HZB Team Reports 27.3% Efficiency for Triple-Junction Perovskite Solar Cell

Researchers at Berlin's HZB have built an all-perovskite triple-junction solar cell that reaches 27.3% efficiency and holds up for a record 770 hours, aided by a new graphene-oxide hole-conducting layer.

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Scientists at the Helmholtz-Zentrum Berlin (HZB) say they have built a triple-junction solar cell assembled from several different perovskite semiconductors, reporting a power-conversion efficiency of 27.3%.

According to the group, the same device also maintained its output for 770 hours of operation, a figure described as a record for cells of this kind.

The central advance, the researchers explain, sits in the layer that moves positive charges through the cell. The team paired graphene oxide (GO) with a self-assembled monolayer (SAM), stacking the two into a single bilayer that acts as the hole conductor. That combination, they report, lifted both the cell's efficiency and its ability to keep working over extended periods.

The appeal of perovskite materials, the team notes, comes from how well they turn incoming sunlight into electricity, together with their low production cost and very light weight. Those traits have made the material class a focus of solar research, even as questions about durability have shadowed earlier designs.

By layering three perovskite absorbers with distinct properties, the triple-junction approach aims to harvest a wider slice of the solar spectrum than a single-layer cell. The HZB results were published on July 9, 2026.