New deep blue emitting materials 2,8-bis(3,5-diphenylphenyl)-6,6,12,12-tetraethyl-6,12-dihydrodiindeno[1,2-b:1',2'-e]pyrazine (DPP-EPY) and 2,8-bis(3',5'-diphenylbiphenyl-4-yl)-6,6,12,12-tetraethyl-6,12-dihydrodiindeno[1,2-b:1',2'-e]pyrazine (DPBP-EPY) were synthesized through introduction of m-terphenyl or triphenylbenzene bulky side groups in a new indenopyrazine core. These materials all showed high thermal stability and highly reduced intermolecular interaction. DPP-EPY and DPBP-EPY showed PL maxima of 456 nm and 460 nm in deep blue region and narrow PL spectra with full-width at half-maximum (FWHM) of 46 nm and 52 nm, respectively. As a result of making non-doped OLED devices using these synthesized materials as emitting layers, DPP-EPY showed EL spectrum of 452 nm, very narrow FWHM of 46 nm, luminance efficiency of 1.04 cd/A with current density of 10 mA/cm2 and CIE coordinate of (0.161, 0.104), creating a deep blue OLED close to the National Television System Committee (NTSC) blue standard.

A novel core material, indenopyrazine, has been substituted with ethyl, phenyl, tolyl or fluorenyl groups on the locations 6 and 12, to newly synthesize four blue-emitting materials for OLED. Their electro-optical properties were compared through UV-Vis absorption, PL spectra and cyclic voltammetry, according to substituents of the core system of indenopyrazine. Non-doped OLED devices were fabricated by using the synthesized materials as emitting material layers, and among them, SF-EPY showed a highly-efficient luminescence with EL spectrum of 458 nm, luminous efficiency of 2.62 cd/A and CIE coordinates of (0.152, 0.142) at a current density of 10 mA/cm 2 .