Perovskite solar cell breaks 30% efficiency barrier, nearing mass production

"31.72% — a new world record efficiency."

South Korean researchers have achieved a breakthrough in the commercialization of next-generation perovskite solar cells.

A research team led by distinguished professor Seok Sang-il at the Ulsan National Institute of Science and Technology (UNIST) has developed, in collaboration with researchers at Saudi Arabia's King Abdullah University of Science and Technology (KAUST), an interfacial coating material needed for the mass production of high-efficiency tandem solar cells. The material enables the fabrication of perovskite-silicon tandem solar cells with efficiencies exceeding 30% through standard manufacturing processes that expose the cells to moisture and oxygen.

A perovskite-silicon tandem solar cell stacks a perovskite cell on top of a silicon cell to achieve ultra-high efficiency. The upper perovskite layer absorbs shorter-wavelength sunlight first, while the lower silicon layer captures the remaining light, yielding higher efficiency than conventional silicon solar cells alone. That combination is expected to open applications well beyond rooftop solar installations — including building facades, windows, car roofs, indoor sensors, wearable devices, and aerospace power systems.

The material the team developed is a thin contact layer deposited on the electrode surface before the perovskite layer is applied. When this layer adheres uniformly, the perovskite solution spread on top distributes evenly as well, reducing the defects through which charge carriers — the electrical particles that generate current — are lost.

Conventional self-assembled monolayer (SAM) coating layers fail to adhere uniformly to electrodes in the presence of atmospheric moisture and are easily disrupted during the perovskite solution coating process. High-efficiency cells therefore had to be fabricated inside specialized equipment that excludes moisture and oxygen, driving up the cost of large-area production.

The team's three-component material adds GDMA and AG to the conventional SAM compound Me-4PACz. GDMA helps the coating layer spread evenly across the electrode and bond firmly after heat treatment, while AG reduces defects at the interface where the coating meets the perovskite layer. Fewer defects mean charge carriers generated by light reach the electrode without being lost along the way, raising both the efficiency and voltage of the solar cell.

The tandem cell incorporating the new material achieved 31.72% efficiency even though it was fabricated in ambient air — a world record for tandem cells produced under such conditions. An independently certified efficiency of 31.36% was also confirmed.

Durability improved markedly as well. Without any protective encapsulation, the cell retained more than 92% of its initial performance after 600 hours in hot air at 85 degrees Celsius, and maintained efficiency above 90% after 1,000 consecutive hours of exposure to intense light simulating real sunlight.

"Commercializing high-efficiency tandem solar cells requires solving not just performance but also reproducibility in actual manufacturing processes and production costs," professor Seok said. "This research demonstrates that a uniform interfacial thin film and high reproducibility can be achieved even in ambient air with moisture present, and it will serve as the technological foundation needed to scale up to large-area manufacturing processes."

The findings were published June 1 in Nature Photonics, an international journal covering optics and photonics.