Organic light-emitting device with a mixed ligand 8-quinolinolato aluminium chelate as emitting and electron transporting material

Double layer (DL) electroluminescent devices, made with TPD (75%) in polycarbonate (PC) and with a mixed ligand 8-quinolinolato aluminium chelate as electron transporting and emitting material, show higher electroluminescence (EL) quantum yield (2.2%) and an increased blue EL emission in comparison with Tris-(8-hydroxyquinolinate)Al(III) (Alq(3)). The solid state photoluminescence (PL) quantum yield is as high as 60%, about five-fold the Alq3 value. In spite of the high PL yield, EL efficiency is not as much high; this can be attributed to a strong electron mobility dependence on the electric field, which contributes to a slower increase with the field of the EL quantum yield. (C) 2001 Elsevier Science B.V. All rights reserved.