Toughened self-assembled monolayers for durable perovskite solar cells

17 Sep 2025

Published on nature (17 September 2025)

Author(s): Wenlin Jiang, Geping Qu, Xiaofeng Huang, Xia Chen, Linyuan Chi, Tonghui Wang, Chun-To Wong, Francis R. Lin, Chunlei Yang, Qing Jiang, Shengfan Wu, Jie Zhang & Alex K.-Y. Jen

Abstract

Hole-selective self-assembled monolayers (SAMs)1,2 have played a key role in driving the certified power conversion efficiency (PCE) of inverted perovskite solar cells3–5 to 26.7% (ref. 6). However, their instability often compromises the operational performance of devices, strongly hindering their practical applications7,8. Here we employ a crosslinkable co-SAM to enhance the conformational stability of hole-selective SAMs against external stresses, while suppressing the formation of defects and voids in SAM during self-assembly. The azide-containing SAM can be thermally activated to form a crosslinked and densely assembled co-SAM with a thermally stable conformation and preferred orientation. This effectively minimizes substrate surface exposure caused by wiggling of loose SAMs under thermal stress, preventing perovskite decomposition. This enables a certified PCE of 26.92% to be achieved for the best-performing cell, which also possesses excellent thermal stability with negligible decay under maximumpower-point tracking at 85 °C for 1,000 h. It also retains >98% of initial PCE after 700 repetitive thermal cycles between −40 °C and 85 °C, representing the state of the art of the field. This work offers an in-depth understanding of SAM degradation mechanisms to guide the design of a more robust buried interface for SAM-based devices adopting high-roughness substrates to realize highly efficient and durable perovskite solar cells.