A Clever Coating Pushes Tandem Solar Cells Toward Higher Efficiency

A team of Chinese scientists has nudged tandem solar technology a little closer to its potential, reporting a perovskite-silicon solar cell with a certified efficiency of 32.89% and a measured peak of 33.33%. The result, described in an article published on May 21, 2026, comes from researchers at the Ningbo Institute of Materials Technology and Engineering of the Chinese Academy of Sciences, working with colleagues at Soochow University, Taizhou University, and an equipment company.

Tandem cells stack a thin perovskite layer on top of conventional silicon, letting the two materials capture different slices of sunlight and convert more of it into electricity than silicon alone. The challenge lies in the texture of the silicon surface, which is covered in microscopic pyramids. The sharp peaks of those pyramids are difficult to coat evenly, and tiny defects there can quietly drain away performance.

“89% and a measured peak of 33.”

The team’s solution, which they call peak-selective passivation, is elegant in its precision. Using polystyrene nanospheres as a template, they deposited an ultra-thin insulating layer of aluminum oxide specifically onto the pyramid peaks, smoothing over the trouble spots without disturbing the rest of the surface. Just as important as the headline efficiency, the cell retained about 90% of its initial performance after 1,000 hours of continuous operation, addressing the durability concerns that have long shadowed perovskite devices. The work was published in the journal Matter.

The authors are clear that the field’s record sits a little higher, around 35%, so this is a strong contribution rather than an outright crown. But the steady, incremental march of solar efficiency is precisely what makes clean power cheaper and more abundant over time. Each fraction of a percent, won through clever chemistry and patient engineering, brings the world a step closer to electricity that is both affordable and kind to the planet.