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A novel blue light emitting polymer was designed and synthesized via alternative conjugated 9,9-dioctylfluorene and 9-(6-(9H-carbazol-9-yl)hexyl)-9H-carbazole, named PF2Cz. It exhibited high thermal stability, good film morphology and strong deep-blue emission peaks at 408 and 429 nm in film. The triplet energy level of PF2Cz (ET = 2.30 eV) was also improved. Non-doped and doped devices were both prepared by solution process to characterize the electroluminescent (EL) properties of PF2Cz. In non-doped devices, PF2Cz acted as blue emitter which exhibited a Commission Internation de L'Eclairage (CIE) coordinate of (0.164, 0.102) and a external quantum efficiency (EQE) values of 1.28%. Moreover, the doped phosphorescent devices utilized PF2Cz as host material obtained a closed-white light emission with a content of 1 wt% dopant. All these results indicated that the fluorene-carbazole derivatives could be a promising molecular design strategy for the synthesis of blue light and host organic semiconductors.

The blue-light-emitting Ir(III) complexes using 2-(3-(trifluoromethyl) -1H-1,2,4-triazol-5-yl)pyridine and fluorinated 2-phenylpyridine as ligands were synthesized and characterized in details. Their molecular structures were confirmed by 1H NMR, FT-IR and elemental analyzer. The emission peaks of complex (F2,4ppy)2Ir(tfmptz) using 2-(2,4-difluorophenyl)pyridine as main ligand are located at 457 and 481 nm. Increasing the number of F atoms leads to a lower the lowest unoccupied molecular orbital energy level. Phosphorescent organic light-emitting devices doped the synthesized Ir(III) complexes into 4,4′-N,N′-dicarbazolebiphenyl as emitting layers were fabricated. The based-(F3,4,5ppy)2Ir(tfmptz) device shows the maximum current efficiency of 9.9 cd/A with the electroluminescent peaks at 471 and 502 nm.

A novel host material, namely 9-(6-(3-phenyl-5-(pyridin-2-yl)-4 H -1,2,4-triazol-4-yl)hexyl)-9 H -carbazole (PPHCZ) was designed and synthesized by incorporating 1, 2, 4-triazol as the electron-withdrawing moiety and carbazole as electron-donating moiety using hexyl as bridge. The photophysical, electrochemical, thermal properties and performances in phosphorescent organic light-emitting devices (PhOLED) were thoroughly characterized. PPHCZ with a high triplet energy level (3.01 eV) exhibited an obvious intermolecular interaction in thin film. Green and blue PhOLEDs using fac -tris(2-phenylpyridine)iridium and iridium(III) bis(4,6-difluorophenyl)-pyridinato N,C 2 ′]picolinate as phosphorescent dopants have been fabricated.