Microscopic Insight into Structure Determination of Ferroelectric Photovoltaics in Aurivillius-Phase Ferroelectrics

Recently, a high open-circuit voltage of the ferroelectricphotovoltaiceffect driven by the polar order of the ferroelectrics has been intensivelyreported in the Aurivillius-phase perovskite structure. However, thefactors limiting the ferroelectric photovoltaic effect are not clearlyunderstood. Here, we observed a correlation between the polar phasefraction and ferroelectric photovoltage in Sr1-x Ba x Bi4Ti4O15 polycrystalline films, where the output intensitywas regulated by the change in the phase fraction parameter & xi;(I4(1) am/A2(1) am tetragonal-orthogonal phase),and lattice distortion was caused by the different dopant concentrationsin the range of (x = 0, 0.2, 0.5, 0.8, and 1.0).The ferroelectric photovoltaic effect is outstanding in the SrBi4Ti4O15 films, which confirms that thepolar phase fraction plays a crucial role in the photocurrent intensity.The photovoltaic external efficiency can reach 28% at the spectrumresponse peak of 340 nm, and we also constructed a function relationto describe the intensity. These results indicate that the ferroelectricpolarization and bandgap are significantly related to the phase fractionevolution. Further, our experimental results not only confirm thespeculated mechanism of enhanced electron-hole separation inferroelectrics but also clarify the unsymmetrical dispersion of photoelectronsas a key factor, which offers an opportunity to understand its nature.

Automated summary

Recently, researchers have emphasized the high open-circuit voltage of the ferroelectric photovoltaic effect in the Aurivillius-phase perovskite structure. However, the factors limiting this effect are not well understood. By investigating the correlation between polar phase fraction and ferroelectric photovoltage in Sr1-x Ba x Bi4Ti4O15 polycrystalline films, it has been found that the polar phase fraction plays a crucial role in the photocurrent intensity. At the spectrum response peak of 340 nm, the photovoltaic external efficiency can reach 28%.