Realizing Efficient Broadband Near-Infrared Emission under Blue Light Excitation in Sb3+-Doped Zero-Dimensional Organic Tin(IV)-Based Metal Halides via Coordination Structure Modulation

Realizing Sb3+-activated efficient broadband near-infrared (NIR) emission under blue light excitation remains a significant challenge in lead-free metal halides. To overcome the above difficulties, a coordination structure modulation strategy was adopted, and the broadband NIR emission under blue light excitation was achieved in Sb3+-doped zero-dimensional (0D) organic tin(IV) bromide. Compared to the weak visible light emission with a photoluminescence quantum yield (PLQY) of 2.4% for pure (TBP)2SbBr5 (TBP = Tetrabutylphosphonium), Sb3+-doped (TBP)2SnBr6 exhibits efficient broadband NIR emission band at 705 nm with PLQY of 33.2% upon 452 nm excitation, which stems from self-trapped exciton emission. Combined with experiments and theoretical calculations, we find that the large excited-state lattice distortion degree compared to the ground state and the narrow bandgap are dominant reasons for Sb3+-doped (TBP)2SnBr6 shows efficient NIR emission under blue light excitation. More particularly, Sb3+-doped (TBP)2SnBr6 also has excellent anti-water stability, existing stably in water for more than 4 hours while maintaining high luminous efficiency. Based on the excellent stability and unique optical properties of Sb3+-doped (TBP)2SnBr6, a high-performance NIR light-emitting diode (LED) was fabricated by combining a commercial blue LED chip, and its application in night vision was demonstrated.