Synthesis, characterization, and electroluminescence properties of a donor–acceptor type molecule for highly efficient non-doped green organic light-emitting diodes

We synthesized a new donor–acceptor type (D–A type) green fluorescent emitter, 3,7-bis(1-(biphenyl-4-yl)-1H-benzo[d]imidazole-2-yl)-10-phenyl-10H-phenothiazine (PhBBPP), which consists of phenylphenothiazine as an electron donor and biphenylbenzimidazole as an acceptor. Its thermal and photophysical properties, and energy band structure were studied, and also organic light-emitting diodes (OLEDs) with various device structures were fabricated using PhBBPP as an emitting layer. The optimized OLED device with a structure of [ITO/NPB (40 nm)/PhBBPP (30 nm)/TPBi (30 nm)/Alq3 (10 nm)/LiF (1 nm)/Al (100 nm)] showed a turn-on voltage of 3.4 V, a luminous efficiency of 12.1 cd/A, and an external quantum efficiency of 4.0% at 100 cd/m2 with a maximum luminance of 8200 cd/m2.