Tetravalent tin complex with high electron affinity for electroluminescent applications

We report the synthesis and electroluminescent properties of the organometallic complex diphenyltin bis-hydroxyquinoline (Sph₂q₂). The complex was prepared by the reaction of diphenyltin dichloride with 8-hydroxyquinoline and shows an absorption cutoff wavelength of 460 nm and bright photoluminescence with a peak wavelength at 508 nm. The ionization potential of Sph₂q₂ was determined to be ∼6.0 eV by photoemission apparatus, and the electron affinity is estimated to be 3.3 eV. Sph₂q₂ was used as an emitting and electron injection layer in bilayer devices. The electroluminescence (EL) properties and charge injection properties of Sph₂q₂ are characterized. Sph₂q₂ is easily soluble in common organic solvents and further modification of its properties is possible. The results indicate that tetravalent tin complexes are potential emitting and charge injection materials for EL applications.