Spontaneous low-temperature crystallization of α-FAPbI3 for highly efficient perovskite solar cells

Taiyang Zhang; Qiaoling Xu; Feng Xu; Yuhao Fu; Yong Wang; Yanfa Yan; Lijun Zhang; Yixin Zhao

doi:10.1016/j.scib.2019.08.029

Spontaneous low-temperature crystallization of α-FAPbI₃ for highly efficient perovskite solar cells

Sci Bull (Beijing). 2019 Nov 15;64(21):1608-1616. doi: 10.1016/j.scib.2019.08.029. Epub 2019 Aug 28.

Authors

Taiyang Zhang¹, Qiaoling Xu², Feng Xu¹, Yuhao Fu², Yong Wang¹, Yanfa Yan³, Lijun Zhang⁴, Yixin Zhao⁵

Affiliations

¹ School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
² Key Laboratory of Automobile Materials, Ministry of Education, School of Materials Science and Engineering, Jilin University, Changchun 130012, China.
³ Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA.
⁴ Key Laboratory of Automobile Materials, Ministry of Education, School of Materials Science and Engineering, Jilin University, Changchun 130012, China; State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China. Electronic address: lijun_zhang@jlu.edu.cn.
⁵ School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China. Electronic address: yixin.zhao@sjtu.edu.cn.

PMID: 36659573
DOI: 10.1016/j.scib.2019.08.029

Abstract

Formamidinium lead triiodide (HC(NH₂)₂PbI₃ or FAPbI₃) is a promising light absorber for high-efficiency perovskite solar cells because of its superior light absorption range and thermal stability to CH₃NH₃PbI₃ (MAPbI₃). Unfortunately, it is difficult to fabricate high-quality FAPbI₃ thin films to surpass the MAPbI₃-based cells due to easily forming unwanted but more stable yellow δ-phase and thus requiring high annealing-temperature for wanted photovoltaic-active black α-phase. Herein, we reported a novel low-temperature fabrication of highly crystallized α-FAPbI₃ film exhibiting uniaxial-oriented nature with large grain sizes up to 2 μm. First-principles energetic calculations predicted that this novel deposition should be ascribed to the formation of a high-energy metastable two-dimensional (2D) intermediate of MAFAPbI₃Cl followed by a spontaneous conversion to α-FAPbI₃. The ions exchange reaction during this MAFAPbI₃Cl-FAPbI₃ conversion account for the perovskite film uniaxial-oriented grown along the (1 1 1) direction. This large-grain and uniaxial-oriented grown α-FAPbI₃ based solar cells exhibited an efficiency up to 20.4% accompanying with low density-voltage (J-V) hysteresis and high stability.

Keywords: FAPbI(3); Perovskite solar cells; Spontaneous crystallization; Two-dimensional (2D) perovskites.