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Photovoltaic effect in ferroelectrics can be considered as a sum of two dominant contributions, that is, arising from the ferroelectric/metal junctions and from the bulk of the ferroelectrics. In the case of Pb-(Zr0.2Ti0.8)-O3, several studies have been devoted to analyze the contributions from the junctions and associated aspects such as barrier height. In this work, we elaborate on the contribution from the bulk, and the role of an inherent nano-sized entity, that is, domain walls. Systematic investigations were conducted with samples of different thicknesses (75–700 nm), which evidently also assisted in varying the proportion of domain walls. The open-circuit voltages scaled up with thickness in accordance with the bulk-driven photovoltaics phenomenology. Temperature-resolved measurements highlighted the influence of domain walls on the overall transport characteristics under light and dark conditions. Analysis of the spectral photoresponse unraveled the sub-band gap character of the domain walls and the prospective role in the overall photovoltaic effect. [ABSTRACT FROM AUTHOR]

Defect or intermediate states within the band gap of ferroelectric oxides are known to impact functional characteristics such as saturated polarization. However, depending upon their respective position, such levels can also induce a substantial photoelectrical response under appropriate illumination and severely impact the conduction mechanism of an otherwise highly insulating material system. Sub‐band‐gap illumination is used to highlight the activity of these levels in epitaxially grown and ferroelectric Pb(Zr0.2Ti0.8)O3 thin films. Large transient effects are observed in relation to ferroelectric polarization and conductivity after illumination. In the case of polarization, light induces a "leaky" character, which eventually decays over a period of nearly 1.5 h. In conjunction, persistent photoconductivity is observed as the enhanced conductivity attained under illumination gradually decays over several minutes after removal of illumination. Thermally stimulated currents are measured to probe the presence of sub‐band gap states and analyze their effect over a wide range of temperature. The trapping nature of the states and their role in the conduction is found to be the underlying origin. [ABSTRACT FROM AUTHOR]

Absence of inversion symmetry is the underlying origin of ferroelectricity, piezoelectricity, and the bulk photovoltaic (BPV) effect, as a result of which they are inextricably linked. However, till now, only the piezoelectric effects (inverse) have been commonly utilized for probing ferroelectric characteristics such as domain arrangements and resultant polarization orientation. The bulk photovoltaic effect, despite sharing same relation with the symmetry as piezoelectricity, has been mostly perceived as an outcome of ferroelectricity and not as a possible analytical method. In this work, we investigate the development of BPV characteristics, i.e. amplitude and angular dependency of short-circuit current, as the ferroelastic domain arrangement is varied by applying electric fields in planar devices of BiFeO3 films. A rather sensitive co-dependency was observed from measurements on sample with ordered and disordered domain arrangements. Analysis of the photovoltaic response manifested in a mathematical model to estimate the proportion of switched and un-switched regions. The results unravel the potential utility of BPV effect to trace the orientation of the polarization vectors (direction and amplitude) in areas much larger than that can be accommodated in probe-based techniques. [ABSTRACT FROM AUTHOR]