Moisture-responsive crystallization strategy for efficient CsPbI<sub>3</sub> solar cells fabricated under high-humidity conditions.

Dai, Weideren; Li, Jinhua; Gou, Yanzhuo; Zhang, Jiaqi; Pan, Zexun; Li, Xianglong; Hu, Haojun; Wang, Shulin et al. · Nat Commun · 2026

basic_science · Level V

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Abstract

The intrinsic phase instability of CsPbI<sub>3</sub> perovskites necessitates stringent fabrication conditions, significantly hindering the practical deployment. In the DMA-mediated CsPbI<sub>3</sub> nucleation system, the Cs<sup>+</sup>/DMA<sup>+</sup> ion exchange critically governs the resulting film quality. Here, we employ a moisture-responsive crystallization strategy utilizing propyltriethoxysilane (PTES) to deposite CsPbI<sub>3</sub> under ambient air with high humidity (55%). We demonstrate that the siloxane groups can capture DMA<sup>+</sup> in the intermediate DMAPbI<sub>3</sub>, facilitating DMA<sup>+</sup> extraction and Cs<sup>+</sup> incorporation, thereby accelerating crystallization kinetics. This approach enables CsPbI<sub>3</sub> PSCs to achieve a power conversion efficiency (PCE) of 21.00% with an impressive fill factor (FF) of 86.1% while processing perovskite under relative humidity (RH) of 55%. Higher PCEs of 21.85% and 22.60% (certified 22.02%) were achieved for devices fabricated at a lower RH of 25% and for films spin-coated under an N<sub>2</sub> atmosphere followed by annealing in ambient air, respectively. Furthermore, PTES-treated devices exhibit excellent operational stability under ambient conditions.