Ferroelectric domain walls, so it has been suggested, have properties that might lead to a photovoltaic effect.
We investigated trapping of charge carriers (electrons, holes, and excitons) at ferroelectric domain walls in BiFeO3 through polaron formation from first principles, using density-functional theory. We find small electron and exciton polarons at the domain walls, but only large hole polarons.
When we increase the density of excitons (corresponding to increasing the intensity of light irradiation), we see a transition from a large to a small exciton polaron.
From the charge-carrier density of excitons at the domain walls we estimate the voltage created by ferroelectric domain walls upon light irradiation.