Additive-Free, Low-Temperature Crystallization of Stable α-FAPbI3 Perovskite

Du T, Macdonald TJ, Yang RX, Li M, Jiang Z, Mohan L, Xu W, Su Z, Gao X, Whiteley R, Lin CT, Min G, Haque SA, Durrant JR, Persson KA, Mclachlan MA, Briscoe J (2022)

Publication Type: Journal article

Publication year: 2022

Journal

Advanced Materials Wiley

DOI: 10.1002/adma.202107850

Abstract

Formamidinium lead triiodide (FAPbI3) is attractive for photovoltaic devices due to its optimal bandgap at around 1.45 eV and improved thermal stability compared with methylammonium-based perovskites. Crystallization of phase-pure α-FAPbI3 conventionally requires high-temperature thermal annealing at 150 °C whilst the obtained α-FAPbI3 is metastable at room temperature. Here, aerosol-assisted crystallization (AAC) is reported, which converts yellow δ-FAPbI3 into black α-FAPbI3 at only 100 °C using precursor solutions containing only lead iodide and formamidinium iodide with no chemical additives. The obtained α-FAPbI3 exhibits remarkably enhanced stability compared to the 150 °C annealed counterparts, in combination with improvements in film crystallinity and photoluminescence yield. Using X-ray diffraction, X-ray scattering, and density functional theory simulation, it is identified that relaxation of residual tensile strains, achieved through the lower annealing temperature and post-crystallization crystal growth during AAC, is the key factor that facilitates the formation of phase-stable α-FAPbI3. This overcomes the strain-induced lattice expansion that is known to cause the metastability of α-FAPbI3. Accordingly, pure FAPbI3 p–i–n solar cells are reported, facilitated by the low-temperature (≤100 °C) AAC processing, which demonstrates increases of both power conversion efficiency and operational stability compared to devices fabricated using 150 °C annealed films.

Involved external institutions

Queen Mary University of London GB United Kingdom (GB) Lawrence Berkeley National Laboratory (LBNL) US United States (USA) (US) Henan University / 河南大学 CN China (CN) Imperial College London / The Imperial College of Science, Technology and Medicine GB United Kingdom (GB) Chinese Academy of Sciences (CAS) / 中国科学院 CN China (CN)

How to cite

APA:

Du, T., Macdonald, T.J., Yang, R.X., Li, M., Jiang, Z., Mohan, L.,... Briscoe, J. (2022). Additive-Free, Low-Temperature Crystallization of Stable α-FAPbI3 Perovskite. Advanced Materials. https://dx.doi.org/10.1002/adma.202107850

MLA:

Du, Tian, et al. "Additive-Free, Low-Temperature Crystallization of Stable α-FAPbI3 Perovskite." Advanced Materials (2022).

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