By changing the polarization direction of bismuth ferrite, these domain walls give rise to a photovoltaic effect. (Credit: Seidel, et. al.)
According to a Lawrence Berkeley National Laboratory press release, researchers have discovered a new path to convert sunlight to electricity. Researchers have found a new mechanism by which the photovoltaic effect can take place in semiconductor thin films. This new route to energy production overcomes the bandgap voltage limitation that continues to be detrimental to conventional solid-state solar cells.
Working with bismuth ferrite, researchers discovered that the application of an electric field makes it possible to manipulate the crystal structure and control the photovoltaic properties.
Working through LBNL’s Helios Solar Energy Research Center, Jan Seidel, a physicist who holds joint appointments with Berkeley Lab’s Materials Sciences Division and the UC Berkeley physics department, and his team discovered that by applying white light to bismuth ferrite they could generate photovoltages within submicroscopic areas between one and two nanometers across. These photovoltages were significantly higher than bismuth ferrite’s electronic bandgap.
At the domain walls, the polarization direction of the bismuth ferrite changes and the photovoltaic effect arises.
“While we have not yet demonstrated these possible new applications and devices, we believe that our research will stimulate concepts and thoughts that are based on this new direction for the photovoltaic effect,” Seidel says.