Electroluminescence properties of three-layered organic light-emitting diodes with a layer of tetraphenylchlorin or tetraphenylporphine

We constructed two organic electroluminescence (EL) devices that had a ligh t-emitting layer of tetraphenylchlorin (TPC) or tetraphenylporphine (TPP), which was inserted between a hole transport layer of N,N'-diphenyl-N,N'-bis (3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine (TPD) and an electron transpo rt layer of tris(8-hydroxyquinoline) aluminum (Alq(3)). The TPC device emit ted a far-red EL band at around 750 nm? which we ascribed to emission from aggregated TPC sites, The TPP device emitted a red EL band at 660 nm and a far-red EL band at 720 nm? which we ascribed to emission from monomer-like TPP sites. Both devices also emitted green EL bands due to Alq(3) emission although the emission was partly filtered off by absorption of the TPC or T PP layer.