Ferroelectric, Photoelectric, and Photovoltaic Performance of Silver Niobate Ceramics

Abstract

Ferroelectrics coupled with solar energy conversion are receiving intensive research interest. However, most ferroelectrics with a large remnant polarization can only harvest ultraviolet light in the solar spectrum. Herein, high-quality silver niobate (AgNbO 3 ) ceramics prepared by spark plasma sintering is reported with a bandgap of ≈2.75 eV and a long tail absorption until 800 nm, leading to outstanding photoelectric properties featured by the visiblelight response over 550 nm. Instantaneous photoresponse measurement using a 355 nm nanosecond pulse laser shows a fast response speed in nanoseconds. Moreover, the ceramic exhibits an intriguing photovoltaic effect under either electric poling or mechanical polishing. Both approaches have switchable characteristics and produce a stable photovoltage as well as photocurrent, while temperature dependence behavior reveals distinctions between ferroelectric polarization and ferroelastic strains in determining the photovoltaic properties. Piezoelectric force microscopy characterization further confirms distinctions between the underlying mechanisms. The electric poling induced photovoltaic effect stems from the aligned polarization involving the ferroelectric component, whereas the mechanical polishing induced photovoltaic effect is associated with the flexoelectricity induced by strain gradients. These results not only show AgNbO 3 to be a promising material for photoelectric application but also deepen the understanding of the mechanism underlying ferroelectric photovoltaics.

Flexophotovoltaic Effect in Potassium Sodium Niobate/Poly(Vinylidene Fluoride‐Trifluoroethylene) Nanocomposite

“…[1] The APV effect widely exists in ferroelectric semiconductor materials, including barium titanate (BTO), [2,3] lead zirconate titanate (PZT), [4,5] and silver niobate (AgNbO 3 ). [6] This phenomenon derives from excited electrons spanning the impurity level to the conduction band due to the interaction between phonons and electrons. In this phenomenon, electrons can be excited by light illumination, resulting in a stable photocurrent in an external circuit.…”

Ferroelectric Materials for Solar Energy Scavenging and Photodetectors

“…A planar ferroelectric device based on AgNbO 3 ceramic with a broad light absorption until 800 nm and a remarkable PV property under visible-light illumination. [38] Figure 4e exhibits the configuration of the prepared device, and the photocurrent enhances the light intensity and the photo-induced signals with a fast response, possessing great potential application of solar scavenging and optical detection. Tao Li and co-workers found that UV irradiation MoS 2 film can make polarization direction initially up polarization direction of BaTiO 3 film down inside, [39] for originally downward BTO film did not affect the polarization direction, light caused internal exciton MoS 2 film production, makes the positive charge accumulation at the interfaces and induced polarization direction from vertical to the vertical downward BTO.…”

“…e) Photoelectric device based on AgNbO 3 ceramics. Reproduced with permission [38]. Copyright 2019, Wiley-VCH.…”

High energy storage density and efficiency with excellent temperature and frequency stabilities under low operating field achieved in Ag0.91Sm0.03NbO3-modified Na0.5Bi0.5TiO3-BaTiO3 ceramics

“…Additionally, Zhao et al also found that lead-free AgNbO 3 ceramics showed a characteristic antiferroelectric double hysteresis loop at a low electric field of 13 kV/mm and a high W rec of 1.6 J/cm 3 at 14 kV/mm was achieved [16]. This finding has triggered a burst of research activities on AgNbO 3 ceramics [54][55][56][57][58][59][60][61][62][63][64]. Among them, Luo et al reported that Ag 0.91 Sm 0.03 NbO 3 (ASN) sample showed excellent energy storage performance (W rec = 5.2 J/cm 3 and η = 68.5%) [64].…”