Carbazole dendrimers up to 4th generation were synthesized. They showed significantly high T(g), amorphous and stable electrochemical properties, and great potential as solution processed hole-transporting materials for OLEDs. Alq3-based green devices exhibited high luminance efficiency and CIE coordinates of 4.45 cd A(-1) and (0.29, 0.53), respectively.

No abstract

No abstract

New bifunctional materials namely BTTF, TPTF and BPTF having 9,9-bis(4-diphenylaminophenyl) fluorene as a molecular platform were synthesized and characterized. These molecules showed strong blue emission in both solution and solid state with a solution fluorescence quantum efficiency of up to 74% and were thermally stable amorphous materials with glass transition temperature well above 170 C. The abilities of these materials as blue light-emitting materials for blue OLEDs and holetransporting materials for green OLEDs in terms of device performance and thermal property were superior to a commonly used N,N 0 -diphenyl-N,N 0 -bis(1-naphthyl)-(1,1 0 -biphenyl)-4,4 0 -diamine (NPB). Efficient non-doped blue and Alq3-based green OLEDs with maximum luminance efficiencies and CIE coordinates of 2.06 cd A À1 and (0.15, 0.13), and 4.94 cd A À1 and (0.29, 0.52) were achieved, respectively, with BPTF having two pyrene substituents as the emitting layer and the hole-transporting layer, respectively.

A series of novel D-π-A type organic dyes, namely, GnTA (n = 1-4), containing carbazole dendrons up to fourth generation as a donor, bithiophene as π-linkage, and cyanoacrylic acid as acceptor were synthesized and characterized for applications in dye-sensitized solar cells (DSSCs). The photophysical, thermal, electrochemical, and photovoltaic properties of the new dyes as dye sensitizers were investigated, and the effects of the carbazole dendritic donors on these properties were evaluated. Results demonstrated that increasing the size or generation of the carbazole dendritic donor of the dye molecules enhances their total light absorption abilities and unluckily reduces the amount of dye uptake per unit TiO2 area because of their high molecular volumes. The latter was found to have a strong effect on the power conversion efficiency of DSSCs. Importantly, electrochemical impedance spectroscopy (EIS) revealed that the size or generation of the donor had a significant influence on a charge-transfer resistance for electron recombination at the TiO2/electrolyte interface, causing a difference in open circuit voltage (Voc) of the solar cells. Among them, dye G1TA containing first generation dendron as a donor (having lowest molecular volume) exhibited the highest power conversion efficiency of 5.16% (Jsc = 9.89 mA cm(-2), Voc = 0.72 V, ff = 0.73) under simulated AM 1.5 irradiation (100 mW cm(-2)).