Self-Healing Ionogel Dual-Network Enables Synergistic Defect Passivation and Strain Relief for High-Efficiency Robust Perovskite Photovoltaics.

The simultaneous realization of high efficiency and long-term stability remains the central challenge for the commercialization of perovskite photovoltaics. The solution processing of perovskite films, while offering significant advantages, inevitably introduces deep-level defects and residual strain, fundamentally limiting both the achievable open-circuit voltage and the device's operational durability. Here, we introduce a molecular design concept that concurrently addresses these pervasive issues by engineering a cross-linked multifunctional ionogel, [HA-AA][EMIES], which is incorporated into the precursor solution. This approach leverages the ionogel's extensive dynamic bond networks and its intrinsic matrix toughening mechanism, achieved through molecular-scale bond energy dissipation, to orchestrate the crystallization process and manage mechanical stress. Consequently, we achieve a near two-fold enhancement in carrier diffusion length, surpassing 8 µm within the polycrystalline film. The resulting [HA-AA][EMIES]-based devices demonstrate superior efficiencies of 26.45% for rigid substrates and 25.14% for flexible devices, while exhibiting exceptional resilience against both ambient air exposure and mechanical bending. This work establishes a direct route to eliminate deleterious defects and residual strain in perovskites, offering a promising pathway to accelerate the development and commercial deployment of large-area, stable perovskite photovoltaics.