Significantly enhanced photoelectric/photovoltaic performance in AgNbO₃-based solid-solution ceramics

Anomalous photovoltaic effect of ferroelectrics is receiving intensive research interests. However, many ferroelectric materials struggle to effectively harness the solar spectrum due to their large bandgaps. AgNbO₃ has partial visible-light response, but weak photoelectric/photovoltaic performance. Here, we prepare and report the photoelectric/photovoltaic performance of Ag_1-xK_xNbO₃ solid-solution ceramics. The results indicate that all the investigated ceramics exhibit a narrow bandgap (E_g≈1.95 eV); mechanical polishing further improves light-absorption, enhancing photoelectric response. Composition-driven improvements in photoelectric/photovoltaic performance were observed, which is closely linked to the enhanced ferroelectricity. The poling electric-field effect on photoelectric/photovoltaic performance and ferroelectric properties reveals that the open-circuit voltage (V_oc) and short-circuit current (J_sc) are directly proportional to the remnant polarization until the applied field reaches 100 kV/cm. Upon illuminating the polarization-saturated ferroelectric ceramic (x = 0.07) surface, the maximum V_oc (=8 V) and J_sc (=1μA/cm²) were achieved, which are 10 times and 35 times larger, respectively, than those of AgNbO₃ ceramics.