Immiscible polymers in double spin-coated electroluminescent devices containing phenyl-substituted tris(8-hydroxyquinoline)aluminum derivatives soluble in a host polymer

Three new phenyl-substituted tris(8-hydroxyquinoline)aluminum (AlQ₃) derivatives have been synthesized: tris(5-phenyl-8-quinolinolate-N1,O8)aluminum, tris(5,7-diphenyl-8-quinolinolate-N1,O8)aluminum, and tris[5,7-bis(p-fluorophenyl)-8-quinolinolate-N1,O8]aluminum. These AlQ₃ derivatives are easily soluble in common organic solvents and form solid-phase solutions in a poly(aryl ether ketone) host polymer (A435). These interesting properties allow the use of soluble AlQ₃ derivatives in double spin-coated organic light-emitting devices of the type ITO/NPB-QP/A435 + 50 wt% soluble AlQ₃ derivative/Mg, where NPB-QP is a hole-transporting polymer insoluble in toluene, the solvent for A435. Typical double spin-coated organic layer devices are characterized by an emission at 530-539 nm, a threshold voltage of 6-9 V, and a maximum luminance of 1800-4000 cd/m² at 21-25 V.