Simultaneous Regulation of Crystallization and Suppression of Oxidation in CsSnI₃ Perovskite Enables Efficient and Stable Near-Infrared Light-Emitting Diodes

Tin-based halide perovskite light-emitting diodes (PeLEDs) emitting in the near-infrared region beyond 900 nm hold tremendous potential for applications in night vision, biomedicine, and communications. However, rapid crystallization and oxidation of Sn²⁺ in tin-based perovskites pose significant challenges for achieving stable PeLEDs with high performance. Here, we report an efficient all-inorganic CsSnI₃-based PeLED by employing a multifunctional hesperetin additive to modulate the crystallization kinetics and inhibit the oxidation process of the perovskite films. Hesperetin possesses hydroxyl groups alongside oxygen atoms offering lone electron pairs, which form hydrogen bonds with I^- and strongly coordinate with Sn²⁺, respectively, slowing down crystallization of CsSnI₃ and resulting in high coverage density films. Importantly, the coordination of hesperetin with Sn²⁺ protects the perovskite films from Sn²⁺-to-Sn⁴⁺ oxidation. Finally, we demonstrate efficient and stable PeLEDs with a peak at 948 nm, an external quantum efficiency of 4.7%, and a half-lifetime of over 11 h.