Chinese scientists set world record for solar cell efficiency

Chinese scientists have set a new world record for next-generation solar cells, bringing lightweight, flexible and highly efficient solar power closer to everyday use on everything from wearable devices to space stations.

The researchers achieved a certified steady-state power conversion efficiency of 28.04 percent using a perovskite-organic tandem solar cell. This tandem architecture integrates two complementary light-absorbing subcells to harvest a broader range of the solar spectrum than traditional single-layer devices.

The study was published on Monday in the journal Nature.

Unlike traditional silicon solar cells — which are generally rigid and require high-temperature manufacturing — these next-generation cells use a mix of "perovskite" — a synthetic, highly customizable crystal structure, and organic materials. Because they are lightweight, flexible and can be printed at low temperatures like ink on paper, they promise a cheaper and easier route to mass manufacturing.

In a perovskite-organic tandem solar cell, the top perovskite layer is customized to capture high-energy light like ultraviolet rays, while the organic bottom layer absorbs near-infrared light. The two materials work in tandem: the top layer blocks harsh ultraviolet rays that could damage the organic bottom layer, while the water-resistant organic layer protects the moisture-sensitive perovskite above it.

"This design allows scientists to 'tune' the material, essentially adjusting the specific colors of light it absorbs," said Meng Lei, a professor at the Institute of Chemistry of the Chinese Academy of Sciences and a corresponding author of the study.

Despite their promise, hybrid solar cells have long faced a major roadblock: internal chemical separation.

To absorb the right colors of light, the perovskite layer is made by incorporating different halide components, particularly iodide and bromide. However, these components tend to separate. They fail to mix uniformly during precursor-to-film conversion and crystallization, and they separate again under prolonged exposure to sunlight during operation. This chemical separation creates microscopic defects, causing the solar cell to degrade rapidly.

To solve this, Meng's team created a smart, photo-transformable additive molecule called TDB.

TDB acts as a two-stage stabilizer. During manufacturing, it regulates crystallization dynamics and promotes homogeneous halide mixing during film formation. Then, once the solar cell is operating in the sun, the light triggers the TDB molecules at the material's microscopic boundaries to transform, binding tightly to the surface. This suppresses halide migration and prevents defects from forming under sunlight.

"The light-transformable nature of TDB allows it to sequentially address challenges at two different stages," said Wu Ruihan, a doctoral candidate at the institute and the study's first author.

The results yielded a highly stable, high-performance solar cell. The optimized perovskite layer achieved an open-circuit voltage — the maximum voltage generated by the solar cell under illumination — of 1.42 volts, a record for this class of solar cell.

When fully integrated into the tandem device, the technology hit a total power conversion efficiency of 28.80 percent, with a certified steady-state efficiency of 28.04 percent. Crucially, the device retained 90 percent of its initial performance after 625 hours of continuous illumination, demonstrating that high efficiency does not have to come at the cost of durability.

Li Yongfang, an academician of the Chinese Academy of Sciences and a corresponding author of the study, said these ultra-lightweight, flexible cells could accelerate the global transition to clean energy.

Li noted that the technology holds strong potential for ground-level applications, such as solar panels integrated directly into building windows, wearable electronics, drones and portable power packs. It could also prove vital for aerospace applications, including powering satellites, space stations and deep-space missions.