Reduction-Active Antisolvent: A Universal and Innovative Strategy of Further Ameliorating Additive Optimization for High Efficiency Perovskite Solar Cells.

To further ameliorate current additive engineering of perovskites for viable applications, the inherent limitations should be overcome; these include weakened coordination of the dopants to the [PbI ₆ ] ^4- octahedra during crystallization and ubiquity of ineffective bonding sites. Herein, we introduce a facile strategy for synthesizing a reduction-active antisolvent. Washing with reduction-active PEDOT:PSS-blended antisolvent substantially enhances the intrinsic polarity of the Lewis acid (Pb ²⁺ ) in [PbI ₆ ] ^4- octahedra, which causes significant strengthening of the coordinate bonding between additives and perovskite. Thus, coordination of the additive to the perovskite becomes much stable. Additionally, the enhanced coordination ability of Pb ²⁺ can enhance the effective bonding sites and further enhance the efficacy of additive optimization to the perovskite. Here, we demonstrate five different additives as dopant bases and repeatedly verify the universality of this approach. The photovoltaic performance and stability of doped-MAPbI ₃ devices are further improved, revealing the advanced potential of additive engineering.