Abstract:

One-step method assisted by antisolvent is the most useful strategy to fabricate perovskite solar cells (PSCs) with high power conversion efficiency (PCE). Nevertheless, the narrow processing window and strict solvent ratio restricts the fabrication of large-area and uniform perovskite films. Herein, by thoroughly investigating the interaction between solvents and antisolvents during the processing, we discover the significant role of the typical solvent of dimethylformamide in the process of antisolvent washing and we demonstrate a solvent-antisolvent interaction model to understand the originality of narrow processing window and solvent ratio based on chlorobenzene. Furthermore, we introduce a green antisolvent ── Ethyl Methyl Carbonate, with a large processing window from 2s to 35s, and a prolonged dimethylformamide: dimethyl sulfoxide volume ratio varying from 7:3 to 0:10 in the precursor solution. The obtained PSCs show remarkable efficiency of 22.08% on rigid substrates, and 19.14% on flexible substrates. In a parallel effort, we demonstrate a uniform and large-area (6×6 cm2) flexible perovskite film, exhibiting the highest PCE of 18.60%.