential for use in both novel optoelectronic and solar energy devices encompassing the UV to visible light spectra.