New Pyrene Derivatives Having Rigid Imidazole Moiety for Blue Emitters.

Pyrene, imidazole and dibenzofuran were used to synthesize new blue emitters of 1-(4-(dibenzo[b,d]furan-4-yl)phenyl)-2-(pyren-1-yl)-1H-phenanthro[9,10-d]imidazole (BFP-PI) and 1-(4-(dibenzo[b,d]furan-4-yl)phenyl)-4,5-diphenyl-2-(pyren-1-yl)-1H-imidazole (BFP-DPI). In the film state, BFP-PI and BFP-DPI show photoluminescence (PL) maximum values of 462 nm and 459 nm. The relative PL quantum efficiency (PLQY) of BFP-PI and BFP-DPI is 89.16% and 79.2% by using reference compound of 9,10-diphenylanthracene. The device using BFP-PI in the non-doped state as emitting material showed current efficiency (C.E.) of 3 cd/A and external quantum efficiency (E.Q.E.) of 2.15%, and the device using BFP-DPI as emitting material exhibited C.E. of 2.64 cd/A and E.Q.E. of 1.6%.

Synthesis and Electroluminescence Property of Pyrene Derivatives Including Dibenzothiophene and Imidazole Moiety.

Pyrene, imidazole and dibenzothiophene were used to synthesize new blue emitters of 1-(4-Dibenzothiophen-2-yl-phenyl)-4,5-diphenyl-2-pyren-1-yl-1H-imidazole (DDPI) and 1-(3-Dibenzothiophen-4-yl-phenyl)-2-pyren-1-yl-1H-phenanthro[9,10-d]imidazole (DPPI). The optical properties of synthesized compounds were measured by UV-visible absorption and PL spectra. In the vacuum deposited film state, the PL maximum value is 463 nm for DDPI and 455, 471 nm for DPPI. The device using DDPI as emitting material showed CE of 2.38 cd/A, PE of 1.38 lm/W, and EQE of 1.54%, device using DPPI as emitting material exhibited CE of 3.65 cd/A, PE of 2.31 lm/W, and EQE of 3.07%. Also, OLED devices of DDPI and DPPI devices exhibited CIE coordinate of (0.20, 0.23) and (0.16, 0.16).

Hybrid White Organic Light Emitting Diodes Using Dual Core Blue Fluorescent Emitter.

White OLED (WOLED) devices were fabricated using blue emitting materials, TP-AA-TP, TP-AA-TPB, and TPB-AA-TPB, and yellow emitting material polyphenylenevinylene derivative (PDY 132). Three devices were fabricated with the following structure: ITO/PEDOT:PSS (50 nm)/PDY-132 (40 nm)/NPB (10 nm)/Blue EML (30 nm)/Alq3 (20 nm)/LiF (1 nm)/Al (200 nm). PDY-132 was used by spin coating, and then three blue fluorescent materials were used by vapor deposition to form a white light emitting device. The color coordinates of WOLED using TP-AA-TP, TP-AA-TPB and TPB-AA-TPB were (0.291, 0.317), (0.317, 0.371) and (0.345, 0.457), respectively. Device using TP-AA-TP as blue emitting material showed the highest efficiencies at 10 mA/cm², L.E of 5.58 cd/A, P.E of 2.16 lm/W and E.Q.E of 2.96%.