Light to electricity: New multi-material solar cells set new efficiency standard

Researchers from the University of Toronto Engineering and King Abdullah University of Science and Technology (KAUST) have overcome a key obstacle in combining the emerging solar-harvesting technology of perovskites with the commercial gold standard—silicon solar cells. The result is a highly efficient and stable tandem solar cell, one of the best-performing reported to date.

"Adding a layer of perovskite crystals on top of textured silicon to create a tandem solar cell is a great way to enhance its performance," says Yi Hou, postdoctoral fellow and lead author of the new paper. "But the current industry standard is based on wafers—thin sheets of crystalline silicon—that were not designed with this approach in mind." Though they may look smooth, standard silicon wafers used for solar cells feature tiny pyramidal structures about two micrometres high. The uneven surface minimizes the amount of light that reflects off the surface of the silicon and increases overall efficiency, but also makes it difficult to coat a uniform layer of perovskites on top.

Hou and the rest of the team took a different approach. They increased the thickness of the perovskite layer, making it high enough to cover both the peaks and the valleys created by the pyramidal structures. The tandem solar cells achieved an efficiency of 25.7 per cent. This is among the highest efficiencies ever reported for this type of design. They were also stable, withstanding temperatures of up to 85 degrees Celsius for more than 400 hours without a significant loss of performance.

Read more at Phys.org

Image Credit: KAUST

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