A new photovoltaic mechanism has been discovered in ferroelectric materials, specifically in bismuth ferrite (BFO). Unlike conventional photovoltaic devices, which rely on the bandgap of the semiconductor to generate voltage, this mechanism operates at nanoscale ferroelectric domain walls, producing voltages significantly higher than the bandgap. The photovoltaic effect is driven by the built-in electric fields at these domain walls, which are created by the polarization of the material. These domain walls, which are 1-2 nm wide, allow for efficient charge separation and generate a large open-circuit voltage (VOC) when illuminated. The voltage can be controlled by electric fields, which can reverse the polarity or turn off the photovoltaic effect. This new mechanism offers a promising avenue for optoelectronic devices with high voltage output. The study demonstrates that the photovoltaic effect in BFO arises from the unique structural properties of the material, with the domain walls playing a crucial role in charge separation. The results show that the photovoltaic response is highly dependent on the domain structure, and that the direction of the current is parallel to the net in-plane polarization. The findings suggest that the photovoltaic effect in BFO is not a bulk property but rather a result of the nanoscale domain walls. The study also shows that the photovoltaic effect can be controlled by electric fields, which can switch the domain structure and thus the photovoltaic response. This control over the photovoltaic effect opens up new possibilities for applications in optoelectronics and photovoltaics.A new photovoltaic mechanism has been discovered in ferroelectric materials, specifically in bismuth ferrite (BFO). Unlike conventional photovoltaic devices, which rely on the bandgap of the semiconductor to generate voltage, this mechanism operates at nanoscale ferroelectric domain walls, producing voltages significantly higher than the bandgap. The photovoltaic effect is driven by the built-in electric fields at these domain walls, which are created by the polarization of the material. These domain walls, which are 1-2 nm wide, allow for efficient charge separation and generate a large open-circuit voltage (VOC) when illuminated. The voltage can be controlled by electric fields, which can reverse the polarity or turn off the photovoltaic effect. This new mechanism offers a promising avenue for optoelectronic devices with high voltage output. The study demonstrates that the photovoltaic effect in BFO arises from the unique structural properties of the material, with the domain walls playing a crucial role in charge separation. The results show that the photovoltaic response is highly dependent on the domain structure, and that the direction of the current is parallel to the net in-plane polarization. The findings suggest that the photovoltaic effect in BFO is not a bulk property but rather a result of the nanoscale domain walls. The study also shows that the photovoltaic effect can be controlled by electric fields, which can switch the domain structure and thus the photovoltaic response. This control over the photovoltaic effect opens up new possibilities for applications in optoelectronics and photovoltaics.