Flexible Perovskite Solar Modules Hit 20.2% at Scale

Researchers led by Soochow University in China have made flexible perovskite solar modules that keep a certified efficiency of 20.2% at a size of 750 square centimetres, and say the modules have passed international stability tests. The work, published in Science this week, also reports a certified 26.9% efficiency for small flexible cells.

Perovskite solar cells printed on plastic film are light and bendable, but they have tended to lose efficiency and stability as they get bigger. The team says it has traced that problem to how a key layer attaches to the plastic, and found a chemical fix. It is a lab and pilot-production result, not a product on sale.

In brief

What happened: A Soochow University-led team reported flexible perovskite solar modules with certified efficiencies of 22.3%, 20.6% and 20.2% as they scaled up to 750 cm², in a peer-reviewed Science paper.
Why it matters: Losing performance at larger sizes has been one of the main barriers keeping flexible perovskite solar in the lab.
What’s next: The university and its industry partner, Suzhou Sunflex New Energy, say they are working towards industrial production.

What the team reported

The Science paper, whose corresponding authors are Soochow professors Yaowen Li and Guiying Xu, gives certified efficiencies for modules on three plastic substrates. Devices with an active area of 14.55 cm² reached 22.3%; 80 cm² devices reached 20.6%; and the largest, 750 cm² on a 1,050 cm² substrate, reached 20.2%.

For small cells, the team reports a certified 26.9%, against a previous best flexible figure of 26.22% cited in the paper. Soochow University’s chemistry faculty says the result sets a new record for flexible perovskite cell efficiency.

Stability is the other half of the claim. The paper says a 22.0% device lost 8% of its starting efficiency after 1,044 hours of continuous operation at 85°C and 65% relative humidity. It also says the modules passed every test sequence in the IEC TS 63163:2021 standard for flexible solar products, certified by the testing body TÜV SÜD.

How the fix works

Flexible perovskite cells are built on plastic film coated with a transparent conductor. A one-molecule-thick layer, known as a self-assembled monolayer, sits between that coating and the light-absorbing perovskite and helps carry charge out of the cell. Making that layer and the perovskite in a single step saves time, but the researchers found that over larger areas the layer does not attach evenly.

According to the Soochow release, the cause is a competition at the surface. Chemical groups on the plastic substrate can bind either to the monolayer molecules or to the solvent, and where they bind to the solvent, the monolayer fails to anchor. “This time, the team focused on exploring at the molecular level how the interface layer forms, and found an exclusive competition mechanism,” Xu told Xinhua (translated).

The team’s answer is an additive it calls BSAI, a “decoupling” molecule that separates those surface groups from the solvent so the monolayer can bind evenly. The university says BSAI also helps control how the perovskite crystals form, improving both the interface and the film on top.

From the lab to a pilot line

The work was carried out with Suzhou Sunflex New Energy, which shares a joint research platform with the university and has staff among the paper’s authors. Li told Xinhua that over the past year the team and Sunflex ran pilot production and made a batch of devices with an effective area of 750 cm², with efficiency stably above 20% and more than double earlier levels.

Soochow University says the commercial-size modules have passed the IEC category II product stability standard and have been used first in portable charging panels and to extend drone flight time. The paper’s authors point to portable and mobile power as likely uses. Soochow has filed a patent application on the method. “We will stick to integrating industry, academia and research, letting real industrial needs drive our research topics, and steadily advance the industrialisation of flexible photovoltaics,” Li said (translated).

Holding efficiency at 750 cm² is a bigger step than the small-cell record

Record efficiencies on tiny cells make headlines, but the more important numbers here are the module results. Perovskite films are typically made from solution, and keeping a film uniform becomes much harder as the area grows. That is why lab records often shrink sharply when a technology moves to panels people can use.

In this paper, efficiency falls from 22.3% to 20.2% as the active area grows more than fiftyfold, from 14.55 cm² to 750 cm². A drop of about two percentage points over that scale-up is modest, and it is backed by independent certification rather than the team’s own measurements. The researchers also tie the gain to a specific mechanism, uneven anchoring of the monolayer, which gives other groups something concrete to test and build on.

The stability results matter for the same reason. Flexible perovskites have struggled with heat and moisture. Passing the full IEC TS 63163 sequence and a 1,044-hour damp-heat run is a meaningful hurdle, although accelerated tests are not the same as years outdoors. The paper does not give a projected lifetime, and that remains the question buyers will ask first.

Light, bendable panels could put solar power where rigid panels cannot go

The applications Soochow names, portable chargers and drones, are telling. They are places where weight and shape matter more than squeezing out every last percentage point, and where conventional glass-covered panels are impractical. A thin film that can follow a curved surface opens up uses on vehicles, tents, backpacks and building surfaces that rigid modules cannot cover.

That fits a wider shift in how clean power reaches people. Big solar farms and grid batteries, such as those now beating gas at Australia’s evening peak, do most of the work, and companies are adding rooftop solar deals like Akamai’s in Singapore. Flexible modules would add generation in places that today have none.

There are open questions. The sources give no cost figures, production volumes or launch dates, and perovskite solar has a long record of promising lab results that took years to reach factories. Solar manufacturing is also becoming a strategic issue: China has proposed adding solar technologies to its export-control catalogue, which could shape where advances like this one are made and sold.

What happens next

Soochow University and Sunflex say they will keep pushing the technology towards industrial production. The next markers to watch are long-term outdoor performance data for the 750 cm² modules, and whether the portable charging panels the university describes move from pilot batches to products with a price.