Antisolvent Engineering to Optimize Grain Crystallinity and Hole-Blocking Capability of Perovskite Films for High-Performance Photovoltaics.

With potential commercial applications, inverted perovskite solar cells (PSCs) have received wide-spread attentions as they are compatible with tandem devices and processed at low-temperature. Nevertheless, their efficiencies remain unsatisfactory due to insufficient film quality on hydrophobic hole transport layer and limited hole-blocking capability of the electron transport layer. Herein, 1,3,5-Tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi), an n-type semiconductor, is incorporated into the antisolvent to simultaneously regulate the grain growth and charge transport of perovskite films. TPBi facilitates the crystallization of perovskites along (100) orientation. Besides, TPBi is mainly distributed near the top surface of perovskite film and enhances the hole-blocking capability of the area adjacent to the surface. The superior properties of this film lead to a remarkable improvement in the open-circuit voltage of inverted PSCs. The champion device achieves a high power conversion efficiency of 21.79% while keeping ≈92% of its initial value after 1000 h storage in the ambient atmosphere. This work provides an effective way to evidently promote the performance of inverted PSCs and illustrates its underlaying mechanism.