Promoting Exciton Dissociation and Hot Hole Extraction via Hole Transport Layer Engineering Enable Highly Efficient Perovskite Solar Cells With 25.51% Efficiency

Effective exciton dissociation and hot hole extraction in the perovskite layer is of significance for achieving high-performance perovskite solar cells (PSCs), however, the impact of the hole transport layer (HTL) on the two issues is often ignored. Herein, for the first time, an organic semiconductor (WL) is introduced into the well-known Spiro-OMeTAD to afford two different HTLs (Spiro-OMeTAD, Spiro-OMeTAD+WL), which allows this to experimentally explore the dynamics process. We found that WL incorporation can significantly enhance hole transport ability and the built-in electric field of Spiro-OMeTAD+WL-based HTL, which helps to promote the exciton dissociation of the perovskite layer. At the same time, transient absorption spectroscopy studies unambiguously demonstrate that the Spiro-OMeTAD+WL-based HTL exhibits almost two times higher extraction efficiency of hot holes than that of the control Spiro-OMeTAD. Thus, the enhanced exciton dissociation and hot hole extraction can result in the reduced charge accumulation at the perovskite/HTL interface and suppressed charge-carrier recombination in the device. Consequently, the WL-based device shows significantly enhanced power conversion efficiency from 22.35% to 25.51%. The findings of this work can provide some valuable insights for improving PSCs efficiency in the near future.