Effect of methyl substituents on the N-diaryl rings of anthracene-9,10-diamine derivatives for OLEDs applications

A series of N-diaryl-anthracene-9,10-diamine derivatives with methyl substituents at meta or para position of N-diaryl rings were synthesized and used as dopants for Organic Light-Emitting Devices (OLED). The effects of substituted methyl substituents have been compared based on both materials and solid device evaluation. The performance of solid state devices in the configuration of ITO/N,N′-bis(naphthalene-1-yl)-N,N′-bis(phenyl)benzidine (NPB) (40 nm)/3% dopant: 9,10-di(2-naphthyl)anthracene (AND) (40 nm)/tris(8-hydroxyquinoline)aluminum (Alq3) (20 nm)/LiF (1.5 nm)/Al (200 nm) have been studied. As compared to the non-substituted dopant N,N,N′,N′-tetraphenyl-anthracene-9,10-diamine, current efficiency was promoted to approximately 2.9, 6.33, and 7.94 cd/A, and power efficiency was improved by 0.74, 2.26 and 3.02 lm/W, for dopants with the substituted methyl groups at meta, para and both meta/para positions, respectively. The device, prepared by using the dimethyl-substituted dopant at meta/para position, showed the best performance when the luminance of the device reached 24,991 cd/m2 with CIE (x, y) = (0.38, 0.59), and the efficiency of the device reached 24.99 cd/A and 7.48 lm/W at a driving current of 100 mA/cm2. As compared with a device made of a coumarin (C545T)/Alq3-based emitting layer, the dimethyl-substituted dopant/ADN-based device developed in this study, exhibited great improvement in device performance.

The first reported case in which the N-diaryl amino anthracenes (compound TAD, TmAD, TpAD and TmpAD) were used as good dopants in the wide band gap ADN host system for OLEDs farication.Figure optionsDownload as PowerPoint slideResearch highlights
► Guest/host were both based on anthracence derivatives.
► N-diaryl amino anthracenes were used as dopants in the wide band gap ADN host.
► The effects of substituted methyl groups of dopants have been compared.
► High EQE of 8.2% is achieved in the TmpAD -based devices.
► Excellent performances better than coumarins/Alq3 based devices.