Inverted transparent multi-layered vacuum deposited organic light-emitting diodes with electrically doped carrier transport layers and coumarin doped emissive layer

摘要

Inverted transparent multi-layered vacuum deposited organic light-emitting diodes (OLEDs) employing an indium-tin-oxide (ITO) coated glass substrate directly as cathode and a semitransparent top Au thin film as anode comprise an emissive layer sandwiched in between n- and p-doped charge transport layer with appropriate blocking layers to form a nip structure. By doping the 8-tris-hydroxyquinoline-aluminum (Alq_3) layer with highly fluorescent molecules, coumarin 6, the external current efficiency has been improved by about a factor of 2, up to 6 cd/A, in comparison with intrinsic Alq_3 devices. The devices are about 50 percent transparent and emit green light from both sides (4.4 V for 100 cd/m~2).