Efficient near‐infrared light‐emitting diodes via enlarging grains of tin‐based perovskites

Tin (Sn) perovskites light‐emitting diodes (PeLEDs) have achieved significant attention because of their enormous potential to replace their hazardous lead counterparts. However, the fast crystalline process leads to growth of small‐grain Sn‐based perovskite films with high‐density grain boundaries that induce Sn 2+ oxidation and severe non‐radiative recombination. In this work, we propose a large‐grain strategy to fabricate Sn‐based perovskite films, wherein penicillamine molecules are introduced to enhance coordination with Sn 2+ and I − ions. The strong binding between penicillamine and perovskite significantly slows down the crystallization process, leading to a high‐quality film with enlarged grains for efficient near‐infrared (NIR) emission. Moreover, penicillamine helps suppress partial Sn 2+ oxidation by reducing Sn 4+ formation and passivating defect sites, specifically Sn 2+ vacancies. Owing to these synergistic enhancements, effective NIR Sn‐based PeLEDs are obtained, reaching a maximum external quantum efficiency (EQE) of 17.5% at 894 nm and an operational half‐lifetime of 0.95 h under current densities of 100 mA cm −2 . This work presents a potential method to control the coordination ability with Sn 2+ and I − ions and further tune the crystallization process of Sn‐based perovskites for highly efficient PeLEDs.