Science: KAUST-led team reports perovskite silicon tandem mini modules that clear key IEC stress tests

A team at King Abdullah University of Science and Technology reported on Thursday in Science that perovskite silicon tandem mini modules maintained performance through standard accelerated aging tests that underpin IEC 61215 certification. The work quantifies how specific interlayers suppress ion migration in the perovskite top cell, addressing a longstanding durability gap as companies move tandems from lab cells to factory lines.

The paper, led by Stefaan De Wolf at KAUST’s Solar Center with collaborators at Helmholtz Zentrum Berlin and the University of Sydney, focuses on reliability rather than a new record efficiency. It arrives as Oxford PV, Longi, and other manufacturers advance tandem pilot lines, and as buyers and financiers increasingly require verified stress test data before making procurement decisions.

What the Science study measured

The researchers built four cell stacks on silicon heterojunction bottom cells and laminated them into roughly 400 square centimeter mini modules. Initial performance was verified by an independent calibration lab, then the modules underwent damp heat at 85 degrees Celsius and 85 percent relative humidity and thermal cycling between minus 40 and 85 degrees Celsius, both part of IEC 61215.

Devices that used an ultrathin nickel oxide hole transport layer, a compact tin oxide electron contact, and a thin alumina diffusion barrier at the tunnel junction retained most of their output after the stress exposure. Time of flight secondary ion mass spectrometry and in situ photoluminescence mapping indicated a lower halide migration signal across the interface stack, consistent with the observed stability.

Why it matters now

The team reports that modules with these interlayers showed smaller drops in fill factor and open circuit voltage after aging than controls that lacked the barriers, a failure mode that has limited perovskite durability. The authors, including Steve Albrecht at Helmholtz Zentrum Berlin and Anita Ho Baillie at the University of Sydney, frame the result as design guidance for module engineers rather than a finished certification.

The work does not demonstrate full IEC 61215 qualification on production scale panels, and outdoor lifetime under ultraviolet exposure and mechanical load still needs to be established. The authors note that encapsulant choice and edge sealing influenced outcomes, which means process control on manufacturing lines will remain decisive.

For manufacturers and policymakers, the data supports near term field trials and early procurement frameworks that include tandems, provided warranty structures reflect remaining uncertainties. It signals that the limiting factor for tandems is shifting from fundamental materials stability to repeatable interface engineering and quality control, which aligns with how other photovoltaic transitions reached scale.