Dynamic Reconfiguration of Hydrogen-Bonded Networks to Modulate Perovskite Crystallization

Abstract

Precise control of perovskite crystallization remains challenging because hydrogen bonds (H-bonds), which govern precursor interactions and nucleation pathways, are often treated as static rather than dynamic entities. Here, we propose a novel dynamic H-bond network strategy to regulate perovskite crystallization via the steric modulation of the H-bond donor in a deep eutectic solvent (DES). Replacing urea with N-methylurea (NMU) reconfigures the H-bond network of NMU-DES, which increases the number of moderately coordinating sites and promotes self-association with long H-bond lifetimes, thereby prolonging the halide···H interactions between NMU-DES and PbI2，yielding a stable precursor reservoir. Urea-based DES generates flexible and transient interactions that retard perovskite nucleation, whereas NMU-DES induces stronger, spatially localized interactions that self-assemble into an interfacial H-bond network, thereby regulating perovskite nucleation and crystal growth and yielding films with reduced defect densities. As a result, NMU-DES–based devices achieve a power conversion efficiency of 26.33% and outstanding operational stability, retaining >94% of their initial efficiency after 1,570 h of continuous illumination. This dynamic-network strategy transcends static passivation, offering rational control of weak forces as a generalizable pathway toward highly efficient and stable perovskite and other solution-processed optoelectronic materials.