Hafnium oxide interface stabilization for efficient, photothermally stable perovskite solar cells
Yuanhang Yang, Siyang Cheng, Xiaotian Yang, Mubai Li, Xueliang Zhu, Zhongji Yang, Yue Zheng, Yong Liu, Qianqian Lin, Ning Yan, Shengjun Yuan, Zhiping Wang
Abstract
Organic molecular layers at both hole- and electron-selective interfaces are essential for achieving high-efficiency perovskite solar cells, yet their limited photothermal stability hinders long-term device operation. We used atomic layer deposition to deposit hafnium oxide (HfO x ) interlayers to stabilize these molecular interfaces under operational stress. At the NiO x /self-assembled monolayer (SAM) interface, a hydroxyl-rich, Lewis-acidic n-HfO x layer (n denotes negative fixed-charge polarity) promoted tridentate phosphonic acid coordination and enhanced SAM retention and thermal durability. At the perovskite/C 60 interface, the p-HfO x layer (p denotes positive fixed-charge polarity) anchored 3-fluorophenylethylammonium iodide (3F-PEAI) through Hf⋯F interactions that also acted as a diffusion barrier against halide- and silver-ion migration. Devices achieved a power conversion efficiency of 27.1% (26.6% certified) and retained more than 90% of their initial efficiency for ~5000 hours under 1-sun equivalent illumination at 85°C in ambient air.