Fraunhofer ISE has achieved 31.6% efficiency for a perovskite silicon tandem solar cell
It deposited the perovskite layer on top of the cell that was produced from an industrially textured silicon HJT cell
The researchers expect further increases in efficiency with improvements on the bottom silicon cell
Germany’s Fraunhofer Institute for Solar Energy Systems ISE has produced a new 1 cm² perovskite silicon tandem solar cell with 31.6% efficiency, calling it the highest efficiency to date for a perovskite silicon solar cell made from an industrially-textured silicon heterojunction (HJT) solar cell, and using the hybrid deposition route for the perovskite layer.
It explains that during the manufacturing process, the perovskite layer on the top cell was deposited on an industrially-textured silicon HJT cell, using a hybrid manufacturing route. Both of these are important prerequisites for the industrial production of such cells, according to the institute.
For the bottom subcell, the researchers used a standard silicon solar cell of the type currently in use in the industry today.
The 31.6% efficiency has been certified by the accredited calibration laboratory CalLab of Fraunhofer ISE.
Group Leader Perovskite Materials and Interfaces at Fraunhofer ISE, Dr. Juliane Borchert, said that the pyramid-shaped surface of the silicon solar cell presents a challenge for the top cell of the tandem cell.
“To achieve this value, we concentrated on the perovskite top cell and in particular optimized the passivation between the perovskite layer and the electron transport layer,” adds Borchert. “We expect that further increases in efficiency will be possible by making improvements on the silicon bottom cell.”
She added, “In fact, a special method is needed to apply the perovskite layer evenly on the textured silicon surface. In our labs, we are working on a combined hybrid process of vapor deposition and wet chemical deposition to overcome this obstacle.”
The researchers also put together the learnings from 2 research projects for the latest efficiency claim. One of these, Perovskite-Silicon tandem solar cells: Development of scalable process technologies or PrEsto, identified the suitable production processes for achievable efficiency.
The other project is the MaNiTU or Materials for sustainable tandem solar cells with the highest conversion efficiency. It had 6 Fraunhofer institutes working on developing sustainable, highly efficient, and cost-effective tandem solar cells based on new absorber materials.
Intensive exchange with the scientists from King Abdullah University of Science and Technology (KAUST) was helpful too, according to the German institute. In August 2024, KAUST reported achieving 33.7% conversion efficiency for a perovskite silicon tandem cell using a-cation THTZ-H+ during the manufacturing process (see 33.7% Power Conversion Efficiency For Perovskite Silicon Tandem Cells).