Efficient triple-mesoscopic perovskite solar mini-modules fabricated with slot-die coating

Triple-mesoscopic perovskite solar cells (PSCs) based on the architecture of TiO2/ZrO2/Carbon have attracted much attention due to the high stability and simple fabrication process. The screen-printing technique enables easy scaling-up of the cell area to mini-modules (10–200 cm2), submodules (200–800 cm2) and modules (≥800 cm2). However, it is challenging to achieve uniform deposition of the perovskites in large-area mesoporous scaffolds. Herein we employed slot-die coating to deposit the perovskite precursor on the scaffold. By investigating the infiltration mechanism of the precursor in the mesoporous scaffold according to Lucas-Washburn model, the coating parameters were optimized. Correspondingly, a power conversion efficiency of 12.87% was obtained at an active area of 60.08 cm2, which is the highest value reported for such triple-mesoscopic device architecture. The short-circuit current density of the sub-cell reached 22.49 mA cm−2, which equaled 95.7% of that for small-area (0.1 cm2, 23.50 mA cm−2) lab cells, and the open-circuit voltage of the sub-cell reached 0.94 V, which is slightly higher than that of lab cells (0.1 cm2, 0.93 V). The results indicated that slot-die coating can be effectively applied for the infiltration of the perovskites in mesoporous films and devices towards mass-production.