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 light-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 transport layer of tris(8-hydroxyquinoline) aluminum (Alq3). The TPC device emitted 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 Alq3 emission although the emission was partly filtered off by absorption of the TPC or TPP layer.