Ink engineering using 1,3-dimethyl-2-imidazolidinone solvent for efficient inkjet-printed triple-cationic perovskite solar cells

Ink engineering increases the quality and uniformity of large-scale perovskite films for efficient inkjet-printed perovskite solar cells (IJP-PSCs). The absorber layer in PSCs must be pinhole- and crack-free, highly uniform, with minimum defects, and have better optoelectronic properties, to improve PSC device performance. Herein, a different strategy, such as solvents with high boiling points (BPs), is used to modify the perovskite inks to obtain uniform and better-quality IJP-perovskite films. The perovskite film prepared with a 1,3-dimethyl-2-imidazolidinone (DMI) solvent is highly uniform (>96 %), thicker, with a smoother surface, and contains bigger grains than γ-butyrolactone (GBL) based IJP-perovskites. The DMI solvent-based IJP-PSC device shows a greater than 17.5 % power conversion efficiency (PCE), which is much higher than that possible with GBL-based devices (PCE ∼13.8 %). The better performance of the IJP-PSC device is mainly due to the film's uniformity, large grains, and well-formed structures, which reduce the occurrence of specific chemical reactions within the perovskite material. The presented ink engineering strategy to develop highly uniform IJP perovskite films has the potential to be applied to perovskite solar modules.