02262nas a2200433 4500008004100000022001300041245007600054210006900130490000800199520097200207653001401179653002101193653002301214653001701237653002401254653002901278653002601307653002801333653002101361653003201382653001501414653001801429653002001447653003101467653002401498653002401522653001801546653002601564653002501590653002301615100001501638700001101653700001601664700002401680700001101704700002401715700001501739856007401754 2011 eng d a0031900700aEfficient photovoltaic current generation at ferroelectric domain walls0 aEfficient photovoltaic current generation at ferroelectric domai0 v1073 aWe elucidate the mechanism of a newly observed photovoltaic effect which occurs in ferroelectrics with periodic domain structures. Under sufficiently strong illumination, domain walls function as nanoscale generators of the photovoltaic current. The steps in the electrostatic potential function to accumulate electrons and holes on opposite sides of the walls while locally reducing the concentration of the oppositely charged carriers. As a result, the recombination rate adjacent to the walls is reduced, leading to a net diffusion current. In open circuit, photovoltages for periodically ordered domain walls are additive and voltages much larger than the band gap can be generated. The internal quantum efficiency for individual domain walls can be surprisingly high, approaching 10% for above band-gap photons. Although we have found the effect in BiFeO3 films, it should occur in any system with a similar periodic potential. © 2011 American Physical Society.10aBand gaps10aCharged carriers10aDiffusion currents10aDomain walls10aElectrons and holes10aElectrostatic potentials10aFerroelectric domains10aFerroelectric materials10aferroelectricity10aInternal quantum efficiency10aNano scale10aOpen circuits10aOrdered domains10aPeriodic domain structures10aPeriodic potentials10aPeriodic structures10aPhotovoltages10aPhotovoltaic currents10aPhotovoltaic effects10aRecombination rate1 aSeidel, J.1 aFu, D.1 aYang, S.-Y.1 aAlarcón-Lladó, E.1 aWu, J.1 aRamesh, Ramamoorthy1 aAger, J.W. uhttps://rameshlab.lbl.gov/publications/efficient-photovoltaic-current