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Single-atom interface engineering opens dual high-speed pathways for electrons and holes in next-generation solar cells
A Korean research team has dramatically improved the efficiency and lifetime of perovskite solar cells, regarded as next-generation solar cells, by overturning the conventional design paradigm. The study is expected to mark a turning point that significantly accelerates the commercialization of perovskite solar cells.
Sungkyunkwan University announced on the 3rd that Professor Nam-Gyu Park’s team in the Department of Chemical Engineering, together with Professor Sang-Wook Lee’s team in the same department, has developed a new interface design technology that controls the transport pathways of electrons and holes by replacing just a single atom in the organic molecules inside perovskite solar cells.
Perovskite solar cells are attracting attention as next-generation solar cells because they are cheaper and more efficient than conventional silicon solar cells. Their drawback has been a shorter lifetime compared to silicon counterparts.
The lifetime of perovskite solar cells is shortened when the flow of “electrons” and “holes” inside the device is blocked.
When a solar cell is exposed to sunlight, negatively charged electrons and positively charged holes travel along wires, generating current. For the solar cell to produce electricity smoothly, electrons and holes must move unhindered to each electrode through pathways in opposite directions.
Until now, a “doping” approach—adding chemical substances—has been used to facilitate the flow of electrons and holes. However, over time, the added chemicals can migrate from their original positions or react with other chemicals inside the solar cell. As a result, electrons and holes can no longer flow smoothly.
Instead of adding chemicals, the research team proposed an innovative solution: changing the way the crystals of the constituent materials in perovskite solar cells are connected.
In perovskite solar cells, the key part that absorbs light and generates electrons and holes is called the “photoactive layer.” Inside this photoactive layer, octahedral crystals composed of iodine and lead are connected like a sponge. Previously, chemicals were doped into this photoactive layer.
The team replaced just one atom inside the octahedral crystals that make up the photoactive layer. When nitrogen (N) was introduced, the octahedral crystals formed single-chain structures, allowing electrons to flow without obstruction. When sulfur (S) was introduced, the octahedral crystals connected into double-chain structures, guiding holes to exit efficiently.
By swapping a single atom, they controlled the pathways along which the crystals connect, effectively opening dedicated “high-speed highways” on both sides for electrons and holes to travel.
When the team applied this structure to both interfaces of the solar cell, the device achieved a world-class power conversion efficiency of 27.61% (certified at 27.19%).
Even when scaled up to a large-area module of 665 square centimeters, the cells exhibited a high power conversion efficiency of 22.26%. Under harsh conditions of continuous illumination for 2,000 hours, they retained 97.8% of their initial performance, demonstrating outstanding durability.
Professor Park is regarded as a world-leading scholar in the field of perovskite solar cells. He said, “This study is the first in the world to demonstrate that the flow of electrons and holes can be perfectly controlled solely through changes in the crystal connection structure via single-atom substitution, without any artificial chemical doping,” adding, “We expect it will greatly accelerate the commercialization of high-efficiency, high-stability perovskite solar cells in the future.”
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doi: 10.1038/s41563-026-02722-3
