Key takeaways:
A research team from NIMTE along with partners has developed a peak-selective passivation strategy for textured perovskite-silicon tandem cells
Localized Al₂O₃ layers at silicon pyramid peaks helped suppress shunting pathways and non-radiative recombination losses
The tandem cells achieved 33.33% efficiency and retained 90% of their initial performance after 1,000 hours of MPP tracking
Perovskite-silicon tandem technology is fast-moving towards industrially compatible device architectures. Work is underway to iron out the problems, with a focus not only on efficiency but also on the losses associated with bottom-cell architectures and interface engineering.
One of the challenges in these tandem structures is achieving a uniform perovskite layer on the industrial pyramid-textured silicon surfaces. The presence of pyramids leads to a non-uniform layer of perovskite, especially at the pyramid peaks. This creates localized weak spots that are prone to shunting, optical losses, and long-term instability of the top cell due to insufficient perovskite thickness at the peaks.
Some approaches, such as submicron-scale texturing, submicron pyramids, and sinusoidal periodic nanotextures, have offered solutions, but maintaining bath concentration across batches in large-scale production is a challenge.
To address this issue, researchers from the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences (CAS), together with Soochow University, Taizhou University, and S.C Exact Equipment Co., have developed a peak-selective passivation strategy for perovskite-silicon tandem solar cells.
The method, termed peak-selective passivation (PSP), begins with the self-assembly of polystyrene nanospheres on the textured silicon surface to serve as a template. With this step, only the pyramid peaks are exposed, enabling selective deposition of aluminum oxide (Al2O3) on them via electron-beam thermal evaporation. After deposition, the polystyrene nanospheres are removed using a lift-off process.
Using this approach, the team achieved a tandem cell with a maximum efficiency of 33.33% and a certified efficiency of 32.98% on a 1 cm² device. These cells retained 90% of their initial performance after 1,000 h of maximum power point tracking.
This study highlights a broader trend in tandem cell development, where interface engineering and localized passivation are becoming increasingly important for adapting perovskite processing to industrial silicon textures and scalable manufacturing routes.