Toward sustainable manufacturing of highly efficient and stable semi-transparent perovskite solar cells: The critical role of green solvent properties

Perovskite solar cells, promising a bright future in the energy market, are now being prioritized for high-throughput production to match their remarkable success at the laboratory scale. However, the use of toxic solvents proved to be one of the major constraints on scaling up production. Herein, a green solvent system consist of dimethyl sulfoxide (DMSO) and 1-dodecyl-3-methylimidazolium chloride ([C₁₂MIM]Cl) ionic liquids (ILs) was developed to modulate the crystallization of wide-bandgap (WBG) perovskite films combined with a antisolvent-free process, i.e., nitrogen (N₂) quenching method. The [C₁₂MIM]Cl IL promoted the crystallization of WBG perovskite films with large grain sizes, reduced photo-active PbI₂, modulated residual strain, prolonged carrier lifetimes as well as improved energy alignment. Consequently, the [C₁₂MIM]Cl-modified single-junction 1.77 eV perovskite solar cells (PSCs) achieved a champion efficiency of 18.75 % with an excellent operational stability, retaining an initial PCE of 93 % after 2000 h of maximum-power-point tacking test. Meanwhile, the positive effect of the [C₁₂MIM]Cl ILs was universal in perovskite with different bandgaps at 1.53, 1.68 and 1.72 eV, respectively. Furthermore, stacking semi-transparent [C₁₂MIM]Cl-modified 1.77 eV WBG PSCs as top cells coupled with 1.27 eV OPV or 1.24 eV Sn-Pb PSC as bottom cells for the 4 T tandem configuration showed impressive PCE of 26.01 % and 27.44 %, respectively. This study opens a new avenue toward the sustainable fabrication of highly efficient and stable perovskite-based semitransparent and tandem solar cells.