A series of organic sensitizers with the direct electron injection mechanism and a high molar extinction coefficient comprising double donors, a π-spacer, and anchoring acceptor groups (D−D−π−A type) were synthesized and characterized by experimental and theoretical methods for dye-sensitized solar cells. (E)-2-Cyano-3-(5″-(4-((4-(3,6-di-tert-butylcarbazol-9-yl)phenyl)dodecylamino)phenyl)-[2,2′:5′,2″-terthiophene]-5-yl)acrylic acid showed performance with a maximal incident photon to electron conversion efficiency of 83%, J sc value of 10.89 mA cm −2 , V oc value of 0.70 V, and fill factor of 0.67, which correspond to an overall conversion efficiency of 5.12% under AM 1.5G illumination. The molecular geometry, electronic structure, and excited states were investigated with density functional theory, time-dependent density functional theory, and the symmetry-adapted cluster-configuration interaction method. The double donor moieties not only contribute to enhancement of the electron-donating ability, but also inhibit aggregation between dye molecules and prevent iodide/triiodide in the electrolyte from recombining with injected electrons in TiO 2 . Detailed assignments of the UV−vis spectra below the ionization threshold are given. The low-lying light-harvesting state has intramolecular charge transfer character with a high molar extinction coefficient because of the long π-spacer. Our experimental and theoretical findings support the potential of direct electron injection from the dye to TiO 2 in one step with electronic excitation for the present D− D−π−A sensitizers. The direct electron injection, inhibited aggregation, and high molar extinction coefficient may be the origin of the observed high efficiency. This type of D−D−π−A structure with direct electron injection would simplify the strategy for designing organic sensitizers.

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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.

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