Longi, a Chinese solar manufacturer, describes in a recent scientific paper the 27.81% efficient hybrid interdigitated back-contact (HIBC) silicon solar cell it unveiled in April 2025. The device reportedly features passivated tunneling contacts and dielectric passivation layers, while incorporating both n-type and p-type contacts. The paper, titled “Silicon solar cells with hybrid back contacts,” was published last week in Nature and details that the cell is built on passivated tunneling contacts with dielectric passivation and dual-type contacts.
Key performance metrics reported by Longi and its collaborators include a world-record efficiency of 27.81% on a cell with an active surface of 133.63 cm², a short-circuit current of 5,698 mA, an open-circuit voltage of 744.9 mV, and a fill factor of 87.55%. The ISFH (Institute for Solar Energy Research Hamelin, Germany) certified the result, confirming it as the highest efficiency for silicon solar cells to date. A company spokesperson emphasized that achieving these gains involved redesigning both cell architecture and material systems to balance optical management with carrier transport efficiency.
In the discussion accompanying the paper, researchers note that optimizing the a-Si layer thickness, its optical properties, and laser processing parameters (fluence and pulse duration) was crucial in balancing passivation and conductivity. The reported advances are framed as improvements in both optical management and carrier transport, enabling higher conversion efficiency while maintaining favorable electrical characteristics.
“By redesigning both the cell architecture and material systems, we achieved simultaneous breakthroughs in optical management and carrier transport efficiency.”
“Achieving an optimal balance between passivation and conductivity requires careful tuning of the a-Si layer thickness, its optical properties, and laser parameters such as fluence and pulse duration.”
According to the sources, the April 2025 announcement had previously claimed the device held the world’s highest silicon-solar-cell efficiency, with ISFH verification. The detailed paper in Nature provides the technical context for these claims, including the dual-contact approach and the passivated tunneling contacts strategy that underpins the reported performance.
Author’s note: The reported breakthrough highlights the importance of integrated architectural and material innovations in pushing silicon solar cell efficiencies higher, while maintaining manufacturability and scalable device design.
Author’s summary: A comprehensive study by Longi and collaborators details a 27.81% efficient HIBC silicon solar cell, certified by ISFH, attributed to passivated tunneling contacts, dielectric passivation, and both n-type and p-type contacts, with emphasis on optical and carrier-transport optimization.