In-situ polymerized zwitterionic elastomers for efficient and stable perovskite solar cells

Abstract

Ensuring durable operation while maintaining high efficiency remains a major challenge for perovskite solar cells, mainly due to defect-mediated recombination, mobile ions, and accumulated lattice stress. Here, we simultaneously achieve significant improvements in both the efficiency and stability of perovskite solar cells though introducing a zwitterionic compound as a multifunctional additive that concurrently modulates crystallization, passivates defects, limits ion migration, and relaxes residual stress within the perovskite layer. The multifunctionality of the additive enabled by its distinct molecular-state evolution. It initially acts as a small molecule with effective coordination capability, guiding the formation of high-quality perovskite and passivating trap states. During film formation, it undergoes in situ polymerization, forming a zwitterionic elastomer network at grain boundaries that constrains ionic movement and releases residual stress. This integrated approach leads to perovskite films with improved crystallization quality and reduced non-radiative loss pathways. Devices produced using this strategy exhibit a power conversion efficiency (PCE) of 27.09% (26.69% certified) as well as excellent operational and thermal cycling stability, highlighting the effectiveness of this synergistic strategy in advancing perovskite photovoltaic performance and stability.