Efficient solution-processed light-emitting diodes based on organic-inorganic hybrid antimony halides

Organic-inorganic hybrid antimony halides are emerging emitters for solution-processed light-emitting diodes. However, achieving high-efficiency electroluminescence remains challenging resulting from the non-radiative recombination within emitters and inferior charge transport within device. Here, we develop an organic cation engineering to design a carbazole-functionalized triphenyl(9-ethyl-9H-carbazol-3-yl) phosphonium (TPPEtCz⁺), which enables a (TPPEtCz)₂Sb₂Br₈ film with good luminescence and achieves an improved charge transport within device. The TPPEtCz⁺ facilitates strong hydrogen bonding with the [Sb₂Br₈]^2- species and dichloromethane solvent, resulting in a more complete crystal restructuring, thus improving the quality of films. Moreover, non-covalent π-π interactions between carbazole moieties of (TPPEtCz)₂Sb₂Br₈ and benzimidazole moieties of electron-transport TPBi modify the interfacial contact that promotes electron transport and injection. Consequently, our light-emitting diodes reach a peak external quantum efficiency of 19.4% and half-lifetime of 10,190 min at 100 cd m^-2. These discoveries provide critical insights into the cation design of hybrid devices that are promising for practical applications.