Embedding Te⁴⁺ into Sn⁴⁺-Based Metal Halide To Passivate Structure Defects for High-Performance Light-Emitting...

Low-dimensional lead-halide hybrids are an emerging class of optical functional material but suffer the problems of toxicity and poor air stability. Among lead-free metal halides, tin(IV)-based metal halides are promising optoelectronic materials due to their robust structure and environmental friendliness. However, their photoluminescence (PL) properties are poor, and the underlying mechanisms are still elusive. Herein, a stable Sn⁴⁺-based halide hybrid, (C₄H₇N₂)₂SnCl₆, was developed, which however exhibits poor PL properties at room temperature (RT) due to the lattice defects and the robust crystal structure. To enhance its PL efficiency, the Te⁴⁺ ion with a stereoactive 5s² lone pair has been introduced into the lattice. As a result, Te⁴⁺-doped (C₄H₇N₂)₂SnCl₆ displays broadband orange emission (∼640 nm) with a PL efficiency of ∼46% at RT. Interestingly, Te⁴⁺-doped (C₄H₇N₂)₂SnCl₆ shows triple emission bands at 80 K, which could be due to the synergistic effect of the organic cations and the self-trapped state induced by Te⁴⁺. Additionally, high-performance white light-emitting diodes were prepared using Te⁴⁺-doped (C₄H₇N₂)₂SnCl₆, revealing the potential of this material for lighting applications. This study provides new insight into the PL mechanism of Sn⁴⁺-based metal-halide hybrids and thus facilitates the design and development of eco-friendly light-emitting metal halides.