Scientists in Japan have set a new record for copper gallium selenide (CuGaSe₂) solar cells. They achieved a power conversion efficiency of 12.28%. This breakthrough comes from the National Institute of Advanced Industrial Science & Technology (AIST).
CuGaSe₂ is a semiconductor material. It is similar to the more common copper indium gallium selenide (CIGS). It can absorb visible sunlight very well, making it good for solar energy. This material is also promising for future solar cells that do not use indium.
New Record for Wide-Bandgap Solar Cells
The CuGaSe₂ material used in the new solar cell can handle defects well. This means it performs strongly even if its crystal structure is not perfect, according to pv magazine.
We're a new kind of news feed.
Regular news is designed to drain you. We're a non-profit built to restore you. Every story we publish is scored for impact, progress, and hope.
Start Your News DetoxShogo Ishizuka, the lead author of the study, said the 12.28% efficiency is the highest ever for wide-bandgap chalcogenide solar cells in the 1.65–1.75 eV range. This includes indium-free chalcopyrite or CIGS-related solar cells. It beats previous records for CuGaSe₂-aluminum solar cells.
AIST's Photovoltaic Calibration, Standards and Measurement Team checked the solar cell's performance. The new design builds on a previous one from AIST in 2024. It adds aluminum to the back of the CuGaSe₂ films. This change improves the cell's voltage, fill factor, and overall efficiency. It does this by creating a back-surface field (BSF) that helps collect minority carriers and reduces energy loss.
Aluminum and Rubidium Boost Performance
The record-setting solar cell uses a copper gallium selenide absorber. This absorber is grown using a three-stage process. Aluminum and rubidium fluoride are added during the first stage. More rubidium fluoride is added in the final stage. This helps increase the open-circuit voltage while keeping high efficiency.
The cell is built on a soda-lime glass base with a molybdenum back contact. On top of this is the indium-free chalcopyrite absorber. Then comes a cadmium sulfide buffer layer, a zinc oxide window layer, and a metal grid electrode. This layered structure helps collect carriers and maximize the solar cell's performance, pv magazine noted.
The scientists said their work is focused on basic research for wide-bandgap devices. These devices are meant for the top cells in tandem solar cells. Ishizuka explained that a full prototype would need a compatible bottom cell and tandem technology. So, the research is not yet ready for mass production. He added that they have not done a detailed cost assessment because the project is still in early research stages.
