Spiro linked compounds for use as active materials in organic light emitting diodes

Spiro-linkage of low molecular weight entities as a new structural concept for the design of new active materials for electroluminescent applications is presented. These spiro linked compounds result in nonpolymeric organic glasses with high thermal stability as can be derived from their high glass transition temperatures (T-g), and characterized by differential scanning calorimetry. Blue emitters based on spiro linked oligophenyles are presented. These compounds are soluble in common organic solvents and show high photoluminescence quantum efficiency in the solid state and high morphologic stability with glass transition temperatures up to 250 degrees C. Charge transport materials based on spiro linked versions of 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD) for electron transport, and spiro linked versions of triphenyldiamin derivatives (TPD) for hole transport show improved morphologic properties with nearly unchanged electronic properties compared to the parent compounds. High quality amorphous films can be prepared with the spiro compounds by vapor deposition as well as by simple spin coating.