Recrystallizing Sputtered NiO x for Improved Hole Extraction in Perovskite/Silicon Tandem Solar Cells

• Published in: Advanced energy materials 2024-10
• Main Authors: Jin, Yongbin, Feng, Huiping, Li, Yingji, Zhang, Hong, Chen, Xuelin, Zhong, Yawen, Zeng, Qinghua, Huang, Jiarong, Weng, Yalian, Yang, Jinxin, Tian, Chengbo, Zhang, Jinyan, Xie, Liqiang, Wei, Zhanhua
• Format: Article
• Language: English
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.202403911

Sputtering nickel oxide (NiO x ) is a production‐line‐compatible route for depositing hole transport layers (HTL) in perovskite/silicon tandem solar cells. However, this technique often results in films with low crystallinity and structural flaws, which can impair electronic conductivity. Additionally, the complex surface chemistry and inadequate Ni 3+ /Ni 2+ ratio impede the effective binding of self‐assembled monolayers (SAMs), affecting hole extraction at the perovskite/HTL interface. Herein, these issues are addressed using a recrystallization strategy by treating sputtered NiO x thin films with sodium periodate (NaIO 4 ), an industrially available oxidant. This treatment improved crystallinity and increased the Ni 3+ /Ni 2+ ratio, resulting in a higher content of nickel oxyhydroxide. These enhancements strengthened the SAM's anchoring capability on NiO x and improved the hole extraction at the perovskite/HTL interface. Moreover, the NaIO 4 treatment facilitated Na + diffusion within the perovskite layer and minimized phase separation, thus improving device stability. As a result, single‐junction perovskite solar cells with a 1.68 eV bandgap achieve a power conversion efficiency (PCE) of 23.22% for an area of 0.12 cm 2 . Perovskite/silicon tandem cells with an area of 1 cm 2 reached a PCE of 30.48%. Encapsulated tandem devices retained 95% of their initial PCE after 300 h of maximum power point tracking under 1‐sun illumination at 25 °C.