Nonalloyed α-phase formamidinium lead triiodide solar cells through iodine intercalation

Yu Zhang; Yanrun Chen; Guilin Liu; Yuetong Wu; Zhenyu Guo; Rundong Fan; Kailin Li; Huifen Liu; Yepin Zhao; Tim Kodalle; Yihua Chen; Cheng Zhu; Yang Bai; Qi Chen; Huanping Zhou

doi:10.1126/science.ads8968

Nonalloyed α-phase formamidinium lead triiodide solar cells through iodine intercalation

Science. 2025 Jan 17;387(6731):284-290. doi: 10.1126/science.ads8968. Epub 2025 Jan 16.

Authors

Yu Zhang^#¹, Yanrun Chen^#¹, Guilin Liu², Yuetong Wu¹, Zhenyu Guo¹, Rundong Fan¹, Kailin Li¹, Huifen Liu¹, Yepin Zhao³, Tim Kodalle^{4

5

6}, Yihua Chen⁷, Cheng Zhu⁷, Yang Bai⁷, Qi Chen⁷, Huanping Zhou^{1

8

9}

Affiliations

¹ Beijing Key Laboratory for Theory and Technology of Advanced Battery Materials, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, School of Materials Science and Engineering, Peking University, Beijing, P. R. China.
² School of Science, Jiangnan University, Wuxi, Jiangsu, P. R. China.
³ Department of Materials Science and Engineering, University of California Los Angeles, Los Angeles, CA, USA.
⁴ Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
⁵ Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
⁶ Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
⁷ School of Materials Science and Engineering, Beijing Institute of Technology, Beijing, P. R. China.
⁸ Institute of Carbon Neutrality, Peking University, Beijing, P. R. China.
⁹ Southwest United Graduate School, Kunming, P. R. China.

^# Contributed equally.

PMID: 39818906
DOI: 10.1126/science.ads8968

Abstract

Formamidinium lead triiodide (FAPbI₃) is considered the most promising composition for high-performing single-junction solar cells. However, nonalloyed α-FAPbI₃ is metastable with respect to the photoinactive δ-phase. We have developed a kinetic modulation strategy to fabricate high-quality and stable nonalloyed α-FAPbI₃ films, assisted by cogenetic volatile iodine intercalation and decalation. The intercalation of iodine facilitated the formation of corner-sharing Pb-I framework building blocks and reduced the kinetic barrier for α-FAPbI₃ formation, whereas the iodine decalation improved the final perovskite film quality in terms of composition purity and overall homogeneity. Solar cells based on this nonalloyed α-FAPbI₃ (free of other extrinsic composition ions) achieved a power conversion efficiency of >24%. The devices also exhibited excellent durability, retaining 99% of their original power conversion efficiency after operating for more than 1100 hours at 85° ± 5°C under illumination.