A route towards the fabrication of large-scale and high-quality perovskite films for optoelectronic devices

Abstract

Halide perovskite materials have been extensively explored for their unique electrical, optical, magnetic, and catalytic properties. Most notably, solar cells based on perovskite thin films have improved their power conversion efficiency from 3.8% to over 25% during the last 12 years. However, it is still a challenge to develop a perovskite-based ink, suitable for upscaling the fabrication process of high-quality perovskite films with extreme purity, good crystallinity, and complete coverage over the deposition area. This is particularly important if the perovskite films are to be used for the scaled production of optoelectronic devices. Therefore, to make halide perovskites commercially available for various applications, it is vital to develop a reliable and highly robust deposition method, which can then be transferred to industry. Herein, the development of perovskite precursor inks suitable for use at low-temperature and vacuum-free solution-based deposition processes is reported. These inks can be further tailored according to the requirements of the deposition method, i.e., we propose their use with the industrially viable deposition technique called "slot-die coating". Furthermore, a route for the preparation of low-cost and high-volume manufacturing of perovskite films on both rigid and flexible substrates is suggested in this paper. The presented approach is suitable for the fabrication of any functional layers of perovskites, that can be employed in various scaled applications, and it seeks the potential and the methodology for perovskite film deposition that is scalable to industrial standards.

Figure 1

Schematic representation of different coating conditions used in this study: (a) coating at elevated temperature without N₂ gas blowing; (b) coating at elevated temperature with N₂ gas blowing; and (c) coating at room temperature with N₂ gas blowing.

Figure 2

SEM images of MAPbI₃ thin films deposited on ITO substrates using the following methods: (a) ACN-based ink deposited on a hot substrate (sample 1); (b) ACN-based ink deposited on a hot substrate with N₂ blowing (sample 2); (c) ACN-based ink deposited on a hot substrate with N₂ blowing and MA-induced post-treatment (sample 3); (d) ACN-based ink deposited at room temperature with N₂ blowing (sample 4); (e) ACN/NMP-based ink deposited at room temperature with an anti-solvent treatment (sample 5); (f) DMF/NMP-based ink deposited at room temperature with an anti-solvent treatment (sample 6).

Figure 3

AFM images of MAPbI₃ thin films deposited on ITO substrates using the following methods: (a) ACN-based ink deposited on a hot substrate (sample 1); (b) ACN-based ink deposited on a hot substrate with N₂ blowing (sample 2); (c) ACN-based ink deposited on a hot substrate with N₂ blowing and MA-induced post-treatment (sample 3); (d) ACN-based ink deposited at room temperature with N₂ blowing (sample 4); (e) ACN/NMP-based ink deposited at room temperature with an anti-solvent treatment (sample 5); (f) DMF/NMP-based ink deposited at room temperature with an anti-solvent treatment (sample 6).

Figure 4

Schematic illustration showing: (a) MA-induced healing post-treatment performed on dry MAPbI₃ perovskite thin film and (b) anti-solvent dipping post-treatment on wet MAPbI₃ perovskite film.

Figure 5

Spectra of: (a) PL; and (b) TRPL of the prepared perovskite thin films for samples 1–6.

Figure 6

Inverted PSCs based on the slot-die perovskite film: (a) schematic device configuration; (b) J–V curves in the dark; and (c) J–V curves at one-sun illumination. Note: the J–V curves represent the behaviour of a champion device.