Tailor‐Made Host–Guest Organic–Inorganic Hybrid Antimony Halide Enables Efficient Light‐Emitting Diodes

Organic-inorganic antimony (Sb) halides are garnering increasing interest for lead-free perovskite light-emitting diodes (LEDs), but the non-radiative recombination and poor charge transport are hard-treat case to restrict their electroluminescent performance. Here we developed efficient Sb halide LEDs based on the tailor-made host-guest (Ph₄P)₂SbCl₅ (Ph₄P = tetraphenylphosphonium) emitters that enable good luminescence and charge transport properties simultaneously. Experimental and theoretical studies reveal that the self-trapped excitons triggered by excited-state structural deformation were localized in spatial-confined [SbCl₅]^2- polyhedrons, generating a high photoluminescence quantum yield (96.8%). The host-guest (Ph₄P)₂SbCl₅ emitter with 35DCzPPy (3,5-bis(3-(carbazol-9-yl)phenyl) pyridine) host shows an enhanced radiative recombination, rooting in the type-I energy level configuration and efficient energy transfer between 35DCzPPy and (Ph₄P)₂SbCl₅. The 35DCzPPy with delocalized molecular orbital enhances the electrical properties of emitters, which balances the charge transport/injection in devices. These benefits result in efficient Sb halide LEDs with a record-high luminance of 6689 cd m^-2 and external quantum efficiency of 6.47%. Moreover, large-area LEDs with an emitting area up to 900 mm² were demonstrated with uniform emission. This work provides meaningful insights into reaching high-performance metal halide LEDs towards future practical applications.