Overview of Cross-Linkable Perovskite Materials and Recent Advances in High-Performance Solar Cells

Due to the fragile and ionic nature of halide perovskite materials, organic-inorganic hybrid perovskites face significant stability challenges, which remain the primary obstacle to the commercialization of perovskite solar cells (PSCs). Intrinsic defects at the perovskite surface and grain boundaries not only impair device performance but also accelerate the degradation of perovskite materials. In this presentation, we will discuss the innovative approach of incorporating cross-linking polymers into perovskite materials and their impact on PSC performance. In particular, recently, in collaboration with Prof. Gang Li's group, we adopted a novel strategy by pre-embedding a cross-linking initiator, divinyl sulfone (DVS), into the perovskite precursor solution. As a co-solvent, the unique property of DVS implemented the intermediate-dominated perovskite crystallization manipulation through a favored FAI-DVS based solvate transition. More importantly, the controllable asynchronous cross-linking co-polymerization in three dimensions was triggered through the post-treatment of nucleophilic reagent, glycerinum (gly). The copolymer scaffold not only released the residual tensile strain, but also passivated the intrinsic defects at the near-surface region, and provided superior water resistance. As a result, we achieved a maximum PCE over 25% (certified 24.6%) with a maximum VOC of 1.229 V, which is the highest Voc reported in FA-dominated perovskite systems (bandgap ~1.53, with only 0.301 V Voc deficit). This all-around co-polymerization strategy significantly enhanced the moisture resistance of perovskite films and devices, thus achieving the long-term operational stability of PSCs under ambient condition (T90 > 1800 h).