Photocurrent and dielectric/ferroelectric properties of KNbO3-BaFeO3-δ ferroelectric semiconductors

Perovskite oxide (1-x) KNbO3-xBaFeO(3-delta) (KN-BF; x = 0.00-0.10) ferroelectric semiconductor ceramics are prepared via traditional solid-state synthesis and air sintering. All ceramics show a single perovskite structure and a long-range polarity order by X-ray diffraction (XRD) and Raman spectra, respectively. A minimum optical band gap of approximately 1.82 eV, which is approximately 43% lower than that of pure KN (approximately 3.22 eV), is obtained for the x = 0.10 sample. The ferroelectric behavior of the samples weakens with the increase in BF doping content. The activation energies of the ferroelectric domain and domain wall of 0.93KN-0.07BF ceramics are approximately 0.26 eV and approximately 0.52 eV, respectively, which are ascribed to the conduction mechanism of the first and second ionizations of oxygen, respectively. For the 0.93KN-0.07BF sample, along the positive polarization direction, the short-circuit photocurrent density and open-circuit photovoltage are 11.39 nA cm(-2) and 0.217 V under AM1.5 standard sunlight. The results guarantee the feasibility of applying KN-BF ceramics to ferroelectric photovoltaic devices.