Binary antisolvent bathing enabled highly efficient and uniform large-area perovskite solar cells

There is a high commercial demand for the scaled-up perovskite solar cells (PSCs) with excellent power-conversion efficiency. However, only a limited number of fabrication methods for the formation of large-area perovskite films with uniform morphology and high crystallinity have been reported. Herein, we propose a facile binary antisolvent bathing approach for triple-cation-based perovskite, which is highly compatible with large-area fabrication. The wet perovskite precursor films were submerged in a binary antisolvent bath comprising ethyl acetate and diethyl ether, resulting in crystallization retardation. The decelerated nucleation and growth induced enlarged perovskite crystals with highly preferential orientation alignment along the [1 0 0] direction, perpendicular to the substrate. The increased grain size and highly preferred crystal orientation not only benefit effective charge extraction but also suppress non-radiative recombination by reducing the defect density of the perovskite films. The photovoltaic performance was greatly improved from 17.30% (single antisolvent bath) to 19.38% (binary antisolvent bath). Furthermore, the binary antisolvent approach successfully tuned the vapor pressure of the binary antisolvent, facilitating rapid elimination of the residual antisolvent in the wet precursor film after bathing and enabling the fabrication of uniform large-area PSCs with high performance.