Xu Xipeng's team at Huaqiao University published a research paper titled "Surface reconstruction of wide-bandgap perovskites enables efficient perovskite/silicon tandem solar cells" in the journal Nature Communications. Fang Zheng is the first author, and Xu Xipeng, Wei Zhanhua, and Xie Liqiang are co-corresponding authors.
Key Highlights: This paper developed a surface reconstruction method that removes the defect-rich crystal surface through nanopolishing and then passivates the newly exposed highly crystalline surface. Using a 1.67 eV perovskite absorber layer, they achieved certified efficiencies of 23.67% and 21.70% for opaque and semi-transparent perovskite solar cells, respectively. Furthermore, they demonstrated a four-terminal perovskite/silicon tandem solar cell with a certified efficiency of 33.10% at an aperture area of 1 cm².
Wide-bandgap perovskite solar cells are crucial for the development of perovskite/silicon tandem solar cells. Wide-bandgap perovskites are typically prepared using mixed Br-I halide compositions. The resulting crystal films suffer from problems such as disordered crystal stacking, random distribution of vacancies, and halide compositions, leading to high surface defects. Defect-rich crystal surfaces can lead to severe interfacial carrier loss and phase separation, thus degrading device performance.
In light of this, the team of Xu Xipeng, Wei Zhanhua, and Xie Liqiang from Huaqiao University developed a surface reconstruction method that removes the defect-rich crystal surface through nanopolishing and then passivates the newly exposed high-crystallinity surface. This method refreshes the perovskite/electron transport interface and releases residual lattice strain, improving charge collection efficiency and suppressing ion migration in wide-bandgap perovskites. As a result, they achieved certified efficiencies of 23.67% and 21.70% for opaque and semi-transparent perovskite solar cells using a 1.67 eV perovskite absorber. Furthermore, they achieved a certified efficiency of 33.10% for a four-terminal perovskite/silicon tandem solar cell with an aperture area of 1 cm².
This study demonstrates that the surface reconstruction method can effectively remove defect regions on the perovskite film surface caused by insufficient crystallization, suppress ion migration, and release residual stress in the perovskite film. It is revealed that surface passivation of perovskite films with high defect density (such as wide-bandgap perovskite films) requires pre-reduction of the defect density in the initial film, which points the way for the design of surface engineering strategies to further improve the performance of wide-bandgap perovskite solar cells.
Source：
https://doi.org/10.1038/s41467-024-54925-4