Berkeley Lab Uncovers New Way to Boost PV Cell Efficiency

Scientists from the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have developed a way to use optical microscopy to map thin-film solar cells in 3-D as they absorb photons.

Next-generation solar cells made of super-thin films of semiconducting material have immense potential because they’re reasonably inexpensive and flexible enough to be applied in a variety of formats.

Researchers are trying to find ways to radically increase the efficiency at which thin-film solar cells convert sunlight to electricity despite the challenges of a solar cell’s subsurface realm—where much of the energy-conversion action happens—is inaccessible to real-time, nondestructive imaging. It been seemingly impossible to view improve processes that are unable to be seen.

The method, reported in the journal Advanced Materials, was developed at the Molecular Foundry, a DOE Office of Science user facility located at Berkeley Lab. It images optoelectronic dynamics in materials at the micron scale, or much thinner than the diameter of a human hair. This is small enough to see individual grain boundaries, substrate interfaces, and other internal obstacles that can trap excited electrons and prevent them from reaching an electrode, which saps a solar cell’s efficiency.

“To make big gains in photovoltaic efficiency, we need to see what’s happening throughout a working photovoltaic material at the micron scale, both on the surface and below, and our new approach allows us to do that,” says Edward Barnard, a principal scientific engineering associate at the Molecular Foundry. He led the effort with James Schuck, the director of the Imaging and Manipulation of Nanostructures facility at the Molecular Foundry.

To learn more about the processes the scientists took to find this new breakthrough, please click here.